Need help with alt charging gauge
01-05-2021, 06:22 PM
#1
Need help with alt charging gauge
Hello folks,
I decided to pull the instrument pod on my 85 32V to see if I could fix an intermittent fuel gauge and replace all the instrument lights with LED bulbs. Several of the posts on this forum have been extremely helpful in convincing me to even attempt this job and after some trial and error, I think things have worked out OK. Before I pulled the cluster, the fuel gauge worked only a couple of times since I've owned the car. The charging gauge bounced around a lot and the oil pressure gauge tended to read a bit high in my opinion. A few of the lights, like the belt tension and parking lights, etc, didn't work. After looking through the electrical system instrument wiring diagram and the polarity chart kindly provided by a forum member in another post, I've got all the lights working.
After I put the cluster back in the pod, I noticed that the charging gauge was pegged at zero and would not move at all. The oil pressure gauge is now pegged at 5 and does not move below that. I've double checked the copper traces on the circuit "board" and it seems to have good continuity. I did spray some CRC contact cleaner into the gauge before I put it back together, but it was totally dry before I applied power to it.
I guess my question is, can anyone tell me if there is a way to test the gauge while it's out of the cluster? I've thought about the possibility that I attached the connector cable backwards, but the rest of the lights in the cluster worked, so that seems like a remote possibility, but maybe not?
Sorry for the long post, but I wanted to provide as much information as I could to allow you guys to help me figure this out. Thanks so much.
Jesse
I decided to pull the instrument pod on my 85 32V to see if I could fix an intermittent fuel gauge and replace all the instrument lights with LED bulbs. Several of the posts on this forum have been extremely helpful in convincing me to even attempt this job and after some trial and error, I think things have worked out OK. Before I pulled the cluster, the fuel gauge worked only a couple of times since I've owned the car. The charging gauge bounced around a lot and the oil pressure gauge tended to read a bit high in my opinion. A few of the lights, like the belt tension and parking lights, etc, didn't work. After looking through the electrical system instrument wiring diagram and the polarity chart kindly provided by a forum member in another post, I've got all the lights working.
After I put the cluster back in the pod, I noticed that the charging gauge was pegged at zero and would not move at all. The oil pressure gauge is now pegged at 5 and does not move below that. I've double checked the copper traces on the circuit "board" and it seems to have good continuity. I did spray some CRC contact cleaner into the gauge before I put it back together, but it was totally dry before I applied power to it.
I guess my question is, can anyone tell me if there is a way to test the gauge while it's out of the cluster? I've thought about the possibility that I attached the connector cable backwards, but the rest of the lights in the cluster worked, so that seems like a remote possibility, but maybe not?
Sorry for the long post, but I wanted to provide as much information as I could to allow you guys to help me figure this out. Thanks so much.
Jesse
01-06-2021, 10:37 AM
#2
Instructor
If you map out the wiring diagram to the connector pins for the gauge your testing, you will be able bench test, I would ensure the supply is current limited, that can be done by applying supply through a test light but should be enough to make the voltage gauge move for example. If I had to take mine out again I would replace the whole flex ribbon, they are not too much for the S4 but not sure about yours, suspect that is the fault.
02-02-2023, 09:11 AM
#4
Rennlist Member
I’ve since bought this car from Jesse. The dash is high on the list of “improvements” - only the speedo and temp gauges work, there is no night (back) lighting, but most of the warning lights seem to work. Before I pull the cluster, I’m working through grounds and then will refurb the CEP with new fuses and relays.