OT Cherokee speedometer

OT, definitely, but I'm guessing that somewhere in YT land there is someone who knows the answer. Hoping he clicks here...

I have a Cherokee (96 if it matters). The speedometer has become sporadic. It will drop to zero, then zip back to proper speed, back to zero. Etc. Sometimes hold steady for several miles, occasionally zero out for a mile or so, often flap like a windshield wiper. (Never reading higher than actual speed.)

When speedometer at zero, the fuel gauge starts to climb up and up and up. When speedometer reads correctly, the fuel gauge returns to correct level. (Only those two gauges on the cluster of this model).

Will sometimes happen seemingly randomly on smooth roads, but definitely also impacted by bumps.

I assumed a loose connection in cluster as both gauges were loopy at the same time. Partially removed cluster so I could shake, rotate, etc. But no matter how I turn, bump, bounce cluster I cannot make the gauges change. Pulling and tugging (gently) on the wiring harness does nothing either.

If it's a loose connection, it isn't in cluster or the wiring harness near to it. So then where?

Electrical stuff is not my area of extreme brilliance. And the only repair manual I have for it isn't helping me much.

Guesses? Trouble shooting advice?

General web search revealed what?

You have a bad ground circuit.
which one where?

Behind the kick panel? Under the battery?
Under the hood? At the other kick panel?
Rear of the truck?

Ground strap rusted? Missing? Fell off?

I agree that it probably is a bad ground. I would check a wiring diagram,or trace the common ground for that part of the panel. If I could not find a loose connection, which you apparently did already, I would run an extra ground wire to the dash wiring,from a solid ,good ground. Mark.

Try searching online Cherokee forums and Youtube for common problems in that area.

If you will go on the Autozone website, I think you have to register, which is no big deal, that will give you access to the area of the website where you can access wiring diagrams.

They don't have all models, but do have the more popular ones.

If not there, you may have to pay for access on one of the diagnostic sites.

Once you have a wiring diagram of the instrument cluster, look for the circuit that powers both the speedometer and the fuel gauge. Also look for common ground circuits.

That will at least give you a target to shoot for. Still, an intermittent electrical problem is the hardest to find. Be patient and systematic.

I would start by checking the dash
grounds. Should be a heavy one on each
side. Probably behind the kick panels and
if it's at the bottom it's probably
rusted out.

There was a problem with the connector attaching the wiring harness
to the instrument panel. I believe that There was a replacement
connector part made available back when Cherokees were still being
produced. I have a 98 and the oil pressure gauge drops in and out.
One of the few weak points. I have 315k on the original drivetrain
and get 22-26 mpg. Great vehicles!

(quoted from post at 16:34:06 01/29/20) There was a problem with the connector attaching the wiring harness
to the instrument panel. I believe that There was a replacement
connector part made available back when Cherokees were still being
produced. I have a 98 and the oil pressure gauge drops in and out.
One of the few weak points. I have 315k on the original drivetrain
and get 22-26 mpg. Great vehicles!

Click to expand...

^^^This^^^

I had a 99 Cherokee up until recently, I only got rid of it because it had frame rot but it was running great with 275K miles on it.

My speedo and gauges used to drop out randomly. There is a technical service bulletin to change out the connectors in the harness. The gauge cluster has 2 blind mate connectors that mate to the 2 connectors in the harness. The TSB should have the connector part number, it's the same part# for both connectors. I cut the wires one by one and soldered in the new connector which comes with flying leads. If you take your time it's not that hard. It fixed the problem when I was done.

Cherokee and Grand Cherokee are different but I had a 95 GC that did the same thing. It ended up being a cold solder joint on the circuit board inside the cluster. This was a known problem through those years on the GC. I can't tell you which solder joint it was, I re-flowed almost all of them. I could grab the cluster and kind of twist it, or put decent pressure on one side or the other and it would temporarily fix the symptoms, that's when I figured it was inside on the circuit board.

I'll reply here to say thanks to all who responded.

It's fixed now.

The problem was a bad ground, as some suggested. Previously I had suspected a bad ground, but the grounding locations I looked at all seemed good.

But after the replies I once again tried to trace the instrument cluster wires to their ground. I had been looking in the wrong place before, so no wonder I didn't find the problem.

This time I found the correct grounding point. It looked questionable. I tried to clean it up and a wire fell off in my hand. I suspected I had located the problem, but in any case I had to fix that wire no matter what. I did. Then this morning I drove it enough miles to be pretty certain it's truly fixed.

Just for the archives, this was the ground location near the dipstick.

Again, thanks to all.

Is that the dipstick next to the loose nut behind the wheel?