This 9-pin connector (21) is for use by qualified per- sonnel to access G.E. STATEX III electric propulsion system diagnostic information and data. Refer to Section “E” for additional information.
SPARE CONNECTOR LOCATION
This connector (22) location may be used for optional equipment installed on the truck such as a Modular Mining Dispatch system.
D3-4 24VDC Electrical System Components D03027
ALARM INDICATING DEVICE (AID) SYSTEM
The Alarm Indicating Device (16) is connected to the electrical accessories circuits to provide the operator with a warning indication of a malfunction. This sys- tem consists of up to eight printed circuit cards, located under the passenger seat in the operators cab. The actual quantity of cards will depend on options installed on the truck.
The AID system enables the indicating lights to be flashing or constant. The AID also has the capability of operating an audible alarm along with the light. The eight printed circuit cards are (refer to Figure 3- 2):
• Diode Matrix (With Sound) Card . . . (Slot 1) • Diode Matrix (Without Sound) Card . . . (Slot 2) • Hot Switch Inverter Card . . . (Slot 3) • Hot Switch Inverter Card . . .(Slot 4) (Not Used) • Temperature Card . . . (Slot 5) • Oil Level Card . . . (Slot 6) • Temperature and Latch Card . . . (Slot 7) • Coolant Level and Flasher Card . . . (Slot 8)
NOTE: Each card is identified with a number which corresponds with a mating number on the housing. If cards are removed, make sure card numbers correspond with housing numbers during installation (See Figure 3-2).
The following information briefly describes each card and its function. Refer to Section “R” for circuit com- ponents described below.
Prior to welding on the truck, disconnect the AID system plug-in cards.
Diode Matrix (Without Sound)
The Diode Matrix Without Sound Card (2, Figure 3-2) consists of a series of diodes capable of working with eight different indicator circuits. The indicator light can be a flashing light by connecting it to the 12F cir- cuit or a steady light by connecting it to the 12M cir- cuit. In addition, some of the indicator light circuits are routed through a dimmer module to allow the operator to vary the intensity of the lamps. These
lamps are fed by circuits 12FD (flashing) and 12MD (steady).
When an indicator circuit is not activated, there is no ground circuit for the bulb. When the Indicator detect- ing switch activates the circuit, it grounds the lamp and grounds the flasher circuit through the diodes. Any circuits connected to terminals C1 through C8 will operate in the same manner. The alarm horn is not activated by this card.
Diode Matrix (With Sound)
The Diode Matrix With Sound Card (1, Figure 3-2) works very much like the other Diode Matrix Card, except that it contains extra diodes to activate the alarm horn in addition to the flasher. The circuits con- nected to terminals A1 through A8 operate in the same manner.
FIGURE 3-2. AID SYSTEM CARD ENCLOSURE 1. Diode Matrix With Sound
2. Diode Matrix Without Sound 3. Hot Switch Inverter
4. Hot Switch Inverter (Not Used) 5. Temperature & Latch
D03027 24VDC Electrical System Components D3-5
Hot Switch Inverter
The Hot Switch Inverter Card in slot 3 (3, Figure 3-2) is used to operate and test the service brake indica- tor light. In normal conditions Q4 transistor is off and the Indicator Light is off. When the stoplight switch is activated, 24 volts is sent to pin “E” of the Hot Switch Inverter Card. Transistor Q4 is turned on by this volt- age and, in turn, grounds the service brake Indicator Light. There is no alarm horn operation with this card. A second circuit on this card is used to operate and test the Retard Speed Control indicator light. When RSC is turned Off, transistor Q7 is off and the indica- tor light is off. When RSC is turned on, 24 volts is sent to pin “J” of the card. This voltage turns on Q7, grounding the indicator light circuit.
Hot Switch Inverter Card (Slot 4) (Not Used) Temperature
The Temperature Card is used to turn on the High Oil Temperature Indicator Light. The indicator light tells the operator hydraulic tank oil temperature has exceeded acceptable levels. Normal temperature setting is 204°F (96°C). As the temperature goes up the resistance in the probe decreases providing a ground path for the indicator light and alarm horn.
Oil Level
The Oil Level Card is used to turn on the Low Oil Level Indicator Light to warn the operator engine oil/ hydraulic tank oil level is below acceptable levels. The oil float is connected to a variable resistor. As the oil level decreases, the resistance goes down caus- ing Q3 to turn on, grounding the indicator light and alarm horn.
Temperature and Latch
The Temperature and Latch Card (5, Figure 3-2) has two circuits to operate two different indicating lights. The temperature circuit is controlled by a coolant temperature sensor which decreases electrical resis- tance as its temperature increases. It will have a resistance of approximately 1000 ohms at 185°F (85°C) and 500 ohms at 250°F (122°C). Normal set- ting is 204°F (96°C).
When the temperature is low and the resistance is high, Q1 is off and no high temperature indication occurs. When the coolant temperature is excessive, resistance decreases to a point where Q1 will turn on and ground the flasher through D8, the alarm horn through D12, and the High Temperature Light through terminal D8. R14 can adjust the temperature (resistance) at which the circuit is activated.
NOTE: Some electronic engine controls monitor coolant temperature. If the engine controls monitor the circuit, a 2KΩ resistor is installed to replace the temperature sensor and disable the AID system circuit.
The Latch Circuit monitors the accumulator pre- charge pressure switches. When one of the pressure switches closes, Q5 will be turned off which supplies power to the gate of SCR Q7. With Q7 turned on, Q9 will supply the ground path to turn on the Low Accu- mulator Precharge Indicator Light and sound the alarm horn. The Indicator Light is connected to 12F and will flash off and on. The SCR will remain on until power is removed from the card by turning the key switch “Off”.
Coolant Level/Flasher
The Coolant Level and Flasher Card (6, Figure 3-2) contains two separate circuits. The flasher circuit at the top of the card has Q12 transistor biased to be saturated when no malfunction is present, resulting in there being 24 volt positive output on pin “H” of the card and on wire 12F. When a indicating circuit is activated, the ground side of the circuit connected to card pin “K” is grounded. Q12 will turn off initially and then after a delay, adjusted by R20, will turn on and off to give the intermittent 24 volt output.
The other half of the circuitry on the Coolant Level and Flasher Card operates the Coolant Level Light. The Water Level Probe connected to terminal B11 grounds the 31L circuit when the coolant in the radia- tor is above the probe position. The coolant saturates the probe and electrically grounds the circuit. When the circuit is grounded, Q6 transistor is off, resulting in no indication. When the coolant level drops below the probe, 31L is no longer grounded and Q6 turns on to ground the flasher through D5, ground the Coolant Level Light through terminal D11, and ground the alarm horn through D6. The light and alarm horn will operate intermittently as their 24 volt supply is from circuit 12F, the flasher output.
NOTE: Some electronic engine controls monitor coolant level. If the engine controls monitor the circuit, a 2KΩ resistor is installed to replace the probe and disable the AID system circuit.
Lamp Test
All of the card circuits are connected to the Lamp Test Switch on the overhead display area. In normal operation, these circuits are open and not functional. When the operator pushes the Lamp Test Switch, it activates all the indicator circuits by grounding them. This is used to verify that all lamps are functional.
D3-6 24VDC Electrical System Components D03027
BATTERY EQUALIZER BOX
Most truck control and accessory circuits operate at 24VDC. However, a 12VDC Power Source is avail- able for the cigar lighter socket, power window motors, and AM/FM, communications and dispatch radios.
For this purpose, a battery equalizer system is uti- lized to obtain the required 12VDC and insure that the two pairs of 12 volt, series wired batteries are charged and discharged equally.
The battery equalizer is mounted in a box on the right hand deck. This box also contains the DDEC circuit breakers (when equipped with DDC 4000 engine), 12VDC control relay, 12VDC circuit breaker, and the main battery disconnect switch. (See Figure 3-3.)
Troubleshooting
Refer to the “Battery” information in this section of the manual for detailed instructions regarding proper battery maintenance and service procedures. Prior to troubleshooting the battery equalizer system, inspect all battery circuit connections for excessive corro- sion, loose cables, ground connections etc.
Use the following procedure to check the battery equalizer.
1. Check the circuit breakers.
a. If a circuit breaker has opened, check cir- cuits and repair cause.
b. Reset circuit breaker.
2. Check battery voltage with the battery equalizer connected and the engine running.
a. Verify battery charging alternator output is 27.8 to 28.2 volts.
3. If alternator voltage is outside above limits, adjust voltage regulator as described in “Battery Charging System”.
4. With the engine running, verify voltages at the battery equalizer terminals.
a. Measure the voltage between the 24 volt and 12 volt terminals.
b. Measure the voltage between the 12 volt ter- minal and ground.
5. If the difference between the voltage measure- ments above exceeds 0.75 volts, the battery equalizer is defective and should be replaced.
Always open main battery disconnect switch prior to removing or connecting any wires or cables in the Battery Equalizer box or prior to welding on the truck.
1. Battery Equalizer Box Assembly 2. Battery Equalizer
3. Circuit Breaker 4. Circuit Breaker Panel 5. Battery Disconnect Switch 6. Disconnect Switch Handle 7. 12VDC Control Relay
D03027 24VDC Electrical System Components D3-7
BODY-UP SWITCH
The body-up switch is designed to prevent propul- sion in “Reverse” with the dump body raised. This switch also prevents forward propulsion unless the override button is depressed and held.
The body-up switch, located on the right frame rail ahead of the body guide, must be adjusted to within limits. Improper adjustment or loose mounting bolts may cause false signals or damage to the body-up switch assembly. The switch should be checked daily and the sensing area cleaned of any dirt or metallic dust accumulation.
Adjustment
Adjust the proximity switch bracket to maintain an air gap (Dimension “A”, Figure 3-4) between the sensing area and actuator bracket, of between 0.50 in. (12.7 mm) minimum and 0.62 in. (15.7 mm) maximum. Set up measurement “B” should be approximately 1.00 in. (25.4 mm).
Service
Keep sensing area clean, free of metallic dust and other debris that may damage or inhibit operation of the proximity switch. If the switch is not functioning or damaged the unit must be replaced.