Hey guys, I have a 98 xj 4 door 4.0 5 speed, I just got it about 2 weeks ago and when I got it, there was no headunit and the gauges on the cluster didn't work, so I got my test light out and checked all the fuses and there all were good, so I pulled the cluster out cleaned the plugs and put it back together still didn't work, I have a airbag light on, I unplugged the air bag module under the drivers seat and gauges still won't work, all the lights work but needles won't, I replaced the ground from rear head stud to fire wall, still nothing, I am lost and searched every where's and can't figure out why it won't work, my head unit is wired up correctly and that won't work either, so I'm not sure why the cluster and headunit won't work, also sometimes my horn would just randomly come on and stay on for a good minute I don't know why either.

 

The instrument cluster and the radio are powered from the IOD fuse in the PDC. THe IC is also powered from fuse F9 in the JB.

I know you tested all the fuses but I do recommend that you replace the IOD outright.

 

I replaced the IOD fuse and f9 and tested it with a test light and gauges on cluster and headunit still doesn't work, and I did the "cluster self diagnostic" and I am not getting a "NO BUs" code on the odo, the odo isn't light up, all the lights work on the cluster just gauges won't.

 

This is probably the same fuse, but I once shorted out my visor lights changing a bulb and had this same issue of no radio and no cluster. I then found that it was a fuse in the fuse block under the hood. Something like a 15 amp?

 

yeah it was a 15 amp mini fuse lol, I wish that was my problem.

 

Does your engine start and run okay?

Has there been any mods under the dash or to the radio?

The only thing the radio and the instrument cluster have in common, besides the IOD fuse, is their ground. Both systems are grounded at G108, which is located on the far left of the dash structure, above the DLC. There are many circuits grounded here.

You can check for continuity to G108 from the instrument cluster connector(s).

I don't have the instrument cluster connector pinouts for the '98 XJ, only the '97 and '99, which differ, so the '98 may match the '97 or the '99.

Below are both connector pinout diagrams. You must make the determination which applies to your '98.

You'll have to remove the instrument cluster and use a digital Ohmmeter to check for continuity between the respective connector ground pin cavity to a bare spot on the dash structure.

You can also check for power from the two 12 Volt power fuses at the connectors. IOD with key OFF and F9 with key to RUN.

The radio ground is through its chassis. The ground circuit goes from the chassis to G108. The radio must be pulled and the connectors left in place while you check for continuity between the radio chassis and a bre spot on the dash structure.

When checking and grounds (above) the battery negative post connector must be removed.

Instrument cluster connectors. C1 is on the left and C2 on the right as you look at the dash.

'97 XJ Inst Cluster Connector pinouts:



'99 XJ Inst Cluster Connector pinouts:



If the ground circuits are intact and your power feed circuits are intact I would suspect the instrument cluster is defective.

 

Yes it starts up and runs great no problems, the guy before me wired in a push button start in the cigarette lighter outlet. I'm not sure if that would have anything to do with the cluster or radio, but thanks a lot for that information I am going to check all of that later today and get back to you.

 

Do you think it could be a bad ignition switch or something? The previous owner says he wired in the push button start because it was cool, but the ignition feels weird compared to other jeeps I've owned, and when it's running I can just pull the key out and it'll stay running lol.

 

I checked the g108 with a multimeter 1 and 6 I got 1.2 I think it's ohms I'm not sure, #1 was bouncing all over the place until it settled down to 1.2 and #6 went to 1.2 in a couple seconds.

 

What kind of meter do youhave, a digital one?

What Ohms scale did you have it set on when you took those readings?

 

Yeah it's a centech digital multimeter and it was on 200 ohms.

 

Set your meter to 2K Ohms and try reading the '99 connectors C1 and C2, unless you're positive your 98 is configured like the '97 connectors.

Best thing you can do is to get a '98 Factory Service Manual and use the wiring diagrams and pinouts in that manual.

Try Pacific Coast Manuals (Google it). THey have pdf download manuals for around $8.00.

 

Ok thanks I'll try both 97 and 99 but what readings should I get, so I know what to look for?

 

With the meter set to 2K Ohms (2,000 Ohms), full continuity will show .000 in the meter window. If set to the 200 Ohm scale it should read 00.0. An open will show 1. in the window in any scale (it will just move the decimal point over for different scales.

If there's any resistance in the circuit the meter wondow will display something other than Continuity or Open.

Example: A 460 Ohm resistor being measured on the 2K Ohm scale will show .460 in the window. The same resistor will show 1. in the window when the meter is set to the 200 Ohm scale.

Generally you shouldn't see more than 5 Ohms in any circuit.

 

I tested it today, I got 002 on c1 on both 6 and 1, a couple times it was jumping up and down until it settled down to 002.