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So My issue started 2 weeks ago. I got in the Van to go somewhere And my - lights on the instrument cluster were not working. The temperature gauge had already previously not been working. The switch to turn the lights on the Spring assembly had broke so I replaced the Headlight switch assembly. This fixed the switch problem. The lights on the instrument cluster did not come back on. I have checked all fuses and fuses are good. Everything is working as far as the gages accept the temperature gauge. The only lights that are working are the warning lights such as fasten seat belt, check engine, blinkers, and airbag light. No other lights on the cluster are working I have replaced all the bulbs And still have not fixed it. My original problem is I lost heat So I started off by changing the thermostat switch and then I changed the thermostat and gasket. I made these changes after the cluster issue. I am about to change the water pump but I have the issue with the thermostat gauge not working. Please any help would be appreciated. I have looked online at videos and everything I am finding is for the 99 and above. These are the blinker lights working These lights work when you turn switch on.
Last edited by Red78rooster; December 26th, 2022 at 9:37 PM.
Reason: Checking my wording to better explain problems.
the top right corner of the schematic where you see circles with squiggles in them labelled "ILLUM . LAMPS" ... that's your cluster lamps. The line going to them is the power, and it's labeled "18" for circuit #18.
When you look at the pinout below the cluster, circuit 18 is the grey wire. Measure that wire on your harness to make sure there's power there or use a test light.
Originally Posted by Red78rooster
It only shows it going to interior lights.
Correct. Cluster illumination is usually controlled by the light switch. So make sure you interior lights are good and fuse and all that.
It took me about 5 seconds to find this schematic. You should be able to find the interior lights drawing pretty easily.
I will check that, thank you. Now with the thermostat would that be number 7?
No, circuit 7 is the signal. Again look at the pinout . Circuit 7 (DK GRN) leads to "ENGINE COOLANT TEMPERATURE SENDER (REAR OF ENGINE)"
Thermostats are just valves. They don't have any wires.
Originally Posted by Red78rooster
If I don't have power there also, would that gage not work?
It looks like it gets power from a common rail (connected to pin 9) which it shares with the other gauges, so if that didn't work then none of the gauges would work.
So there are 3 possibilities, and testing is easy. Instructions are all over the internet.
1. the sender is bad. This can easily be tested with a mug of boiling water and a multimeter. Google "coolant sensor resistance"
2. your wiring is bad. Test electrical continuity with a meter or test lamp
3. the gauge is bad. Entirely possible on a nearly 30yo vehicle. If you ground pin 7 , gauge should go all the way hot. If you disconnect it then it should go all the way cold.
So when I hook up test light to ground and then test #7 drk green, the gauge works. So I believe the black wire is the ground, and I spliced into it and took the wire to a ground and nothing is happening.
Was able to find another temperature sensor on the side of the motor that had melted into pieces. I replaced it and temp gauge started working. Still tracing out illumination issue. Thank you mountainman for the helpful advice.
December 26th, 2022, 9:16 PM
Instrument cluster issues 95 G20
