So I thought I had all my gauges working in my 68 Charger. Temp worked before, I go the gas and oil pressure gauges going. (I thought). I buttoned everything back up (EVERYTHING) and now when I start the car they all slowly creep to the top.

Oil pressure wants to peg right off the bat. Temp and Gas just slowly creep to peg over a few minutes. If the the key is on, and the car is not running, Oil Pressure does nothing, but Temp will read 270, and Gas reads 3/4 tank.

Is this a short to ground somewhere, or no ground or what? I've been working on fixing these this all week, and thought I was done, and now my brain is full. And naturally, I have the entire dash re-assembled now... Garrr!

FWIW - I really thought I found my gas gauge problem when on of the circuit board mounted lights was flashing with the voltage pulse. I just pulled the bulb and connector and the gas gauge started working. When I found this last night, the temp guage would only ho up a little with the key on, to under 170. I had tested the oil gauge earlier this week and everything was fine. I did all this with the cluster stripped down in the car, and just put it all back together this afternoon.

So am I looking at ground short or no ground?

Sometimes my Mopar really drives me nuts.....

The first place I would start is by testing your voltage limiter. Just about every original one that I have come across pegs at 12 vdc for about two seconds or so when 12 vdc is first applied and then starts to pulsate. Even then, the pulsations may rise to around only 3 vdc then spikes again at 12vdc for a couple of pulsations.

Moral of the story? Get rid of that old voltage limiter, get a digital voltage limiter that will give a 12 vdc in with a constant 5 vdc out and re-start from there. There are plenty of sources for a digital version.

Slotts

My bad. You can get a digital voltage limiter for your 68 Charger from Shannon at Redline for under $40.

info@redlinegaugeworks.com

Slotts

Use a solid state limiter. Thats what I have in my 68 charger and my gages work perfect. Except for the fuel gage. Only goes to half tank when my tank is full. I also have a new sender in the tank. I even took the old wiper and installed it on my new pickup and my fuel gage reads the same.
I just live with it.

OK. Just installed my new redlinegauges solid state limiter. Now I get nothing. Grrrrrrrrr......

Recap:

My temp gauge used to work fine. Just no Oil Pressure or Gas Gauge.
I replaced the sender on my oil pressure gauge. It started to work.
After tightening the bolts on the back of the gas gauge, I got a reading of about 1/2 full, which was probably right.

I did all this with the cluster installed in the car. After then re-assembling everything and putting it all back together I had a weird thing where the light next to the gas gauge would flash along with the limiter pulse. I pulled the light and I again got 1/2 tank on the gauge.

After final re-assembly, when I turned on the key, the gas and temp gauges would slowly want to peg. Oil Pressure didn't move. When I start the car the oil pressure would immediately peg, and the gas and temp gauges would also peg if I let the car run long enough.

Installed the new solid state limiter - now gauges don't move at all. Nothing. Key on, car running, doesn't matter. Put the old limiter back in and I got the same peg behavior.

What the heck? I need to start from scratch diagnosing the whole system again with the new limiter? That would blow. How do I know the new limiter even works?

My brain still hurts. Too many variables to figure out. This is getting real old real fast. I could pull the entire cluster again and do everything on the bench, but darnit I did that once (now twice counting the restore I did a few years ago). Yeah,yeah, yeah, I can send my cluster to Redline and they'll do it all up for me. There's only 6 weeks left of summer. I'd really like to drive my car.

I'm really getting frustrated. Any suggestions short of starting all over from scratch with the entire diagnostic procedure?