I’m hoping to get some help from those with some experience with the 1968 400’s electrical. My 1968 has been running great all summer after a few gremlins were taken care of. The latest one is a bit perplexing. When I put the driving lights or head lights on, the gas gauge goes to empty and the red indicator light in the center of the dash comes on which is the high/ low beam I presume. When I work the switch it doesn’t go out nor does the gas gauge come back. I’m assuming it might be the switch but thought I’d do a shout out here as well before tearing into things.

Thanks in advance,

Kevin-

Its a bad ground on your dash. I had the exact same thing happening (except my gas went to 1/2 of what it should be) after the stereo went in. It turned out to be a bad ground on the dash harness, you could push on the dash in the right spot, and everything would work. I hope that helps.

It is definately a bad ground, but remember, there isn't a ground wire on the cluster harness. The ground is completed by the center screw between the gauge pods. This screw captures a metal tab where the bright indicator bulb is located. If you don't have the correct screw, this can sometimes be an issue. The correct screw has a taper below the head that matches the taper in the cluster hole. This allows the screw to bottom out on that tab. If you have a screw that has a differnt head (as mine originally did) it will still fasten the cluster pod tight, but it won't capture that tab to the dash correctly and can result in an intermitten ground.

Thanks Guys:

Daryl, I think you might have nailed it. Iwas attempting to take the bezel out to repair a corner a couple weeks ago and may not have put all the screws back in (repair still needs to be done). I'll check tonight.

Kevin-

Good luck Kevin. I had a similar thing happen to me a couple of months ago. I took the bezel out and all my screws were a bit different. When I put it back, I had the same issue you are describing. After a closer look, I used a screw that had a trim ring at that center spot so it wouldn't "fit" into the taper of the hole. This wouldn't adequately capture the ground tab. A cheap screw kit from Ames solved my problem. While I had mine out, I cleaned all the exposed contacts on my printed circuit board by hitting them with some steel wool. There was a heavy tarnish on them and when I probed them with my multimeter, I had to pierce that tarnish wire. This also goes for the grounds. The circuit has to ground to the back of the gauges and then throught the high beam indicator as described earlier.

Crap....

I purchased a new gauge carrier off ePay, pulled the old dash and transfered gauge cluster over and more issues.

For the gauge lights, I tested each of the ten bulbs, placed them in their twist in holders, tested them in the holders, placed them in the back of the gauge set (PITA)and the end results are:

Directional signal issues, when in "left", light comes on but and lights on car come on in dash but does not go on and off with the relay. When positioned to the right no "dash indicator light" but lights on car comes on with no on/off. The directionals worked before with no instrument indicator lights.
Lsstly the Alternator/Gen light is on.

I had a shop check the alternator and voltage regulator earlier this summer because the headlights were pulsing bright to less bright. They said that they adjusted the voltage regulator?

Any thoughts?

Kevin-

Is the cluster properly grounded?

Hey Gus and Daryl:

Thanks for your thoughts. The Car went into it's climate controlled storage this evening and will deal with the gen light in the spring. The dricetional relay re-healed itself on the way in which makes me think that its tired (signals work). Got to love these old cars and the puzzles the give us.

Will probably have the alternator tested again in the off season. If tests good, will pull the gauge assembly and add a bunch more ground wires to the bolt contacts on the back and see if anything changes.

My best,

Kevin-