I just bought a 1998 Jeep Cherokee Sport 4x4 a couple days ago. When I was driving home from work tonight, it started doing something really weird and I am curious if anyone on here has had this happen and what to do about it.

I noticed that the odometer and radio displays were flashing from bright to dim repeatedly. It would do that for a bit and stop, and then start again. When I got home I noticed that the outside emergency flashers were flashing on and off at the same frequency as the lights. You can hear a flasher clicking and when I turn the turn signals on you can hear another one.

I pulled it into my shop and when it was a little darker, I can see that the dash and the interior lights were also blinking on and off. It did this with the key off intermittently for a couple minutes and then it stopped, almost like it used up residual power?

This is really strange and I hate electrical issues so does anyone out there have any thoughts and/or assistance you'd like to throw this way?

Thanks in advance.

 

Whenever really strange electrical issues pop up, it usually means a bad ground connection.

 

Yup exactly that. Many components tie together through splices to common grounds. When those grounds are crappy the power "backfeeds" through other components. Example: my right turn signal was blinking fast, like a dead bulb. When I pressed the brake pedal, it blinked normally. My dome light also flashed lol. Issue was a grounding point on the crossmember that the front passenger seat bolts to.

 

Alright, can y'all tell me where the grounding points are on these, besides the one that you pointed out to me?

 

You may want to see if the Combination Flasher is introducing the problem through the Turn Signal/Hazard Switch (part of the multifunction switch).

The Combination Flasher is grounded at G107, which is located on the far right side of the dash structure, behind the glove box. The other light systems are grounded at G108, which is located on the far left side of the dash structure, near the headlamp switch and combination flasher.

Refer to the JB and PDC pics below.

Pull fuse #12 in the JB and see if the lights you mentioned flash. Fuse 12 is powered when the ignition switch is to RUN.

Pull fuse marked "Combo Flaser" (should say Combo Flasher - LOL). This fuse is powered directly off the battery bus.

 

Thanks, Ken. This is a great start and hopefully this weekend I will get a chance to look at it.

 

Alright, over here at the shop. Started messing with it. As soon as I opened the driver's door it started. Under the hood in the PDC, there is a Siemans relay marked as "Fog Lamp" that clicks when it is flashing. Pulling this relay does not stop it overall as you can still hear it clicking under the dash on the driver's side. Also, pulling the 12 fuse on the fuse panel does not do anything either. It stops after maybe a minute or so but open the driver side door and it starts flashing again.

I am not sure why there is a relay for fog lamp when this Jeep is not so equipped.

 

I am now under the dash. I found what I believe is the combo flasher, which looks like a black box probably 2 or so inches wide by maybe 3/4" thick. There is a pack of wires coming out of it that has a fuse that just doesn't look factory to me. There is a picture of it at the bottom of this post.

When I pull the fuse out, the intermittent flashing ceases, the turn signals work and the emergency flashers function.

At this point, I am wondering if it will be alright at this point. There is a reason I don't like electrical problems and the fact that I can hardly get to anything under the dash doesn't help.

Thoughts, and thanks again for your help as it is much appreciated.

 

I think that black box is the Headlamp Delay Module. If that tap in the pic is around a Red/White tracer wire, the wire comes from fuse 9 in the PDC, which powers the headlamp switch and the delay module.

If you found a relay in the PDC marked "Fog Lamp", I think the previous owner tried to wire in fog lamps. Maybe he tapped into the headlamp delay module power wire for his fog lamps. Relays in the PDC don't come with function markings on them.

Is there a fog lamp switch on the aux switch panel below the climate control panel? If so, does it look factory or does it look like an aftermarket switch?

Leave that fuse out and be on your way. You'll find out what else doesn't work along the way.

 

The relay itself wasn't marked Fog Lamp, but the diagram on the underside of the cover indicated that is what belonged in the slot. The fog light switch appears to be factory but there are no fog lights on the bumper and not even a spot for them in the bumper like my 1999 Sport had. There are a couple holes on the top side of the bumper that look like they could have been drilled for lights, so that is highly possible.

I left the fuse out and buttoned it back up and will see what happens. Hopefully it doesn't give me any further problem.