1999 XJ Instrument Clusted Dead...kind of

Ok, I've posted on numerous sites and nobody has given me a solution to my problem. I live in Minnesota and it seems like every winter my instrument cluster stops working. During the summer months, it works just fine. The weird deal is, that all the gauges will work, as long as I'm honking my horn. That's right, I have to honk my horn to check my fuel level. I've cleaned the connectors in the back and applied dielectric grease with no avail, and checked all the fuses. It seems to me like it has to be a grounding issue, so I checked the ground that comes from the fire wall and connects to the engine, that also didn't work. Is there anything else anyone can think of? I'm thinking about getting a new cluster but I don't think that is the problem due to the horn honking issue. As you can imagine, it's getting a little annoying to have to honk every time I want to check any of my gauges. Any help would be greatly appreciated.

Thanks!

It won't work if you push in on the cluster? What about after you've run the heater for a while and gotten everything hot inside? I suspect that the plastic dash shrinks up a little with the cold and ruins the connection to the socket at the back of the cluster.

I tried pushing in on the cluster and that doesn't work, and even when you get it so hot in the cab you have to open the window it doesn't work. The only time it works is if you hit the horn. My thinking is that the horn is somehow grounding the cluster but I'm not sure. I wonder what pin coming out of the back is the ground, maybe I could manually run a ground to the cluster to see if that works.

I'd bet on a ground/power backfeed issue also, hopefully Joe Peters or Tom (old_man) has an FSM handy that can tell you where to look for suspect grounds... I don't have a 99 FSM or I would check.

Have you tried percussive debugging? When you want to read the gauges, whack the top of the dashboard with the heel of your hand and say a few of your favorite four letter words, usually helps with such problems.

Haha! Believe me, a few choice words have been said due to this problem. And the occasional right jab.

check the harness coming out of the firewall, i had a pin break in that connection that caused my lights to only work when something else was on(dont remember what) im wondering if something isnt broken and rattling around in, randomly touching different connectors. sometimes horn, sometimes it actually realigns with where it should be.

Certainly sounds like a grounding issue.

Don't have a 99 FSM, and working up under the dash can be PITA, but I would look for grounds behind the instrument panel.

I took the cluster out last night again and tried to figure out what wire is the ground coming out of the back, but basically I was just guessing. I threw more dielectric grease on there with no avail. Thanks for the ideas.

spurjeep said:

I took the cluster out last night again and tried to figure out what wire is the ground coming out of the back, but basically I was just guessing. I threw more dielectric grease on there with no avail. Thanks for the ideas.

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With the connector in hand, and an ohm meter, check the wires and look for those that have infinite or zero ohms resistance--some will have varying resistance values due to sensor states, but check the zero wires and watch for black color--no guarantee on the color, but black would be logical, or black with a stripe.

joe_peters said:

With the connector in hand, and an ohm meter, check the wires and look for those that have infinite or zero ohms resistance--some will have varying resistance values due to sensor states, but check the zero wires and watch for black color--no guarantee on the color, but black would be logical, or black with a stripe.

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Great advice on a Renix or even pre-96/97 - but this has the potential to nuke electronics on a 96/97+ due to the signals for the gauge cluster being digital. I would say you will be fine if you use only an analog meter with no more than 3V worth of batteries in it, or a digital meter kept on the lowest resistance scale, but if you use an analog meter with a 9V battery or a digital meter on the higher resistance scales you could easily blow things up if they are not properly diode shunted in the ECU/TCU.

kastein said:

Great advice on a Renix or even pre-96/97 - but this has the potential to nuke electronics on a 96/97+ due to the signals for the gauge cluster being digital. I would say you will be fine if you use only an analog meter with no more than 3V worth of batteries in it, or a digital meter kept on the lowest resistance scale, but if you use an analog meter with a 9V battery or a digital meter on the higher resistance scales you could easily blow things up if they are not properly diode shunted in the ECU/TCU.

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Good warning, thanks for catching my error! :cheers:

Thanks, I figured I should say something as I've toasted electronics by using a meter on the wrong thing before... luckily never my Jeep! Otherwise I'd be catching a ride to work for a while.