I usually drive my 1983 S3 diesel tuesday to meet friends for pizza and beer. Last week when I left Round Table Pizza I had to use headlights and instrument lights for the 2.5 mile drive home. A mile and a half into the drive I noticed that the temperature was nearing the red zone and the glow plug indicator light was glowing ( not bright like when starting but a low level glow) ......I finished the drive home. The next morning I checked fluids and the fan belt....all was good. So this got me to thinking why did the diesel heat up with the lights on.....I have never seen it get hot before....but usually only drive it during the day. Then I took it for a short drive and after a long idle the temperature was normal. The only thing I could come up with is that the glow plugs were somehow "on" with the lights on. I checked voltage at the most forward plug with various light switch positions. When the headlights were on there was two volts at the plug. When the instrument lights were on ( and the headlights) there was just over 3 volts at the plug. When I turned the key ( with all lights off) to the glow plug position there was a little over 11 volts at the plug. Has anyone experienced this issue? What was the cause? I know I must pull out the instrument cluster out to check wiring. I have the wiring diagram but am perplexed how this situation could occur if the wiring behind the instrument panel is correct. The previous UK owner installed a new wiring harness. I looking for ideas on exactly what to look for. The glow plugs are the newer type. Comments welcomed and thanks in advance.
Jim
Jim
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