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Voltmeter problem.

Voltmeter problem.

18delta

Jeeper
Posts
23
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0
Location
Alabama
Vehicle(s)
1986 Jeep CJ7, 258, Dana 30, T5 tranny with Dana 300 T-case. Dana 44 2.73.
After many months of fighting with my stock oil pressure gauge I decided to replace it with a mechanical unit. I decided on the AutoMeter Z series, and installed both oil pressure and voltmeter.
The gauges went in with no difficulty, and both function well EXCEPT, when I switch on my parking or headlights the voltmeter falls to zero.
I checked my wiring (Yellow to "I" and black to ground) the light wiring was connected to the orange instrument light wires and grounded to the panel.
I checked for shorts and found none. The headlights work at full brightness.
Anyone have a starting point?
 
First off, how did the old voltmeter work? You can connect the voltmeter direct to the battery to check its operation.
 
The old voltmeter worked fine. I reconnected it after my "install" and duplicated the problem. Since my first post I isolated the problem to the instrument lights. If I turn the rheostat to "off" (full dim) the voltmeter works as it should. I disconnected the voltmeter and OP lights and still have the same problem. Could there be a short in the circuit without blowing the fuse?
 
Torx..
I think I found my problem. The stock oil pressure gauge had a red (+) a black (-) and a purple (sender) wire connected to it. I thought the black grounded just the oil pressure circuit. Apparently it also grounded the panel light circuit. When I connected it to the chassis the lights and gauges work.
Does that sound right to you? I don't need to build a fire.
 
The CJ wiring circut was designed quite simple and inexpensive. A lot of guys add additional ground wiring to improve the circutry. Steel sheet metal is a poor conductor of electricity, where the ground system is connected to. There is a ground wire from the battery negative to the firewall, if you could run an extension wire from that firewall location to the back of the dash it could help. Also if you could find a wiring diagram it would help let you know where everything is at.
 
Thanks Torx
I have two wiring diagrams, both different and both supposedly for 84-86 CJ7 .
I've got it working for now I'll add some additional grounding soon.
 
I should have mentioned this in my last post-To determine if any additional ground work is needed, you can just add a temporary jumper wire to see if it helps.
 

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