best way to ground the instrument cluster?

[tampabronco]

Through the screws that come through the dash?

 

[Flhtrdr]

On mine I used a short self tapping screw in the back of the cluster (made sure not to hit anything) then ran a wire from that screw to another one I put under the dash. Solved my ground issues.

 

[TN1776]

I ran a ground wire from the back of the cluster (one of the existing screws through a lug, crimped to a length of wire), ran it to a spot where I had other stuff grounded to the body. It solved my issues, though theoretically if your dash is well grounded, the contact between cluster and dash should do it too.

 

[Steve83]

The "best" would be a wire soldered into the battery terminal...



...running along the inner fender to the firewall to a grounding stud that penetrates into the cabin...



...with a ring terminal inside for a dedicated ground wire to the back of the cluster (the bare galvanized surface); possibly the ICVR mounting tab screw.



That gives you a nearly-continuous path of copper wire between the cluster & battery (-) post, and good spots on each side of the firewall to tie in others later.

 

[DirtDonk]

I always use the screw that attaches the IVR to the cluster. This way the IVR has the full benefit of the ground.

You usually have to clean up the area underneath to make sure contact between it and the rest of the cluster is sound, but that's pretty easy to do if everything is out of the vehicle.

I also always add a ground to the dash, to the windshield frame and to the firewall. Tied together with a strap running from the engine to the firewall at least.
No matter how good the body looks, often enough the connecting points between one body panel and another are rusty or just no longer making a good bond. Can't have too many grounds.
Except when they're shorts...

Paul

 

[Crawdad]

A good ground wire from gas tank to the frame, from the frame yo the tub, from the tub to the dash, and finally from the dash your cluster. I also grounded the motor block to the frame.

 

[ntsqd]

Using the IVR screw sounds like a great idea. Some internal or external star washers there might be a bonus.

Can have too many grounds if they're in the wrong place(s). They're called "ground loops" and they will play hell with electronics. If there is more than one ground path from anywhere back to the battery you've got a ground loop. Some ground loops are more significant than others. I just avoid them altogether. If you diagram just the grounding it should more or less look like a tree with the battery as the "roots".

 

[DirtDonk]

Good point. I still think of these things as simple Utility Vehicles with nothing fancy added, but these days of high-tech wizardry and lots of creative additions to Broncos, I should probably get away from that blanket statement.
Oh well. It was fun while it lasted. Made me sound all authoritative and adult-supervision like.;D

Paul

 

[Steve83]

That's not what a "ground loop" is. A "ground loop" is an UNGROUNDED circuit because 2 or more points are erroneously "grounded" to each other, forming a loop. You described parallel (or redundant) grounds, which are perfectly acceptable (as long as EACH is capable of carrying the full ground current). Every stranded wire is parallel/redundant because some of the current it carries passes through each strand; same as passing a current through a body panel or frame member with a hole - some current passes on each side of the hole. It doesn't hurt anything.

To fix a ground loop, just connect it to true ground (battery negative post).

 

[ntsqd]

Two different paths to ground will have different impedences and will also act as antenna. Neither of these is a good thing. To imply that a multi-stranded wire is a de-facto ground loop demonstrates a lack of understanding of what a ground loop really is. Having had serious RFI/EMI issues on a dyno's D/A & controls system due to ground loops that took months to fully sort out and required hiring an expert in spite of having an MS-EE on staff, you can keep your definition and I'll keep mine.
Series grounding avoids the problem, parallel grounding invites it.

 

[Steve83]

IDK what dictionary you're using for these words, but you can't "series-ground" anything.
Every conductor acts as an antenna - grounded or not.
There's a difference in RESISTANCE through any 2 paths, but there's also a difference from one moment to another; it's just not SIGNIFICANT unless one path has resistance an order of magnitude higher.
I didn't say stranded wire is a ground loop - I said it's a parallel ground.
Early Broncos don't have dynos D/A & control systems or anything else that might be affected by a ground loop, EXCEPT one that could be easily solved by truly grounding the loop. Certainly not an eB instrument cluster, which is what this thread is (USED TO BE) about.

 

[ntsqd]

They do have EFI and other electronics, and those have the exact same potential for issues with ground loops.

Yes, you can series ground a sequence of components. It's done all of the time. Body to frame, frame to engine, engine to battery; but not also body to battery. To add that last leg is to create a grounding loop and there will be different IMPEDENCES in those two paths. Not all ground loops result in a "floating ground" situation.

 

[boss]

I have battery to engine, battery to body, body to frame, is that OK?

 

[ntsqd]

Yes, as long as you do not add a jumper from engine to frame.

 

[boss]

Thanks. Have read all of the comments I feel better now.

 

[Steve83]

The gauges have nothing to do with EFI.
EFI is not affected by parallel ground paths - I built Frank's '75, my '83, and the '93 I'm working on now with redundant grounding. Ford built many vehicles that way, too, and continues to do so.
Using the body &/or frame as a ground to complete the circuit back to the battery (-) post isn't "series grounding"; it's "grounding".

It won't hurt anything to add a ground strap from the engine to the frame, engine to alternator case, alternator case to battery, battery to frame, battery to body... As long as each one is heavy enough to carry the maximum current that might ever pass through it. The danger is that the "main" ground fails, and the redundant grounds become the only ground path and are overloaded - then, if they're too small, they become heating elements or fusible links.

In the meantime, all those ground paths will have exactly zero effect on anything, other than to IMPROVE electrical functions all over the truck. ;D