Idle Speed/Throttle Actuator - Electronic: Testing and Inspection

DME Control Unit Harness Connector:

Injection Electronics (Motronic Control Unit). Wiring Diagram:

1. With the ignition switch OFF, remove the DME control unit harness connector (control unit is located in the glove Box) see COMPONENT LOCATIONS.
2. Connect a fused jumper between terminal 36 of the DME control unit harness connector and ground.
3. Turn the ignition switch to the run (ON) position.
4. With a fused jumper, MOMENTARILY ground terminal 4 of the DME control unit harness connector.

^ Idle control valve should run. Remove fused jumper from terminal 4.

5. With a fused jumper, MOMENTARILY ground terminal 22 of the DME control unit harness connector.

^ Idle control valve should run. Remove fused jumper from terminal 22.

^ If idle valve runs continue with step 6. If idle control valve does not run, remove the fused jumper and go to step 7.

6. With the ignition OFF, reconnect the DME control unit harness connector. Start the engine and warm it up to normal operating temperature while varying the load conditions.

^ If the "Check Engine" light illuminates and a fault code 1262 is present check brown wire to terminal 15 of of the DME control unit for a short. If a short is present repair or replace as necessary.

^ If no defects are present, an abrupt drop in engine speed might have caused fault code 1262 to set.

7. Remove the idle control valve harness connector.

^ Check between terminal 4 of the DME control unit and terminal 3 of the idle control unit for a short to ground or battery power.
^ Check between terminal 22 of the DME control unit and terminal 1 of the idle control unit for a short to ground or battery power. If either condition is present repair or replace the affected wiring.

Idle Control Valve:

8. Check resistance between;

^ Terminal 1 and terminal 2 of the idle valve = 18 to 22 ohms.
If not replace the idle valve.
^ Terminal 2 and terminal 3 of the idle valve = 18 to 22 ohms.
If not replace the idle valve.

9. Switch the ignition OFF, remove the fused jumper from terminal 36 of the DME control unit harness and reconnect to the DME control unit. With the ignition switch in the run (ON) position make the following voltage measurement at terminal (female half).

^ Red/white wire (terminal 2) and ground = battery voltage
If not check wire to main relay for an open

10. If all measurements are OK replace the DME control unit with a known good part.