Symptoms and experiences with ground problems

[nkemp]

The purpose of this thread is to document the symptoms and experiences with ground problems.

Some of the ground experiences I've had would not lead you to a bad ground. And bad grounds can lead to all sorts of problems. So if you have info to share, chime in. Suffice to say that this thread should remain an "earthy" conversation.

Bill Robertson has an excellent thread on creating a ground bus in the mods section and a thread on documenting the ground schematic. The bus may be overkill but it works and I added one to my car. Eliminating the ground path through the frame may be one of the key improvements. Plus you get better current carrying capability from the dash area which is worth the effort.

If you have had ground problem experiences, symptoms or solutions (other than posted in the ground bus or ground schematic threads) please add them to this thread for others to learn from.

Nick

[nkemp]

I’ve had multiple known experiences with bad grounds over the years and I suspect some of the other troubles were ground related but fixed themselves before I could chase them down. Here are some of my experiences:


- - I drove the D a couple miles into town. It ran like a champ. I stopped, turned it off and when I went to restart it was DEAD. I mean like someone stole the battery dead. Not a single light or sound. I pulled it back home and when I put the volt meter on the negative terminal and touched the SS panels I had 12Vdc. Bingo … ground problem. First I checked the battery terminal and it was good. Then I loosened & tightened the trailing arm bolt holding the ground wire to the trailing arm… the lights came on and the car ran fine. Note that this bolt was TIGHT. Corrosion had built up enough to stop the current flow even though there was a solid metal to metal connection. I suspect a little galvanic action here.
- - Another time I was driving and the car was running rough. So much s that I almost took it back home to swap for the other vehicle. During troubleshooting I loosened and retightened a ground wire attached to the engine and it smoothed out.
- - A couple days ago the D died as I was going down the highway. A flatbed ride home. At home I tried jumpering out the RPM relay to get the pump to run but no luck. I checked for voltage on the RPM relay’s brown wire and when I checked against the bulkhead ground bolt there was no voltage. But I could get voltage when tested against the negative battery terminal. Once I loosened and tightened the ground wire from the bulkhead to the engine everything came to life
- - On multiple other occasions I’ve had problems where the car ran poorly or not at all but days later was running fine. Personally I prefer that broken things remain broken so that I can figure out the problem. I suspect that bad grounds were the problem.
- - I used to get a fair amount of static on the radio (an aftermarket model). Since the bus it seems much less staticy.
-

- My volt meter always showed low voltage even on a new and charged battery. When the lights came on it would drop more. With the bus installed the voltage remains very constant (I have a rebuilt GM alternator)

Those are some of my experience and are offered up for those who wonder why their car behaves poorly. It may be a ground problem.


Nick

[Bitsyncmaster]

Had a bad ground on my starter relay. Did not cause a problem with my solid state relay but would have caused problems with a standard relay. I found it by accident checking some connections with an ohm meter. Turned out to be bad somewhere in the crimp to the relay terminal but the crimp looked good under examination with the microscope.

I replaced the whole front bank relay grounds with 16 AWG wire and new pins.

[content22207]

The ground junction for the driver's cockpit is woefully inadequate. One single wire carries several devices likely to be used together at the same time:
- Fuel pump
- Instrument cluster, indicator lights, and illumination
- Windshield wiper motor
It also carries the courtesy lights, but they are unlikely to be used at the same time as the above.

Bill Robertson
#5939

[Kenny_Z]

A bad ground to my block was causing misfires at high RPMs, stalling at idle, and hard starting problems. I ran a new 2ga cable from the battery to the transmission to bypass the trailing arm bolt. I added more grounding for the inertia switch and under dash electronics. I'm still planning a few more grounding upgrades.

[David T]

There are 2 big problems with grounding in the Delorean. The first is, many devices are powered and then switched on the ground side. No ground means the device won't work, no return path to the battery for the electric to go. The second problem is the killer. With no return path (ground) and several devices connected to the same point the electric tries to get back to the battery any way it can and it "backfeeds" into the other devices tied to the common grounding point. Makes for weird symptoms. I agree a "grounding buss" is the way to go like Bill suggests but you can make the system work by cleaning and keeping clean all of the grounding points. But it still can't hurt to connect all of the grounding points with a heavy wire. The only disadvantage is a minor weight penalty.
David Teitelbaum

[content22207]

No ground means the device won't work, no return path to the battery for the electric to go. The second problem is the killer. With no return path (ground) and several devices connected to the same point the electric tries to get back to the battery any way it can and it "backfeeds" into the other devices tied to the common grounding point.

Actually electrons flow the other way (from negative to positive). They don't return to the battery via negative grounds -- they return via the positive side.

Bill Robertson
#5939

[Agent Smith]

It would seem to me the difference between conventional current flow versus electron flow are irrelevant to the discussion at hand unless one has ulterior motives...

[content22207]

Inadequate grounding is what causes the inertia switch and Fuse #7 to melt....

Bill Robertson
#5939