Alan

They aren't all green - look on your relay chart for Turn Signal Relay (location varies by year).

Khaled for your '87 it is relay V.

Alan

olmann

I basically had this same issue that I posted on another thread. Mine showed up after the car had gone completely dead from the key being left on. I was thinking I had an issue within the cluster itself or maybe at the connector going into the cluster. When I pulled the cluster I checked incoming grounds and power at Plug #2. All good. So I took the back panel off of my cluster and put it on a spare one I have. Everything worked! Ok, so I'm thinking that my printed board that supplies power to the cluster lights and gauges is bad. I swapped boards, reassembled and installed. Did a quick check and the same issue was back. Hmmm. As I was thinking about it I realized the one thing that was different when I initially swapped clusters was that there were no cluster light bulbs installed. I pulled the bulbs and checked again and the gauge was back to normal. OK, my issue is something else. So now I decided to check the power and grounds coming in with the gauges plugged in and the power on. The incoming power for the gauge was low but the power for the cluster was fine.

I then traced the wires that fed the gauge back to the CE panel, Plug O. The wires there were reading low also. Following the schematic I found the wires went to Fuse 39 which powers the cluster. I had recently done a Deoxit treatment to all of the fuses and since I had power to the cluster I didn't think there was an issue there. I pulled the 5A fuse and there was some oxidation still and overall dullness. I measured resistance and did see a small amount. I went and got a shiny new fuse and installed. Problem solved! So after many hours of disassembly/reassembly work and following all of the wiring schematics, all I needed to do is make sure I had a nice clean fuse. This just further reinforces everything said here and on other threads about CE panel maintenance. I was happy to have figured this out as I had this issue on another 928 for years that drove me crazy and that I had never taken the time to figure out.

I will post this on my thread also for future searches.

Glad you got your issue resolved, Paul! I would recommend cleaning/replacing your #39 fuse, along with all the others.

merchauser

Brian, glad you got your issue resolved and it sounds like a very similar issue; for MY89 fuse 10 (where I had my issue) is the equivalent to your fuse 39: both are for instrument cluster. For me the issue resided within the flasher relay being back fed somehow.

To be clear, my gauge was never at fault. It was working perfectly and did the job intended. it told me there was an issue in the system, i found it, and the gauge continued on its merry way. kudos to the gauge!

Dr Bob: the gauge was the only indicator of a problem. Should there or might there have been other telltale signs of this 1 volt drop that were too subtle to detect like dimmer lamps etc. ? Would that only apply to circuits related to the flasher or fuse 10? Or is a 1 volt issue insignificant?

dr bob

The symptom you saw with the flasher happened when you pulled fuse 10 with key on/engine running, and power backfed through the flasher and the dash indicator. The flasher itself played no part in the symptom you shared -- low readings on the volt gauge.