1991 LS 400 intermittent radio audio

[ACMX1989]

  I have a 1991 LS 400 that has intermittent audio output issues.  The radio powers up, has display, the CD changer powers up, the audio output is mostly not working but intermittently there is a low volume output.  I swapped the amplifier with a used one but no joy.  Has anyone had a similar issue and if so what was the root cause of the problem and fix?

[RX400h]

11 hours ago, ACMX1989 said:

  I have a 1991 LS 400 that has intermittent audio output issues.  The radio powers up, has display, the CD changer powers up, the audio output is mostly not working but intermittently there is a low volume output.  I swapped the amplifier with a used one but no joy.  Has anyone had a similar issue and if so what was the root cause of the problem and fix?

CoPilot:

Quote

Here are a few potential causes and fixes based on similar experiences from other Lexus LS 400 owners:

1. Phone ECU Issue: Some owners have reported that a defective phone ECU in the trunk can cause audio issues. Disconnecting or checking the phone ECU might help.

2. Corroded Connections: Check for any corroded or tarnished connections, especially at the plugs and connectors. Cleaning or replacing them might resolve the issue.

3. Dry Soldered Joints: Sometimes, dry soldered joints can cause intermittent audio problems. Inspect the solder joints and re-solder if necessary.

4. Radio Fuses: Verify that both the radio and radio fuses are good. One is in the engine compartment and the other under the dash on the driver's side.

5. Speaker Issues: Test the speakers directly by wiring up a test speaker to the speaker connector. This can help determine if the issue is with the speakers themselves

 

[ACMX1989]

  Thank you for the reply copilot.  I checked all the wiring, speakers all ohmed out good, all the voltages were good so no blown fuses. 

  I determined the head unit must be bad, so I found a head unit on Ebay.  I installed it and everything now works.  When time allows I will troubleshoot the head unit and isolate the failing component. 

  I still have other issues to work out, and will post on those topics so others can benefit from my restoration project.

[RX400h]

Thanks!