Speedo/Odometer Difficult Issue - Need Help!
 

Speedo/Odometer Difficult Issue - Need Help!
Hello Porsche friends,

I have an issue with my speedometer/odometer that I haven't been able to resolve. Any suggestions and/or advice will be appreciated! Here's the details:

- Speedometer and Odometer BOTH stop working when I switch on the car headlights.
- Speedometer and Odometer BOTH work perfectly fine as long as headlights aren't turned on.
- As soon as headlight is switched on the speedometer drops immediately to 0 mph and the odometer also stops moving.
- All the rest of the gauges in the car work properly both when headlight is on and off.
- The speedo gauge lights and the green headlight light all work properly when headlight is switched on.
- There is an aftermarket stereo/amplifier installed in car.
- I took out speedo and sent out to Hollywood speedometer and they were very nice and took a look and said the speedo unit itself was functioning properly. They had suggested and thought maybe it was the ground connection spade accidentally touching the metal backing of the speedo unit. When I plugged in the connections on the back of speedo i made sure the spade connectors were not touching the anything but the connection terminal.

I don't even know where to begin to troubleshoot this and not familiar with there the wiring would be for the speedo unit in the car. I tried looking in the Bentley manual and online but haven't been able to find anyone with this similar type of issue.

Thanks!
Leon
spreeleon is online now Report Post

Year? Mechanical or electronic speedo? If you leave it connected but remove it from the dash (like have a passender hold it) does it still happen? Maybe a short in a wire behind the dash touching it? Maybe a short in your headlight wires?

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