Body Ground and Engine Ground Question

Last year I had trouble with the engine-to-frame ground (was blowing the ECM fuse repeatedly). At that time, I moved the two ECM grounds onto another intake stud on the engine, which already had another ground wire on it. (pass side) Problem solved.

This weekend, I ran a new ground from this engine stud to the frame, and also a new ground from the firewall to the frame.

Both new grounds mounted to existing frame ground mount. Now has two old and 2 new cables on it.

I left both old ground cables in place, cuz they are both mounted in really PITA places. Both look bad. Body to frame cable looks just about worthless.

My question concerns the existing body ground mounting stud on the firewall. Is this a comman ground collection point, like a bus bar, for all the stuff inside the cab, or is this just a stud on the firewall ?

I'm guessing it's just a stud on the firewall, and my new firewall ground is just as effective, as the original ground was when new.

Radio sounds better, fan and lights seem better, etc.

It is my hope that the electrical engineers who helped design the electrical systems in these vehicles placed the various grounding points in the most effective location - best for a variety of reasons (i.e. shortest path, RFI interference, etc.).

So, I would first try to locate any grounds where they were originally designed to be. However, there are likely many other locations equal in electrical conductivity. Perhaps more important than precise location is the integrity of the ground connection.

For all of the various systems to work properly, the engine must be grounded to the frame, electrical distribution, cab and batteries.

Most engine to frame grounds utilize a heavier braided strap than that used for frame & engine to cab grounds. In addition, the radiator core support is used as a ground for the head, turn & park lights, and those grounding points need to be right for the lights to work their best.

Jim

This worked great. Now I have to wires on each side of the engine.
2 engine to frame and 2 engine to firwall area.
hope this helps.:)
Here is my link of my pics.

http://home.dejazzd.com/jkauto/CLEAN...UN%20WIRES.htm

Thanks for the replys, we're all on the same page, but I'm going to re-post the original question :-)

Is the firewall ground stud a common, bus-bar like arrangement, which has a bunch of grounds from the interior on it ??

I can't see this stud from the interior, I think it's buried under the factory sound-coating. Hmmm. Maybe that answers my own question.

My concern is this: I've added additional grounds, BUT, when this firewall ground dissolves (it doesn't look good, now), will I have a major issue, here ?

Still figgerin' out how to access and clean it.

BTW, good pix.

Yes I think to your question. I have read its some type of common ground point either for the ECM or at least to help tie the cab body ground to the engine ground which grounds to frame. If this node has a bad connection it can cause wierd electronic problems for the ECM dash etc.

I THINK (I did not trace both wires) but the drivers battery grounds to the engine and the passangers grounds to the body.

So I added 2 ground cables. 2nd cable on drivers side now goes to body and 2nd passanger side now goes to block near this common node. I probably should add a 2nd engine to frame and to body ground. Tail lights grounds and other stuff ties to frame.

I don't know Jim probably has a good point but my dumb logic is the more grounds the better.

Sailun,

"My question concerns the existing body ground mounting stud on the firewall. Is this a comman ground collection point, like a bus bar, for all the stuff inside the cab, or is this just a stud on the firewall ?"

On my '95, a ground stud is located on the passenger side firewall and one ground strap goes to the head & one to the chassis. It is positioned just underneath the heater hoses that run into the cab.

When removing the nut to replace the well-worn OEM straps, the stud snapped off halfway down the thread. I pulled the floor mat back and discovered that it is not a common ground to anything other than the engine-cab-chassis.

I drilled it out and replaced it with a stud/doublenut/star washer combo and also replaced the straps with 4ga wire. OHM meter tells me that there is zero resistance at numerous points, so I think things will be OK. Everything will then be painted with Rust Bullet to prevent corrosion. I'd post pics if I knew how. Hope this helps.

If there are other ground studs that you are wondering about, let me know & I'll look around as my rig is still in pieces.

-Bill

Perfect answer, Bill. Thank-you, and everyone else who replied.

What all this means is that we can re-locate this body-to-frame ground to any convenient location on the firewall, and still be electrically equivalent.

Like somewhere the condensation from the AC doesn't drip on it, and road salt doesn't spray up on it.

Like where the under-hood light is mounted/grounded.

My 93 has a +/- bus bar located under a cover high on the firewall just left of the rad overflow bottle. There's a couple relays that use it, one for the fuel lift pump, can't recall the other. I can also verify the stud below the heater connections is nothing more than a stud coming off the firewall with no interior wire connections.
This thread will help ensure my Dmax conversion gets well grounded!
Thanks
Arlie

Can someone list, preferably with photos, some of these ground locations? I just scored a really nice 94 Suburban! One owner with only 108K miles! Very straight and very clean. Just trying to work out a few bugs.

Just today, I noticed the volt meter reading about 9 volts while running down the interstate. From time to time it would slide up to about 13, but then drop back down.

I metered from the alternator output stud to negative on the battery and got 13+ volts at idle. The alt also looks relatively new and is an AC Delco unit.

The Delco batteries are dated 5/12 so they aren't too old.

The more I think about this issue, the more I think I have a bad ground issue. I suspect this vehicle hasn't been driven much over the last few years. The tires look new but are date coded 2011.

Driving this thing has probably just loosened up some corrosion or something.

Anyone have any additional thoughts?

Thanks,

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