68 Charger Gauge Problem

[John Milner]

The gauges in my '68 Charger don't seem to be working as they should.  The amp gauge might be working?  When I touch the key, that needle will move some.  The fuel gauge does not work.  The oil and temp gauge don't work either.  I have had the cluster apart and everything looked good.  I tried to clean everything up the best that I could before putting it all back together when I re-faced the gauges.  I put new light bulbs in and they do not work when I turn the lights on.  I have read up some and my fuel gauge may not be working because I did not ground the sending unit.  All I did there was plug the wire on the new sending unit when I installed my new tank.  Does anyone have any ideas to try?  Thanks

[70 sublime]

The gas oil and water temp gauge get their power from the voltage reducer
It drops the 12 volts to 5 volts
Did you check that it works when you had everything apart ?

[John Milner]

No I did not. This is my first Charger gauge cluster to work on. Probably should have sent it off but that was not in the budget. I'll take it back out and test it. The cluster had a home made ground strap fastened to the back of it. Tells me they may have had some troubles with it in the past.

[70 sublime]

The printed circuit part also has the short posts that the wiring harness plugs into it
I have seen the posts come loose from age and pulling the plug off
Another place to check

[Calif240]

John... I'm not as experienced as some on this site, so take this for what it is worth, but I've tackled several gauge issues over the years and have all my gauges working (except ammeter, which I don't care about).

My approach:
1) Verify that you have power (12v) going to the input side of the voltage regulator on the gauges.
2) Verify that you get 5v on the output side of the voltage reducer
3) you can trace all of the circuit board circuits with a 12v supply or any other power source. I used a simple test light with my gauges off to ensure that every connection "lit" when power was supplied at the start of the circuit.
4) assuming you have power to all connections, if you are still having issues, then you may have a ground problem. You should have ground wire going to your voltage regulator, and the overall gauge cluster should be grounded to the dash through the screws and connections. I ended up "jumping" a ground to one connection because of a broken tab.

Hope this helps.

Terry