Infamous Courtesy/Done Light Problem
 

Hey everyone. New member here. I just picked up a 1998 Grand Cherokee TSi to use as a beach buggy and for camping/hiking.

When I bought it, I knew the courtesy/dome lights weren't working, but was hoping it was just a fuse. When I got home, I tracked down the fuse responsible for the courtesy lights, and sure enough, it was blown. Replaced it, and I thought everything was fine until I realize that the courtesy lights weren't turning off when I took the key out of the ignition and closed/locked the doors (they turn off when the engine is running).

I've searched this forum, and other forums and have tried various fixes to no avail, so I'm trying to figure out what to try next.

So far I've done the following:

1. Made sure the instrument panel dimmer switch wasn't in up/on position
2. Replaced Fuse 16 (courtesy lights)
3. Swapped Relay C for the courtesy lights with the Relay for the cigarette ligher, and even put the Relay from C in the cigarette lighter and the ligher still worked
4. Removed the front passenger door jamb switch
5. Removed the driver door jamb switch (haven't messed with the rear door switches yet)
6. Unplugged the cargo area dome light

None of the above steps did any good. :brickwall:

What's interesting to me, but could mean nothing since I don't have much electrical knowledge is that when I play with the sliding dimmer switch on the dash, by quickly flipping it all the way up, and then back down just below the always on position, the courtesy lights flicker. Also, if I rapidly press the cargo area light repeatedly, the lights flicker then too.

I'm thinking my next step is to replace the headlight/dimmer switch, but I figured I'd see if anyone had any other ideas...

Thanks!

Welcome to CF!

Did you wait long enough for the courtesy lights to "time out" after exiting the vehicle? Also, the rear hatch switch is a common problem. Do the lights come on when you open the door with the engine running and turn off when you close the door again?

I can't find a wiring diagram for your ZJ, but I know my WJ's interior lights work thru the Body Control Module. If you leave a door open long enough without the engine running, they will turn themselves off. If you close the doors with the engine running or the key in accessory, they will dim out quickly. If you close the doors without the key on, as in parking, they will time out in about 3 minutes. The added problem I have with mine is the switches are in the LATCHES so if they don't latch, the lights will stay on, even when driving! My hatch has 2 latches and one decided to not latch and every time I hit a bump, the lights would flash and a chime would go off. Very dangerous at night! The one good thing is if you forget and leave a map light on, it will time out also.

I'm not certain, but I think your hatch switch is on the latch also. You can also check the wire bundle that goes thru the body to the hatch for chaffing or broken wires. If any of the light switch wires are grounded the lights will stay on, although you say they go off with the engine running.

I'm just thinking by typing. I hope it helps.

see if these work and help///

Attachment 276637

Sorry, hadn't had time to check on the points you mentioned until just now. I had read somewhere that even if the door jamb sensors weren't working correctly, there's another module that is supposed to turn the lights off regardless after 10 minutes or so, so I tried waiting 11 minutes and they were still on.

If I have the engine running, and open and close the driver's door, the lights function as expected - I'll have to try to the other doors too.

I think you're right about the hatch switch since I haven't been able to find anything like the door jamb switches on the hatch. I was hoping to not have to take the trim off the hatch to start investigating, but again, with the lights working correctly with the engine running (will confirm the other doors and hatch later) I think I can eliminate the door/hatch switches as the culprit, right?

Thanks, I'll have to see if I can make any sense of this!

I have the same issue and have been thinking it could be the BCM. Did you ever get to the bottom of the problem?

Unfortunately not. I really thought it was the headlight switch since the dashboard lights were flickering a little depending on where I had the interior light slider, and I could get the courtesy lights to flicker by sliding the dimmer up and down, but I replaced the headlight switch and the problem still exists.

My next hunch is the ignition switch but I haven't really started to look into that at all yet. Although, thinking about it now that doesn't necessarily make sense either because the ignition definitely recognizes when I've left the keys in the ignition since I get the warning if I open the door with the engine off and keys in, so maybe it is the BCM... :dunno:

From what I've been reading on the internet, the BCM works as a control unit to synchronize different relays and systems to cut down on wiring harnesses. They seem to be a big issue on these ZJ's. I'm thinking I have my lighting issues narrowed down to this. I also have flickering dash lights and no display on the screen on the center console.

I just hate to throw a $60-$80 part at a Jeep I bought for $600 if it's not going to fix anything.

Would the BCM need to be programmed by the dealer? I've read in some places that it does, but other people have said as long as it's for the right year it's just plug and play. I'd give it a shot myself if it doesn't need to be programmed, but can't be bothered to get the dealer to program it. It could explain the sometimes erratic behavior of the graphic display in the center console - it works most of the time, but occasionally doesn't show which 4x4 option I'm in.

IDK when this started, but my 2000 WJ works on a Can-Bus system where all the different modules "talk" to one another thru the PCM. The PCM sends diagnostic signals to the different modules (BCM, TCM, ABS, etc) at random intervals and sets trouble codes or warning lights when necessary. It's extremely difficult to find the cause for a problem because of this. I pulled the 40 amp fuse for my ABS motor and the VIC started sending me messages that my memory seat had been disabled because the seat belt was fastened. I don't have memory seats and the seat belt WASN'T fastened. Go figure. I put the fuse back in and the message went away.

That's really weird. I haven't heard a lot about WJ electrical problems. Luckily my '01 is just a base model Laredo, not a whole lot to go wrong. This kinda stuff is a lot of the reason why I usually stick to XJ's, they are as basic as can be. I've seen a lot of questions and answers about ZJ BCM issues on other forums, there never seems to be a common problem, and there's never a good answer on how/why/what. Just seems like people end up running out of troubleshooting ideas until that's what's left. Some people have luck with changing it out and some do not.

Well, my 2000 WJ is also a base model 4.0 Laredo. Manual seats, single zone heater, simple radio cassette/CD player without remote amp, the only factory option it has is 245/70R16 tires.

Had the same problem
 

Had the same problem with our 2010 Jeep Cherokee interior lights and other controls. Turned out to be the multi-finction switch which was repaired at no charge by the dealer because we had purchased an extended warranty.

It's the front door key switches. Ask me how I know. No, don't.