No Sound, SID Unit Shows Audio Information

No Sound. SID Unit Shows Audio Information

Fault symptoms
No sound.
The SID unit shows audio information.

Probable cause of fault
Blown fuse for amplifier.

Check wiring harness
Jiggle the wiring harness at several points and in different directions to reveal intermittent breaks and short-circuits in the leads. Observe the multimeter, test lamp or diagnostic instrument during the test.






Diagnostic Procedure

1 Check amplifier trigger voltage
- Unplug the amplifier's 39-pin connector.
- Connect a test lamp to:
- pin 12 of the 39-pin female connector and a good grounding point.
- Switch on the main unit. The test lamp should light.

Test results OK?
YES
Continue with point 2.
NO
Repair or replace lead concerned.
Continue with point 4, Final Check.







2 Check "Mute control" lead to amplifier
- Connect a test lamp to:
- B+ and pin 11 of the 39-pin female connector.
- Switch the audio system on and off.
The test lamp should light after approx. 1 sec.

Test results OK?
YES
Continue with Fault diagnosis, general, "Before changing a control module, (65)."
NO
Repair or replace lead concerned.
Continue with point 4, Final Check.







3 Check amplifier power supply and ground.
- Connect a test lamp to:
- pin 1 of the 39-pin female connector and a good grounding point.
The test lamp should light.
- Connect a test lamp to:
- pin 2 of the 39-pin female connector and a good grounding point.
The test lamp should light.
- Connect a test lamp to:
- B+ and pin 21 of the 39-pin female connector.
The test lamp should light.
- Connect a test lamp to:
- B+ and pin 22 of the 39-pin female connector.
The test lamp should light.

Test results OK?
YES
Continue with Fault diagnosis, general, "Before changing a control module, (65)."
NO
Repair or replace lead concerned.
Continue with point 4, Final Check.







4 Final check
- Carry out a function check.
- Evaluate the function check.
- Check that the symptom has not recurred.

Has the symptom recurred?
YES
Continue with Fault diagnosis, general, "Before changing a control module, (65)."
NO
The steps taken to rectify the fault were correct.