Basic Alarm System

Displays wrongly or not at all

NOTE: The LED must not be fed with 12 V e.g. by bridging to the central relay. Check fuse 14 before commencing investigation.

(Step L1) Checking the LED ground lead




- Ignition off.
- Disconnect the alarm control module (item C/F).




- Disconnect the LED's connectors.




- Connect an ohmmeter between ground and item 1 on the wiring harness 4-pole insulator. The ohmmeter should show approx. 0 ohms.


If the reading is correct:
Continue with step L2.

If the reading deviates:
There is a break in the LED ground lead.
- Rectify the fault or renew the lead.
Replace the LED connector.

(Step L2) Checking the LED signal lead




- Ignition off.
- Connect an ohmmeter between item 1 (ground) and item 4 on the wiring harness 4-pole insulator. The ohmmeter should read infinity.




Next connect a voltmeter as follows:
- Connect between item 1 (ground) and item 4 on the wiring harness 4-pole insulator. The voltmeter should show 0 ohms.

If the reading is correct:
- Continue with step L3.

If the reading deviates:
There is a short to ground or 12 V on the signal lead between item D1 and the LED connector.
- Rectify the fault or renew the lead.
Replace the LED connector.

(Step L3) Checking the LED current feed




- Ignition off.
- Reconnect alarm control module (item C/F).




- Activate the alarm.
- Wait at least 10 seconds.




- Set off the alarm e.g. by opening a front door by means of the inner door handle.
- Deactivate the alarm.




- Connect a voltmeter between item 1 (ground) and item 4 on the wiring harness 4-pole insulator. The voltmeter should read at least 4 V.

If the reading is correct:
The LED is faulty.
- Check the connections. Refer to Fault Alarm Wiring. Checking Leads and Connection

Renew LED.

If the reading deviates:
There is most likely a fault on the control module.
- Continue with Tracing alarm Wiring. Fault Tracing Alarm Wiring
Replace LED connector.