P1789

SELECTOR LEVER POSITION SIGNAL (R, D, 3, 2, 1), DRIVE SIGNAL, OPEN CIRCUIT OR SHORTED TO GROUND





Fault Symptom.
Engine idling speed drops when selector lever moved from P or N.

Conditions.
Shorting to ground or open circuit.

Check The Wiring.
Intermittent faults may occur as a result of temporary short circuits and breaks in the wiring. Jiggle the leads at several Places and in different directions to reveal any faults in the wiring harness, including connectors. Observe the multimeter, test lamp or ISAT scan tool while carrying out this check.





Procedure.
1. Check the transmission control module's output signal

- Connect the ISAT Scan tool.
- Turn the ignition switch to on position.
- Select "READ ON/OFF"
- Select "DRIVE". The ISAT scan tool should show OFF with the selected lever in positions P and N, and ON with it in positions R, D, 3, 2 and 1.

Are the readings correct ?

YES: Proceed to point 4.
NO: Continue with point 2.





2. Check the engine management system's input signal

- Unplug the connector from the engine management system's control module.
- Turn the ignition switch to the ON position.
- Connect a test lamp to the connector as follows:
M4.1: to pins 86 and 58
M5.2: to pins 69 and 54

Saab Trionic: to pins 14 and 60.
The test lamp should light up when the selector lever is in the P and N positions and remain off in the other positions.

Is the signal OK?

YES: Continue fault diagnosis in the engine management system and then continue with point 4.
NO: Continue with point 3.





3. Check The Wiring
Check The Wiring for continuity between the transmission control module and the engine management system.

Is the wiring OK?
YES: Continue with point 4.
NO: Rectify the fault and continue with point 4.

4. Final check

Drive the car on test and check whether the fault symptom persists.

Does the fault symptom persist?

YES: Continue as described under "Before Changing A Control Module". Before Changing A Control Module
NO: The remedial action taken was correct.