+15 Power Supply Circuit

Fault symptom
The alarm is not set off when the ignition is switched on and the alarm is armed.
The car will not start.







Diagnostic procedure
1 Check the anti-theft alarm control module's power supply (+15 circuit).
- Remove the anti-theft alarm's control module.
- Connect the test lamp to pin 10 of the control module's connector and a good grounding point.
- Ignition switch in the "ON" position.

The test lamp should light up.
Does it light up?
[YES] Continue with point 2.
[NO] Check and rectify the wiring between pin 10 of the control module and distribution terminal 159. See "Power and Ground Distribution/+15 power supply". Testing and Inspection







2 Check the engine management system's power supply (+15 Circuit)
- Install the anti-theft alarm's control module.
- Remove the engine control module in question.
- Connect the test lamp to:
- Trionic pin 60 and a good grounding point (4-Cyl.).
- Motronic 2.8.1 pin 27 and a good grounding point (6-Cyl.).
- Motronic 5.2 pin 56 and a good grounding point (6-Cyl. US).
- Ignition switch in the "ON" position. The test lamp should light up.

Does it light up?
[YES] Continue fault diagnosis as described in "Powertrain Management/Computers and Control Systems". Testing and Inspection
[NO] Continue with point 3.







3 Check the wiring harness
Check the continuity of the wiring harness between pin 21 of the anti-theft alarm's control module and
- Trionic control module pin 60 (4-Cyl.)
- Motronic 2.8.1 control module pin 27 (6-Cyl.)
- Motronic 5.2 control module pin 56 (6-Cyl. US).

Is the wiring OK?
[YES] Continue with point 4.
[NO] Repair or replace the wiring harness.

4 Final test
Start the car and check to see if the fault symptom persists.

Does the trouble persist?
[YES] The remedial measure taken was correct or the fault is of intermittent nature.
[NO] Continue as described in "Before Changing the Electronic Control Module". Before Changing the Electronic Control Module