Gauge diagnostics

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Davidrad

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Hi guys. I got the instrument cluster lights working on my non rallye 70 swinger. Now to the temp and fuel gauge. I test for continuity on the posts and get nothing. I've tried a few limiters and they don't seem to make a difference. However they do have different resistance. I'm thinking my last limiter failed and broke my gauges. Am I supposed to have continuity through the temp and fuel gauge? I need a testing procedure.
 
Continuity, yes. There has been hundreds of posts on this board start with a search. In general problems with my cluster......

IVR "socket" fingers were not makking contact with board traces. Had to solder jumpers across. If you have a ralley cluster and the IVR is in the fuel gauge, this does not apply (Your fuel gauge should have 3 terminals if the IVR is inside

Gauge stud nuts corroded. Use "real" nuts and tighten/ loosen/ tighten several times to scrub the contact clean

Bad IVR. Replace with a repop solid state unit.

Bad connections / wiring to the senders. This includes the sender end connectors. Of course the senders themselves

You can power a gauge directly with a 1 1/2V D battery(nothing else connected) and it will go part way up scale
 
test for continuity on the posts and get nothing
How are you testing for continuity? An ohm meter (DVM) would be the best choice.
The meters work by heating an element inside the gauge and causing a bimetal strip or spring to move. The element should have some resistance.
 
I put star washers under all the bolts and screws on the circuit board. They add a little more bite to the electrical connections.
 
All early thermal gauges were approx' 20 ohms post to post. In later models the fuel gauge only changed to 13 ohms (extended its life span).
If/when the basic 7805 regulator looses its chassis ground it will pass system voltage straight through from in to out and fry gauges. Original mechanical limiter would simply stop if/when its ground was lost.
The RTE solid state package does have ground fault protection built in its circuitry. Of course it costs more but What do replacement gauges cost? Good luck with it.
 
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