1979 Chevy K20 P/U Oil and Temp wiring?

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  • 1979 Chevy K20 P/U Oil and Temp wiring?


Answer #1 | 18/12 2013 16:21
Keep this in mind. Gauges are easy. Especially temp and oil. There is only ONE wire for each gauge that actually "tells" the gauge what to display. The other wires are simply 12V and ground. The temp is usually green, connected on the drivers side head between the spark plugs for cylinders 1 and 3(? might be 3&5). Oil is tan? Might be tan/black, and may have changed vs. the later trucks I'm more familiar with. In any case, if you disconnect EITHER sending unit wire from the sending unit, the gauge should peg out over max or under minimum with the key in run. Then, if you ground that same wire, the gauge should peg out the other way. If the gauge responds properly, the sending unit is bad. If the gauge does not respond properly, the problem is the sending unit wire to the gauge, or any of the various connections to the gauges. There is way more to it than that...both oil and temp have had "idiot light" sending units, which will not operate a gauge. Often a parts store will sell you a switch, not a sending unit. The guages and sending units are incredibly robust. They almost never fail. Resist the urge to blame either of them. The likelihood of both failing is almost nothing. The instrument panel connector and flexible circuit board is a very common problem on these trucks in regards to gauges and light issues. I've seen people hardwire them to eliminate this problem, like here: BTW, that websites forum would be a huge help for you if you want further, ongoing help. Edit: A switch turns a light on and off. A sensor varies it's signal. Very large difference.
Answer #2 | 19/12 2013 14:31
Although both gauges have 2 wires each, one of the two wires is always grounded or made common. You just need to remove other connecting wire from the socket, and switch on the engine. If the gauges go to maximum, then they are working fine. If they do not, then you need to change the gauges. If you think there is a wire short, then the gauges will never go to full after disconnecting one of the wires.

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