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73-87 Chevy _ GMC Trucks => Interior & Equipment => Instrumentation => Topic started by: kfoz on December 24, 2019, 03:18:20 PM
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'73 C20(engine changed in the past)
Trying to get all factory gauges working. I removed the added lower dash oil & temp gauges.
I added a factory tach with the correct gauge housing. I also installed a correct tach circuit board and a new tach harness(NOT CONNECTED YET) Obviously I installed the small factory fuel gauge also.
The mechanical oil gauge does work. Fuel gauge DOES NOT(it is PEGGED past full)
Also, the hazards work fine OUTSIDE the truck but not inside
Turn signals DO NOT work inside or outside.
I have yet to find the proper harness wire for the temp gauge to work.
Suggestions?
Thank you Forum
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A pegged fuel gauge with the needle pointing at ~3:00 o'clock is probably due to an open in the signal lead between the gauge and the tank sender, or the tank sender is faulty or not properly grounded to the frame. Verify that the cluster has the correct printed circuit and that the foils are shiny and clean wherever they make electrical contact. Gradual oxidation plagues the instrument cluster printed circuits.
The dash panel turn/hazard indicators never illuminating may be bad bulbs or oxidation of the printed circuit foils running to the bulbs.
Turn signals not illuminating may be a weak flasher. Try swapping the turn and hazard flashers to see if the symptoms follow the flashers.
The engine coolant temperature sender connects to the gauge through a dark green wire. The factory installed the temperature sending unit in the left cylinder head between cylinders 1 and 3. Look in that general area for the wire.
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Thank you. The printed circuit is brand new, correct for tach and is installed properly. I've done a few of these over the years. I do remember green wire is for temp. Hopefully I can find it! :)
Again, thanks for the response.
Kelly
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Once you find the temp gauge wire you may also have to switch sending units. The sender for the earlier clusters is a different resistance profile than later units, and if you use the replacement listed in most parts books it will make the gauge reading too low.
I'd have to look up the number of the sending uit I used, but when I finally found a matching sending unit (the original parts number is very hard to find) my temp guage now reads about 3/8 scale when the engine is warmed up (195 degree thermostat) and at 1/2 scale I estimate its running about 200 degrees.
Have you checked to see that the black grounding wire is connected to the park brake bracket or other good chassis ground? If that wire is not connected it will cause a variety of instrument panel problems, including flaky turn signal indicators.
Bruce