Electronic Control Module Terminals Defined

28 Heated Oxygen Sensor 1 Input. The Oxygen Sensor 1

has a heating element. When the engine is not running and the sensor is warmed up it will detect high oxygen content in the exhaust. Its output voltage will be below 200 mV. With the engine running, after the sensor is warmed up its voltage should change rapidly within 50...900 mV. If the sensor is not warmed up, voltage at the terminal will read 300...600 mV.

29 Heated Oxygen Sensor 2 Input. The Oxygen Sensor 2

has a heating element. Voltage of the warmed-up sensor operating in the closed loop mode at part engine load should change within 590...750 mV if the catalyst effi- ciency is normal. If the sensor is not warmed up, voltage at the terminal will read 300...600 mV.

30 Knock Sensor (KS) Input. The KS signal is AC voltage.

Its amplitude and frequency depend on severity of knock.

31 Rough Road Sensor Input. 2.5 volts should always be

present in the sensor circuit. Jolting of the vehicle body when driving on rough terrain causes variations of the sensor signal voltage.

32 Fuel Consumption Output. The ECM supplies low level

voltage signal (about 0 volts) to the trip computer in puls- es, each about 0.9 msec long. High level of the signal is equal to system voltage. Each pulse indicates consump- tion of 1/16000 litres of fuel, i.e. each litre corresponds to 16000 pulses.

33 No Connection.

34 Cylinder #2 Injector Control Output. System voltage is

supplied to the terminal through the injector coil. The ECM shorts the circuit to ground in pulses once per each turn of the camshaft. Injector pulse width is determined by the engine operating mode.

35 Cylinder #3 Injector Control Output. System voltage is

supplied to the terminal through the injector coil. The ECM shorts the circuit to ground in pulses depending on engine speed. Injector pulse width is determined by the engine operating mode.

36 Main Relay Control Output. System voltage is supplied

to the terminal when the relay is OFF. The voltage should be close to zero when the relay is ON. The ECM ener- gizes the main relay after receiving the ignition switch signal (ECM terminal 27). The ECM de-energizes the main relay with 10 seconds delay after ignition is switched OFF.

37 Ignition Feed Input (ignition switch dependent).

System voltage is supplied through the normally open main relay.

38 No Connection.

39 Idle Air Control (IAC) Valve Control Output (Terminal «C»). Voltage at this terminal is difficult to predict.

Therefore it is not measured for servicing purposes.

40 No Connection.

41 Oxygen Sensor 2 Heater Control Output. The ECM

controls the oxygen sensor heater by connecting it to ground. Voltage in this case is close to zero. When no control signal is present, the terminal should have sys- tem voltage.

42 No Connection.

43 Engine Speed Signal Output. This is an output pulse

signal to the tachometer. Its pulse rate is the doubled engine speed. High level of the signal corresponds to system voltage. Low level of the signal is about 0 volts. Signal duty/dwell (pulse period/low level signal duration) ratio is 3.

44 Intake Air Temperature (IAT) Sensor Input. The ECM

uses this circuit to supply +5 volts through the internal resistor to the IAT sensor. The IAT sensor is a thermistor connected to ground through its second terminal. The sensor changes its resistance depending on the intake air temperature. Higher temperatures produce lower sig- nal voltage.

45 Engine Coolant Temperature (ECT) Sensor Input. The

ECM uses this circuit to supply +5 volts through the inter- nal resistor to the ECT sensor. The ECT sensor is a ther- mistor connected to ground through its second terminal. The sensor changes its resistance depending on the engine coolant temperature. Higher temperatures pro- duce lower signal voltage. If the coolant temperature is 0°C, signal voltage should be above +4 volts. At normal temperatures (85...100°C) signal voltage should be below 2 volts.

46 Cooling Fan Relay Control Output. The ECM ener-

gizes the relay by connecting it to ground. The voltage in this case is close to zero. When no control signal is pre- sent, the terminal should have system voltage.

47 A/C Request Input Signal. When the A/C switch at the

instrument panel is in the OFF position, the voltage at the terminal should be close to zero. When the switch is in the ON position, system voltage is supplied to the ECM, provided that other circuit switches are closed (See Fig. 1.10-01).

48, 49 Crankshaft Position (CKP) Sensor Input. When the

engine is cranking, the terminal is supplied with an AC voltage signal of sinusoidal form. Its frequency and amplitude are proportional to the engine rpm. With igni- tion ON and engine not running, voltage at the terminal should be zero if the circuit is OK, and about 1.5 volts if the circuit is open.

50 No Connection.

51 Oxygen Sensor 1 Heater Control Output. The ECM

controls the oxygen sensor heater by connecting it to ground. The voltage in this case is close to zero. When no control signal is present, the terminal should have system voltage.

52 No Connection.

53 Throttle Position (TP) Sensor Input. DC voltage, which

depends on throttle opening angle. This signal may change from 0 to +5 volts. Voltage is usually below 0.7 volts at idle and at wide open throttle (WOT) signal voltage should be above 4.1 volts.

54 Idle Air Control (IAC) Valve Control Output (Terminal «D»). Voltage at this terminal is difficult to predict.

Therefore it is not measured for servicing purposes.

55 Diagnostic Line «K». This terminal is connected to ter-

minal «18» of the immobilizer control module. At the igni- tion switch-on the ECM uses this line to communicate with the Immobilizer. If the ECM receives Fuel Enable signal from the Immobilizer, it enters normal mode of operation to control the system. Otherwise the ECM will not enable fuel injection pulses.

During communication between the ECM and the Immobilizer module this line is disconnected from the DLC. After the communication is over, the Immobilizer module jumps its terminals «18» and «9», thus connect- ing the diagnostic line to terminal «10» of the DLC. This allows the ECM to exchange data with DST-2MM, using this line. Data is transferred as a series of voltage pulses varying from high level (system voltage) to low level (0 V).