1955 Cadillac Ground Issues

[Kevin Kenneally]

I have had several issues I believe are related to a ground problem.  I am wondering if I should replace the ground wires?  The license plate lights did not work until I ran a seperate ground wire now they work fine.  The gas gauge works on and off as does the radio and clock??  If I turn the clock hands manually, the clock begins to work.  I had it serviced at the shop in Wisconsin.  I am wondering if I should replace the ground wires??  Since I ran seperate ground wires to the license plate lights I have had no problem, has anyone had to replace ground wires??  Thanks!

[J. Gomez]

I have had several issues I believe are related to a ground problem.  I am wondering if I should replace the ground wires?  The license plate lights did not work until I ran a seperate ground wire now they work fine.  The gas gauge works on and off as does the radio and clock??  If I turn the clock hands manually, the clock begins to work.  I had it serviced at the shop in Wisconsin.  I am wondering if I should replace the ground wires??  Since I ran seperate ground wires to the license plate lights I have had no problem, has anyone had to replace ground wires??  Thanks!

Kevin,

There are no ground wires that run inside the wire hardness; the ground source for all is via the chassis/frame that connects to the negative side of the battery. There are ground straps place on a few locations such as from the firewall to each L and R engine head.

I would start at the source by making sure the braided ground cable from the battery has good metal to metal connections frame and motor. Second check the ground straps. It is always a good idea to place additional ground straps at other locations from the main frame to the body.

The ground for the dash board is mainly from the body, a bad or lose connections here and everything goes haywire. For the gas gauge to work properly the gas tank needs to be properly grounded also, adding a small wire from a good ground source to the plate for the sending unit helps.

HTH

Good luck..!

[The Tassie Devil(le)]

One way to get the grounding correct is to remove and replace each and every grounding wire, terminal and fitting and clean the attaching point to remove any corrosion that might impair the path of current.

Bruce.

[Kevin Kenneally]

Would replacing both braided straps correct the problem or do i have to do more investigating??  It sounds like they are my problem?? 

Thanks, guys!

[The Tassie Devil(le)]

Replacing the factory straps would do it, as that was all that was required in the past, when the metal was brand new.

But, things like the fuel tank, which had insulating material under the retaining straps, may benefit from a separate grounding strap.

My Son has a car and the grounding strap turned out to be the Floor Shifting Cable, and it melted the outer to the inner cable and really messed things up.   Turned out that the grounding straps were there, but corrosion had made them useless.

Bruce.

[DUC]

One way to get the grounding correct is to remove and replace each and every grounding wire, terminal and fitting and clean the attaching point to remove any corrosion that might impair the path of current.

I had to do this for my tag lights.

[Coupe]

When checking the ground straps be sure the metal is clean and BARE. Along with rust and dirt there should be no paint under the connection on both the engine and firewall.

[Kevin Kenneally]

I looked at mine and they are 55 years old and I can see where some new straps could solve my issues.  From what I can tell, there are 2 braided ground straps.  Am I correct?  I have a book from McVey's, $27 for a kit that contains 2 straps..  Just making sure this is correct before I order..  Thanks!

[Kevin Kenneally]

I just had Craig at McVeys tell me to take a jumper cable, attach it to the neg post on battery, bring it inside the car and clamp the other end to a large screwdriver.  Then touch the instrument panel and see if the fuel gauge works.  If it does, he suggested running a ground wire directly.  If it doesnt work, it is a problem with the gauge.  He said '55's are known for gas gauge issues.  He also said to touch the set knob on the clock and see if it starts running.  If it doesnt, I have a clock issue.  If it does, I have a ground issue.  He said the radio does not have a ground issue because the red light comes on every time I turn the radio on...  Thoughts??  I just dont want to screw anything up!

[J. Gomez]

Kevin,

Any electrical place should have similar straps, also similar straps are also available from non-Caddy sites at a fraction of the $$$ just as FYI. Check http://www.fillingstation.com/.

As for you second question, just you could try that and most likely if there is a bad ground at the cluster once you connect the cable you could see some sparks. Not to worry is just because of the difference of potential between the two.

Clamping the cable to any metal area that mate with the instrument panel would be my first choice.

Good luck..!

[DUC]

Are you talking about the braided ground straps going from the valve covers to the fire wall? You can get the from Dorman under the thier HELP! product line. part #60213.

[Jay Friedman]

I might add that a good "general" ground improvement is to scrape off any paint that might be on the surface of the starter where it mates to the flywheel housing as well as the surface on the flywheel housing itself.  Also, clean the bolt that holds the negative battery ground strap to the starter. 

[Kevin Kenneally]

Great info!  Thanks for the help!  I will see if i can solve this issue thanks to everyone for the feedback!  I will post an update..

Kevin

[Kevin Kenneally]

**Update**  This morning I hooked a jumper cable to the negative post of the battery, pulled it inside the car, clamped it to a large screwdriver and touched the set knob on the clock and BINGO, the clock started ticking!!  It was not running when I got in the car but as soon as I touched it with the screwdriver it started ticking.  I reached and touched the instrument panel but the gas gauge did not move.  I didnt start the car, not sure if I needed to.  Also not sure how much gas is in it but I think I determined I have a ground issue.  My question is, do I have the wires to the clock screwed up because I did have it sent out for cleaning to the shop in Wisconsin?  How are the wires hooked up to the clock?  Also, where is the fuel gauge hooked up to see if I can run a seperate ground wire to it?  It worked fine last year and only started acting up last fall.  Thanks again for the help!

[J. Gomez]

Kevin,

Good signs of progress..!

There should be only one red wire to the clock which is always hot +12V. There is the gray wire attached to the lamp socket for the clock light(s) part of the instrument lights wiring.

For the fuel gauge to work you will need to have the ignition switch on the “ING” position telltale light on or engine running for it the register. If it does not move the issue is back to the ground problems at the instrument panel and fuel sending unit.

Since you have multiple issues with grounding the overall suggestion was to care for these first. Once you have them care for troubleshooting other electrical problems would be easier.

Good luck..!

[Kevin Kenneally]

I just pulled the clock out and there are 2 gray wires going to the lights in the back and 2 wires (black and orange) going to the back of the clock.  Is this correct?  When I got in the car this morning, the clock was not running but I have an extra battery and whn I hooked up the jumper cable to the neg post and touched the set knob, she started ticking again!  What does all this mean???

[Kevin Kenneally]

I also started the car and touched the instrument panel but the fuel gauge still did not register.  Where is the sending unit located so I can run a seperate ground to see if it is a bad sending unit or a ground issue?  It is the original sending unit, do the last 55 years??  If not, how do I replace place it to make the gauge work?

[The Tassie Devil(le)]

The Sending Unit is located in the Fuel Tank.

Not sure if your model has an access plate in the trunk floor, or you have to drop the tank to get to it.

I have seen sending units last the life of the car, and beyond, but have also seen them destroyed and not working because the float has become stuck to the bottom of the tank because the tank was left almost empty, and the fuel turned to a mucky mess.

Bruce.

[Kevin Kenneally]

Does anyone know what wires go to the clock and where I need to attach a seperate ground wire for the fuel gauge?

[J. Gomez]

Kevin,

Sorry forgot the ’55 has the orange and red (globe box light) together at the clock, the orange goes to the +12V source so they are correct.

You could make a pig tail with 16g wire with ring/hook terminals at both ends. Removed one of the small screws from the sending unit at the tank and attach one end to it, find a good chassis/frame ground for the other end.

HTH