Getting Technical with your Tech II

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Getting Technical with your

Tech II

Video Presented by:

Bob Augustine of

Vetronix

Manual Written by:

Mike Herbert of

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Disclaimer of Warranties:

Although the test procedures and the test information in this manual were obtained by an ASE Certified Master Technician with known good test equipment on real Domestic and Import vehicles, individual tests may vary due to equipment and technicians. No warranty can be made to personal testing procedures for accuracy or completeness obtained from the ideas of this manual, nor does its author or anyone connected with him assume any responsibilities or liabilities. The use of this manual is conditional on the acceptance of this disclaimer. If the terms of this disclaimer are not acceptable, please return this manual immediately.

Mike Herbert

ASE Master Certified Technician Automotive Diagnostic Solutions 937-498-4384

[email protected]

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We will start off by discussing some of the terminology we will be referring to in the video.

Protocol: This refers to the type of communication bus that the computers use to communicate with each other or your scanner.

Key Data Bus Terms

UART: Universal Asynchronous Receive and Transit.

• This is the communication protocol that General Motors has been using since the late 80’s.

• The system operates at 5 volts.

• The baud rate that the data transmits is 8192 bits per sec.

E & C: Entertainment and Comfort • This system operates at 12 volts.

• The baud rate that the data transmits is also 8192 bits per sec. • Typically this section is for the entertainment and climate controls.

Key Word 2000:

• This protocol was mandated by the government for OBDII. • It requires special software in the scanner.

• Very few vehicles use this protocol. One example is the Cadillac Catera.

• This system operates at 12 volts.

• The baud rate that the data transmits is 10,400 bits per sec.

SBI: Simple Bus Interface

• Typically used on 98 and newer GM vehicles.

• Generally used for door modules, since they do not need to communicate as quickly as other modules.

• The baud rate for this system has not been released by GM, but keep in mind that it is a much slower rate than the other modules.

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SPI: Serial Peripheral Interface

• Typically used on a vehicle that has a “Heads up Display”. • This system operates at 12 volts.

• There is no published baud rate on this vehicle.

Class 2:

• This is where the majority of the video is going to be focused. • This is GM’s newer protocol that they are using.

• The baud rate that the data transmits is 10,400.

• Class 2 operates under a variable pulse width, unlike the other protocols, that operated under a fixed pulse width.

• The programming can determine priority over communications between the modules. For example, the air bag communication has priority over the door module communications.

Class C:

• The baud rate that the data transmits is 8192 bits per sec.

• An example of a Class C system would be an electronic throttle control vehicle.

CAN: Controller Area Network

• This is the new protocol that is being mandated by the EPA. • It is slowly being phased in and will be required by 2007. • In 2003 the Saturn Ion and Saab is CAN compliant. • There are three different CAN protocols.

• CAN C operates at 2.5 ± 1 volt…has a baud rate of 500k.

• CAN B operates at 2.5 ± 1 volt…has a baud rate of 250k and may go as low as 83,300.

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UART Bus Configuration

This configuration was used primarily in pre-1997 model vehicles. Typically this was used in the Cadillac, Corvette and some C and H bodies, such as the Park Ave and Bonneville.

Notice that the modules are set up in a ring configuration and they are all connected by a two wire pair. The reasoning behind the two wire

configuration is if there was a loss of communication on one wire you would have a back-up. If you were ever to remove the cover on the back of an ALDL connector on a 93 – 94 Bonneville or Park Ave, you would notice a shorting bar across terminals L and M. You could unplug the shorting bar to determine if you had a communication problem on one side of the bus

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OBD II Trouble Code

P 0 3 0 4

Above we are viewing a typical OBD II trouble code. Also listed are the definitions for each letter or digit. The main focus of this video will be the “U” codes. The “U” represents a network code.

Although this may be a review for most of you, we will briefly discuss OBD II code descriptions. The first digit indicates if the code is for the Powertrain, Chassis, Body or the Network. The next digit indicates whether the code is generic or OEM specific. The third digit represents the specific system that is failing. The last two indicate the particular circuit in that system that is failing. 1- Fuel Trim 2- Fuel Trim (Injector) 3- Misfire 4- Aux Emission 5- Idle Circuits 6- Computer Output 7/8- Transmission P-Powertrain C-Chassis B-Body U-Network 0- Generic 1- OE Specific Code #

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U1096

U = Network

1 = Manufacturer Specific

The last three digits are different than we are accustomed to. They do not represent a specific component in the circuit, but rather a specific control module on the bus circuit that is having a problem. By looking at the code listed above and viewing our chart, we can see that the problem circuit is the IPC module. The IPC indicates it is an instrument panel code.

016: PCM = Powertrain Control Module

088: SDM = Sensing Diagnostic Module or Air Bag Module 041: EBCM = Electronic Brake Control Module

128: Radio or Entertainment System Control Module 176: RFA = Remote Function Module

064: BCM = Body Control Module 040: TCS = Traction Control Module

096: IPC = Instrument Panel Control Module

153: HVAC = Heating, Ventilation and Air Conditioning Control Module

PCM---016

BCM---064

SDM---088

TCS---040

EBCM---041

IPC---096

Radio---128

HVAC---153

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Buddy System

Class 2 systems have what could be referred to as a “Buddy System”. This means a module is responsible for monitoring different modules. Every two and one half seconds the module sends out a “State of Health” message. This will indicate to the other modules that it has a power and ground and it can communicate with the other modules. If the module fails to send a “State of Health” message two consecutive times, or within five seconds, the “Buddy Module” will set a code for that module. Keep in mind that the module that is failing is not the module you will be receiving the trouble code from. You are actually retrieving it from the “Buddy Module”. This is why it is

important to have a scanner that will allow you to have access to all the modules.

Some of the more important modules, such as the Air Bag or ABS module, will have more than one “Buddy Module” assigned to monitor them. If this is the case you will notice a code in multiple modules when one fails.

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OBD II Diagnostic Connector

The above image is of a standard OBD II diagnostic connector that is under the dash of all 1996 and newer vehicles. There are certain pins that all manufacturers had to leave open to meet the OBD II guidelines. The highlighted pins above are special to General Motors.

Pin 2: This is for Class 2 Enhanced Data

Pin 4: Mandated by the EPA for chassis ground Pin 5: Mandated by the EPA for signal ground Pin 6: CAN low signal

Pin 9: Primary UART Pin 14: CAN high signal Pin 16: Battery power

Pin 9- Primary

UART Pin 14- CAN

High E & C Pin 16- Battery Power Pin 2- GM Class 2 Enhanced Data or J1850 Bus + L Line Pin4- Chassis Ground Pin 5- Signal Ground

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OBD II Diagnostics

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Ring Configuration

This image above is referred to as a “Ring Configuration”. The data rides on the bus to pin 2 in the DLC connector. This system is more difficult to

diagnose because of the way the wiring is set up. You will need to have access to the proper schematic and have a good understanding of the circuit. You will have to follow the wiring diagram to identify where the open circuit in the wiring is, if there is a problem in the bus circuit.

General Motors seems to be phasing this design out in favor of the star design. CD Changer Vehicle Interface Module Rear Integration Module Remote Function Module Memory Seat Module Electronic Brake Control Module Powertrain Control Module LH Door Control Module Radio Instrument Cluster HVAC Dash Integration Module Sensing Diagnostic Module Heads Up Display Vehicle

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Star Configuration

The “Star Configuration” is the latest set-up that General Motors is using. The “Star Configuration” incorporates all the data lines into one central location. This will make diagnosis much easier.

The example we will be using is the Cadillac Escalade. We will be looking at one of the three “Star Connectors” that this vehicle has on board. When we are looking at the “Star Connector” and compare it to the wiring

diagram, you will see how much easier it is to diagnose a data bus problem on the “Star Configuration” compared to the “Ring Configuration”. Once you find the “Star Connector” for the circuit you are diagnosing, you will see how easy it is to go from module to module for diagnosis. Since you can not perform these tests without a scan tool, you will find out how important it is to have the proper scan tool for diagnosing these systems.

Remote Door Lock Module HVAC Splice Pack 1 Electronic Suspension Control Module Powertrain Control Module Electronic Brake/Trac Control Module Sensing Diagnostic Module Instrument Cluster CD Changer Radio LH Door Control Module LH Seat Control Module RH Door Control Module Splice Pack 2

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Star Configuration Corvette

Some vehicles will have a UART and a Class 2 Bus—as in the example above. This vehicle is a 1999 or 2000 corvette. It has a Class 2 data bus that is accessed at P.I.N. 2 on the Diagnostic Link Connector (DLC). By viewing the example above, we can then see that the Class 2 bus is broken into two sections: “Splice Pack 1” and “Splice Pack 2”. The number of “Splice Packs” on a vehicle will vary, depending on the amount of control modules. You will notice on “Splice Pack 1” there are five separate modules

connected: The Remote Door Lock Module, the Heating, Ventilation and Air Conditioning Module (HVAC), the Electronic Brake/Traction Control Module, the Powertrain Control Module, and the Electronic Suspension Control Module. Then “Splice Pack 2” consists of the Left Hand Door Control Module, the Left Hand Seat Control Module, and the Right Hand Door Control Module.

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The Instrument Cluster, Radio and CD changer are on P.I.N. 14…which is an E & C bus…which is a different protocol. If you plug in your Tech II scanner and go into Class 2 Diagnostics, you will not see IPC, Radio or CD Changer listed. Also the Sensing Diagnostic Module (SDM) operates under the “UART Protocol” which is accessed through P.I.N. 9 on the DCL. This also will not show up under the Class 2 Diagnostic section in the Tech II. So, this vehicle has three different communication protocols. This is very

important to know because of the way the wiring diagrams are set up. Your wiring diagrams will be broken into different bus sections. When you pull up the diagram for the Class 2 systems, you will not find the E & C bus

components or the UART components.

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Splice Pack 1 Star Connector

Corvette

This is a wiring diagram from GM’s service information or known as eSI. This is available on CD or through GM’s web site for a fee. There are different purchasing options available.

Notice on the image above pin A, on both “Star Connectors”, connects to the DLC. Tagged off of “Start Connector 1” are pins L, M, E, H, B, D, J and G:

• Pin L connects to the HVAC Module.

• Pin M connects to the Body Control Module.

• Pin E connects to the Electronic Brake/Traction Control Module. • Pin H connects to the Electronic Suspension Control Module. • Pin B connects to the Powertrain Control Module.

• Pin D connects to the Radio.

• Pin J connects to the Remote Control Door Lock Receiver. • Pin G connects to the Instrument Cluster.

Tagged off of “Star Connector 2” are pins C, D, and K:

• Pin C connects to the Left Hand Door Control Module. • Pin D connects to the Right Hand Door Control Module. • Pin K connects to the Seat Control Module.

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Notice that the SDM does not show up in this wiring diagram. As we mentioned earlier this module is on the UART bus and would be on a different wiring diagram. This will be very important to understand when you begin to perform diagnostics on these systems. You will also need to have access to your service information to locate the “Star Connectors” because they are located in different locations on all vehicles.

The Class 2 wiring diagram above lists eleven modules. Although there are more than eleven modules on this vehicle, only eleven of them are operating on a Class 2 protocol. If you were to perform a communication request with your scanner all eleven modules should respond to that request. If you were to only show ten modules responding and according to your wiring diagram there were eleven Class 2 modules, you would know that there was a

problem. Generally, you would then have “U” codes stored in one or more of the other modules, indicating that the module not listed is not on board for one reason or another.

For example, let’s say the Instrument Panel Control Module (IPC) was failing for some reason. When you went into “Message Monitor” or “DTC Check” in your scanner, IPC would not show up on the list. It would only

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multiple of the ten models indicating that there was a problem with the IPC system. The other modules are reporting that the IPC has not sent a “State of Health” message in the last 5 seconds, indicating that the IPC is “Off Line” for one reason or another. You would then need to refer to your service information to trouble shoot the problem.

Both Star Connectors on a Corvette

Located under the passenger side of the dash next to the PCM

Pictured above are the PCM and the two “Star Connectors” on the Corvette. As we move on, we will show you some pictures of the Cadillac Escalade. The Escalade has a “Star Connector” similar to the Corvette. It also has a different style “Star Connector” which is referred to as a “Double Star Connector”. This is actually two “Star Connectors” back-to-back. So, the Escalade actually has three “Star Connectors”, compared to the Corvette which has two. As you begin to see newer vehicles, you will begin to see more “Star Connectors” on them. It will become very important to

understand what role the “Star Connector” has on the vehicle to help you cut down on your diagnostic time.

Star Connectors

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We are now going to go through a case study on a 2001 Corvette. We are not going to go through the repair side of the study. However, we wanted you to understand why the diagnostic process is important. You will see, as we go through this case study, why it is important to have the proper scan tool, service information and the proper understanding of the Class 2 Message Monitor.

Pictured above is an insert from the GM eSI information system. Notice we are starting our diagnostics at the page titled “Diagnostic Starting Point”. Here you will find some of the important information about the system you are working on. Although most of the time you will find the answer to your problem by following the service information, sometimes you may not. GM has spent millions of dollars to have a very complete information system but they cannot lead you through every possible scenario that you may

encounter.

System Selection Menu (1) 2001 Pass. Car F0: Powertrain F1: Body F2: Chassis F3: Diagnostic System Check

“Use of the Diagnostic System Check will identify and lead the technician to the correct diagnostic procedure.”

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Once you have determined your starting point, move on to step two. Notice that right away we are prompted to connect our scanner, as indicated in step two. You are then asked if the scan tool powers up. This may sound like a minor step but if the scan tool does not power up we know there is probably a problem with the circuit. We would want to make sure there is power on pin sixteen in the Data Link Connector (DLC) and make sure we have ground on pin four and pin five. Preferably on pin four since that is system ground. So, keep in mind that just because your scanner does not power up, it does not indicate that your scanner is the problem.

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Step three tells us to establish communication with the HVAC Control Module, the Body Control Module and the Powertrain Control Module. When looking at step three you may be asking yourself “Why is it important that we have communication with the Powertrain and Body Control Modules when I am looking at a HVAC problem?” This is because all three of these systems are dependant of each other for proper HVAC operation.

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DTC Check

Step four now ask us to perform a DTC check. Can we access the modules to check for DTC’s? Notice the right upper image does list DTC’s in the memory. There is a code in the IPC Module and a code in the PDM/RDCW Module. The right lower image indicates that there are codes in the

PCM/VCM Module, ABS/TCS Module and the DDM/LDCM Module. These two scanner images are from two different vehicles. We wanted to give you a couple of different examples of how the codes would appear on your scanner. Class 2 DTC Check Module (s) DTC (s) Present BCM/BFC/DIM/SBM/TBC No IPC Yes Radio No DDM/LDCW No PDM/RDCW Yes MSM/SCM/DDS No 1 / 7 BCM/BFC/DIM/SBM/IBC

Diagnostic Circuit Check

F0: Class 2 DTC Check

F1: Class 2 Messenger Monitor

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If you are not familiar with the system you are working on and do not know the correct parameter reading, you can refer to the service information. You will notice that the chart is divided into four separate sections. The first being Scan Tool Parameters, next would be Date List, then Units Displayed and finally Typical Data Value.

Scan Tool Parameters:

• This is exactly what the name refers to, the P.I.D. as listed on the scanner.

Data List:

• This indicates whether the P.I.D. is an Input, Data or if the P.I.D. is for Module Information.

Units Display:

• This indicates how the information will be displayed. I.e. on/off, counts, temperature, etc.

Typical Data Value:

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We will now turn our attention to testing the “Data Bus” communication at the Data Link Communication Connector with our Lab Scope.

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When we were going through our case study on the Corvette one of the steps asked us to verify that we had scanner communication. If not, we were

instructed to check pin two for battery voltage then, pin four and five for ground. But, what would we do if we had the proper voltage and ground but still had no communication? On the next page we will discuss this. This test procedure is somewhat of a GM only test and we explain why in the next paragraph.

There are several different communication protocols that are used on OBDII systems and we will give you a brief overview of them. There are actually four protocols that are mandated by the EPA that can be used.

First is the 1850 Protocol…and there are two of them. • General Motors uses one of them.

Next is the 9141 Protocol…and there are also two of them. • Typically used by the Asian manufacturers.

• Chrysler also uses this on some vehicles.

GM uses pin 2 for their 1850 Protocol. Ford uses pin 2 and pin 10 for the 1850 diagnostics because they use the other 1850 Protocol.

?

No Communication with vehicle Check Diagnostic Link Connector

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When you get into vehicles that use the ISO 9141 Protocol…this will be on pin 7 and 15…the test we are going to use will not work as easily. This is because on ISO 9141 Protocols, the scanner has to request data before you will see activity on these terminals. If you would want to perform this test you would need to have your scanner hooked-up and requesting data. You would then connect your Lab Scope leads to the back-side of the DLC terminals.

Get Out Your DSO!

This is where the Digital Storage Oscilloscope will be used. You will hook-up your positive test lead hook-up to pin two and your negative lead to pin four. Why pin four and not pin five? Even though pin five is a ground, it is the sensor ground. Pin four is preferred because it is system ground.

One of the things we discussed early in the video was the difference between the UART and to Class 2 system. This being that the UART operates on a five volt system and the Class 2 operates on a seven volt system. But, the biggest difference is the speed and the capability of “Multi-Messaging”.

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Notice the “Pulse-Width” is not fixed. In other words the square wave pattern on and off time varies. This is how the system is able to “Multi-Plex”. Meaning it can perform multiple tasks simultaneously.

Notice that even though the key is off and is out of the ignition, we still have activity on the “Data Bus”. Typically on the older Class 2 vehicles you will not see this. The door is open on our vehicle…therefore the Door Control Module is active.

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By-Pass Mode

To go into By-Pass you first would want either highlight the F3 menu and press “ENTER” or you can press the F3 key. This will bring you to the “Tool Options” screen. You will then select “F6: Set Communication By-Pass Mode” from the menu.

The default setting is “Disable”. To select, highlight “Enable” and press “ENTER”. This will then return you back to the previous screen.

Set Communications By-Pass Mode Select one of the following Disable

Enable Disable

By-Pass Mode: Disable

Press (ENTER) to change to Current Mode.

Main Menu

F0: Diagnostics

F1: Service Programming System

F2: View Captured Data

F3: Tool Options

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Why Use the By-Pass Mode?

This will allow you to build the database, on your scanner, for the vehicle you are working on. The database for the scanner is designed simultaneously with the software for the vehicle. Therefore, the scanner knows what data should be available for the particular vehicle you are working on.

This will allow you to see what data is available in a particular set before the ignition is turned to the run position. Notice that you will see an asterisk on the right of the screen next to each parameter. This indicates that there is no communication with the computer at this time. As the key is turned to the run position you will notice that all the parameters will begin to display data.

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Diagnostic Circuit Check

The “Diagnostic Circuit Check” on the UART cars is used essentially to flash code 12, similar to using a jumper to connect the A and B terminals on the ALDL connector. When you get into the OBDII system the “Diagnostic Circuit Check” takes on a whole new meaning. It will allow you access to different components and will allow you to perform in-depth diagnostics.

System Selection Menu (1) 2001 Passenger Car

F0: Powertrain

F1: Body

F2: Chassis

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Where to Start

We will again turn back to our Computer Service Information and begin with the “Diagnostic Starting Point”. General Motors wants you to start at this point, before you begin to perform individual system checks, because this will give you some insight on whether or not the modules are

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The first section you will test is “F0: Class 2 DTC Check”. The example we are looking at in the video has seventeen modules that are reporting on the data bus with the key on.

You do not have the ability at this point to go into individual specific

modules and look at codes. This section is used to determine which modules actually have codes stored in them. You would then record the modules that have codes and access them individually further on during the diagnostic process.

F2: Class 2 Power Mode

Class 2 DTC Check Module (s) DTC (s) Present BCM/BFC/DIM/SBM/TBC No IPC Yes Radio No DDM/LDCW No PDM/RDCW Yes MSM/SCM/DDS No 1 / 17 BCM/BFC/DIM/SBM/IBC

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Class 2 Message Monitor

We will now turn our attention to the “Message Monitor” section in the scanner. The “Message Monitor” will tell you the active status for the module on the bus.

Notice that in the example above we show that all six modules are reporting active. As we turned the ignition to the off position and removed the key, these modules will begin power down and go into an inactive state.

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The number on the right side of the screen also indicates the module status. An even number indicates an active state and an odd number indicates an inactive state.

On the lower left you will notice that there is a “Sleep Mode”. This will allow you completely turn off all the modules on the bus. This is a very important test in the scanner. For example, if you had a parasitic draw on a battery, after you verified the battery and charging system were ok, you would want to go into this section in the scanner and verify that all the modules go into “Sleep Mode”.

Module Status

Sleep Mode

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Sleep Mode

Notice when you press “Sleep Mode” the screen switches to the above image and a timer starts. This indicates that all the modules are asleep…or inactive.

When we insert the key back in the ignition you will notice that some of the modules will become active. Typically when you insert the key 50 to 80 percent of the module will come back on-line.

Sleep Mode

Timer

Class 2 Key On

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When you turn the key to the run position you will see the remainder of the modules become active.

You will notice at the bottom of the screen it says “Ping Module” and “Ping All Modules”. This allows you to isolate specific control modules and

“Ping” them, which is to send a request to them. This allows you to verify that the modules are communicating on the bus.

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Power Mode

We will now discuss the “Power Mode” section. The “Power Mode” will simply tell you what position the computer thinks the ignition is in. Although this may not sound like it is a very important test—it is. The computer needs to know what position the switch is in to determine which modules to activate. This is also a good section to use when diagnosing an ignition switch problem. The switch position should correspond with the position the switch is actually in.

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Above we are showing you different examples of scanner readings while cycling through the ignition switch positions. Keep in mind that this is the position the computer thinks the switch is in.

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We will now go back to the “Message Monitor” and we are going to isolate individual control modules. We will do this by disconnecting the “Star Connector” under the dash and we will install a jumper lead to isolate individual modules.

These images are of a typical “Star Connector”.

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Splice Pack 205

We will now go back to our Service Information System and view the partial schematic for “Splice Pack 205”. Notice that pin D connects to the data link, which will connect to your scan tool and the Theft Deterrent Module. Pin M connects to the Body Control Module.

When the “Star Connector” is plugged in, all the modules are connected on the bus circuit. If we suspected we had a problem with the Body Control Module, we would disconnect the “Star Connector” and install a jumper lead across pins D and M. This would isolate the Body Control Module from the rest of the circuit. We could then perform our tests on the Body Control Module.

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Tech II Display Function

We are now going to go through a quick tour of the display function and give you an overview of the special functions available on the Tech II. We will also cover some of the “Hot Keys” that are available.

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Notice that approximately 3/4 the way down the screen you will see 1/47. This indicates that there are 47 available parameters in this list to view in the “Engine Data 1” packet. To navigate through the list you can use the up and down arrows or you can jump through pages at a time. To do this you would use the left and right arrow keys. The right arrow key will send you down one page. The left arrow key will send you up one page at a time.

You will notice at the bottom of the screen there are menus you can access. These are called “Hot Keys”. The first one listed is “Select Items”. This will allow you to customize a list out of this packet. You can select any three data parameters and create a separate list for them. This will place the three items you selected on top of the screen. They will remain there as you scroll through the other available parameters.

The next “Hot Key” you will notice is “DTC”. By pressing this key, you will go directly into the DTC menu without having to back out of data list you are viewing.

The next “Hot Key’ is the “Quick Snapshot”. This will allow you to take a quick snapshot of your data without going into the snapshot menu. The Tech II with the 32 meg card installed could record up to several hours of data. Keep in mind that the snapshot will only be recording the data list you are in.

Engine Speed 742 RPM Desired Engine Speed 712 RPM ECT Sensor 167 F IAT Sensor 102 F MAF Sensor 11.75 g/s Desired IAC Airflow 11.93 g/s Engine Load 3 % APP Indicated Angle 0 % TP Desired Angle 13 % _________________________ 1 / 47 Engine Speed

Select DTC Quick More Item Snapshot

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We are now viewing the misfire data on the scanner. We have created the misfire on this vehicle for demonstration purposes. We disconnected the ignition coil on cylinder three but, as you will notice, cylinder one is also indicating a misfire. Now, since we created the misfire, we know that only cylinder three is misfiring. So, why is cylinder one indicating a misfire? This is one of the drawbacks with OBDII. Without getting to in-depth with

misfire monitors, basically the PCM monitors misfires by monitoring

crankshaft speed variations. So, when there is a misfire the crankshaft speed will vary and can sometimes indicate that multiple cylinders are misfiring. This is why it is important to not completely rely on the scanner alone for monitoring misfires. You would still need to hook up your ignition or lab scope to verify the actual problem.

Misfire Data

Engine Speed 666 RPM MAF Sensor 10.76 g/s

Misfire Current Cyl. 1 30

Misfire Current Cyl. 7 0 1 / 29 Misfire Current Cyl. 1

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We will now go into the “Special Functions” menu. This is where you will find all the “Bi-Directional” functions such as the Evaporative Emission test, the Cooling Fan tests, The EGR test, etc.

We are going to select the “Misfire Graphic” menu. This will take a quick high level view of all the cylinders. The “Misfire Graphic” menu will count the misfires and display them on a graph. This will allow for easier viewing.

Powertrain

F0: Diagnostic Trouble Codes (DTC) F1: Data Display

F2: Special Functions F3: Snapshot

F4: I/M System Information F5: ID Information

Special Functions

F0: Engine Data Controls

F1: Transmission Output Controls F2: Fuel Systems

F3: IAC Systems

F4: Crankshaft Pos. Variation Learn F5: Misfire Graphic

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As we mentioned before, the misfire on cylinder three is so severe that it is causing the crankshaft speed to slow down enough to make the PCM think that cylinder one is also misfiring.

This is a quick and simple way to check and see if there is a misfire but keep in mind that it is not real specific. For example, you can not determine

whether the misfire is caused from the ignition or a fuel control problem by performing this test alone. You would still need to hook-up your scope to actually perform pin point testing. If you were to access the DTC menu, you would notice that the stored code was a P0300, which indicates a random misfire. This tells you that the PCM did detect a misfire but could not pin point which particular cylinder it was.

Misfire Graphic

Accumulated Current Counters

Cyl. 1 Cyl. 8 Cyl. 7 Cyl. 2 Cyl. 6 Cyl. 5 Cyl. 4 Cyl. 3 0 256

Cycles of Misfire Data 48 Engine Speed 700 RPM Engine Load 3 %

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Body Control Special Functions

We are again going to focus on the “Special Function” menu. This menu deals with all the control tests on the vehicle. Items such as: controlling the horns, turning on the head lights, operating the radio controls, operating the door locks, etc. The majority of these functions from 98 on up are operated through a body control module.

Body Control Module

F0: Diagnostic Trouble Codes (DTC)

F1: Data Display F2: Special Functions F3: Snapshot F4: ID Information Output Controls F0: Light Test

F1: Lamp Dimming Test F2: Miscellaneous Test F3: Rear Defogger F4: Inadvertent Power F5: Power Down Now F6: Miscellaneous Test

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BCM Synchronization

BCM Synchronization is a function that you will need to perform when you replace an air bag. In 1997 GM started producing SDM systems that would set a hard code in the SDM module after the air bag was deployed—this code could not be erased. This all came about after many law suits over air bag problems. Now anytime the air bag is deployed the SDM module must be replaced.

After the new SDM module is installed in the vehicle it must be synchronized onto the Class 2 data bus. If you do not synchronize the module you will have an air bag light on. The earlier systems would set a code 51. The later systems after 98 or 99 will set a code B1001.

To perform the BCM Synchronization you must first clear the codes, then go in and perform the BCM Synchronization with the key on engine off

(KOEO). This will tell the BCM that you have installed a new SDM module. Nothing is actually happening in the SDM module. All the programming operations are performed to the BCM. You will next need to go back and perform an Instrument Panel re-flash, a PCM re-flash and a Theft Deterrent re-flash. Although this process may sound difficult, it only takes about five minutes.

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CANdi Module

Several times in the video we have referenced about Controller Area Network (CAN). By 2007 all vehicles must be CAN compliant. The first vehicles by GM that are CAN compliant are the Saturn ION and the SAAB 93. GM had to make a module to interface with their Tech II to allow it to communicate with these systems. This module is called the CANdi…which stands for Controller Area Network Diagnostics Interface. This module will go in line with the scanner to the DLC.