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Jeep Grand Cherokee Electrical Problems



  • doug_rdoug_r Posts: 1

    Have you checked/replaced your pcm. I am having similar problems and looking at several posting sites the pcm keeps coming up as a common problem. It receives and sends signals to many other modules, often resulting in misdiagnoses of other modules being bad when it is really the pcm. It appears that as the pcm ages the potting compound starts to break down and shorting can occur from the assembly screws. Some people have reported fixing the problem by replacing the 1/2" factory screws with 1/4 or 3/8" screws.

    Good luck.

  • :mad: Thanks for the reply! We'll definitely check that out. The latest problem is the A/C not cooling.....seems it never ends.
  • thanks for reply. no i had no chk engine light, and i checked for code by using ignition, showed DONE, so i replaced coolant temp sensor on thermostat housing,still nothing. at this point fan had quit running altogether,unless direct current was put to it from battery,which is how i crippled along for a few days. fuses under hood were o.k.,so i replaced fan relay under headlight for the second time and it is working fine.but i noticed that the relay itsely gets very warm,it looks like they have mounted it on fender well to displace the heat,it is hot enough that you can't keep your finger on it. i'm just wonder if this is the problem with these things.i was wondering if anyone out there has attempted to use a higher amp. relay,seems like alot of drag on engine when it kicks in, i'm no electric expert, but for relay to run that hot seem to me like would cause a failure in it eventually,i will try to find some info on that and put info on here...thanks barryz...
  • tuggajbtuggajb Posts: 646
    do the wires by the fan motor get hot? if so could be a dragging fan motor or bad bearings in motor
  • the wires get pretty warm,but when problem originated shortly after i purchased the jeep i put a new fan motor on it thinking that was why it wasn't working,although even a new fan could be faulty i suppose,i think the fan motor is o.k., i had it hooked up direct from battery and ran fine with that rig on there,the fan motor does'nt get that hot though,i'll keep an eye on that though,i still have the original fan motor,i hooked it direct tth other day and it ran fine also...what a mystery so for,EH !!!
  • barryzbarryz Posts: 43
    when you mount the relay on the fender, did the new relay have in the kit a tube of a creamy substance? The tube has a heat conducting silicone like substance that you spread on bottom of relay before mounting, use liberally, also put some on the spot relay mounts. It helps take the heat of relay and conduct it to bumper, it goes only on bottom of relay. When my mechanic put relay in, the tube was in the kit that came from dealer. Do not use a substitute relay, this part is actually not a relay but much more sophisticated, it will actually control the speed of fan, from zero speed, to slow, to fast, depending on what the pcm tells it to do.
  • I own a 2005 cherokee and my lights also flash if I manually turn them on in daytime
  • gcldeadgcldead Posts: 1
    I have on my 99 GCL a circle w/a key inside and a slash thru it on the cluster and my truck cranks but doesn't go on??? I was told it had to do with the alarm system. can I bypass the oem GCL alarm?????
  • barryzbarryz Posts: 43
    edited August 2010
    This is not an alarm issue most likely. Are your other gauges misbehaving when you crank it? Specifically, is your fuel gauge at or below empty even though you have gas? If so, the likely culprit is your crank position sensor, which is located on top of bell housing and hard to get at. When it fails, vehicle will crank but not start as the signal from crank position sensor(CPS) is shorting out and not sending signal to pcm to let vehicle start. Fuel gauge will read zero, key light on dash will light. It is a very common problem, i do not recommend going to dealer, it will be around $350 if they decide not to rape you. I found a good local repair shop, i mentioned this is what i thought, they checked it out and verified, replaced part and labor about $200, part alone was around 75, which they got at a parts store, not dealer. Unless jeep is on lift its impossible to get at, and even on a lift an experienced mech will have a hard time. The part has to be adjusted after it is mounted, as it uses a magnetic sensor to measure crank position. That key light you see is in the owner manual shown to be part of the theft deterrent system, not alarm. You have a passkey system, which means key has a chip in it which must be recognized by a module behind the keyhole. It is possible that module went bad, not allowing jeep to start, however it is a proven probability that the cps has gone, key modules rarely to never do. If you were to replace that key module, jeep would still not start even if it had been bad, module and chip in key are mated, and a dealer must reprogram key to work, but that is not likely the prob if you also have the fuel gauge showing zero. I went through this last year on my 99 grand cherokee laredo 6 cyl and posted about it on this site either on this link or start problems link.Mine went bad at about 150,000 miles. Please post your results to help others. Important that you interview the mechanic, some are very familiar with grand cherokee problems, thats the one you want, not some hack in a chain store repair bay. When cps goes bad it will not light check engine light or leave a code, which is actually another indicator that it is cps.
  • barryzbarryz Posts: 43
    Very likely you just need some r-134 added to ac system, you can get a can with a guauge to measure at walmart. Follow directions, it's easy. If within a month it fails again, consider buying a can of Super Sealer next to r134 at walmart, add that, then bring r134 back up to full. Don't waste money on can labeled leak sealer, probably won;t fix. I used super sealer last summer after r134 kept leaking and the leak sealer did not fix. the super sealer worked 1 year, started leaking again, added another super sealer over a month ago, and when i use my gauges to check pressure its fine, no need to add. Follow directions. you will need 2 gauges, so buy 2 r134 cans that each come with a gauge. When you add super sealer, entire can is added, use it after your system has leaked to low pressure and is not working. As soon as you have added entire can of super sealer, immediately have the can of r134 with the other gauge and attached it, even if you have good pressure at that point put a few spritzes of r134 in to make sure super sealer does not seal the valve on jeep you attach to, or you will seal the valve shut permanently. The gauge you had attached to super sealer is probably trash now, super sealer may have permanently sealed it, throw it away with empty can of super sealer. You will spend less than 60 bucks on this. My jeep is 1999 high mileage, blowing cold. Sooner or later these additives may hurt your system, but i'm good a year later, 160,000 on jeep now.
  • pad89pad89 Posts: 1
    edited August 2010
    I have own my 2006 Jeep (used bought 2006) for 4 yeras now..but about a month ago it has been having a starting problem..On two occasion, like in the moring, it was not able to start. So, i had the repairer did tune-up. But, it didn't correct the problem...It wont start in the morning, then later like before noon it will start...But the real problem occured, when i drove from Maryland to North Carolina. I was able to drive safely to my destination...but the next morning, i was unable to start the jeep. i tried starting the jeep many times and it wont start.. And, this when on til a week. The jeep wont start...I took it to a really good repairer and he said the eletrical system was the problem....I really need some help if this is true
  • Check to see if you have a diagnostic code. Use the "turn the key in the ignition 3x" trick to find the code. Disconnect & reconnect the battery to see if it makes a difference.

    Could be something as simple as a faulty sensor. Check through this forum & C-Net forums to find similar symptoms. And...if you take the vehicle to a mechanic, attempt to find one that has much experience working on Jeeps (and I'm not talking about a mechanic at a dealership".
  • Hi everyone,

    I am hoping that you all can help me out with this issue. This morning I went to start my 1998 Jeep Grand Cherokee. It stalled at first (which it does sometimes). Then I heard what sounded like a thump. When I tried to start it again, nothing. No power to the instrument panel, radio, not even the dinging sound when the key is put in. There is no power to windows, doors or seat either. When I tried it again, the key ding sound came back for a minute and there was a noise coming from the CD player.

    I have been having intermittent issues with my Jeep Grand Cherokee for the last year or so:

    Moonroof will not open

    Passenger side windows and doors would work intermittenly ( I found that unlocking and locking the doors multiple times got them to work eventually)

    The driver side door would only lock manually.

    A/C worked intermittenly (and would only blow warm air)

    Please any suggestions or ideas are greatly appreciated!
  • tuggajbtuggajb Posts: 646
    how old is the battery? if older than 2 years change that first as that is the cheapest thing you can do could be low cell that is going out
  • My windows won't operate, my doors will not lock from the driver side when driver door is shut. even when the door is ope now, I have to literally mess with the wire boot and stretch it out before anything even works. Now it doesn't matter how much I mess with the boot, the windows won't operate AND the doors will not lock when I try to use the driver side lock. When I use my remote to unlock or lock the doors, all doors will lock/unlock except for the driver side.
  • tuggajbtuggajb Posts: 646
    broken wire in the boot that you was moving a round find it repair troubles gone
  • Thanks, I will definitely look into that tomorrow and let everyone on here know what happens.
  • architectkmparchitectkmp Posts: 14
    edited August 2010
    Update 2010-08-30 19:53

    Hello again. I am here with good news (but with an "asterisk" *).

    As of this week I can report that , so far,
    my electrical problem
    " Re: 2006 GCL Typical Electrical Issues - Electrical Problem with Dash Cluster" has been solved (*).

    After many components being replaced and, with 20/20 hindsight, we now know that some of them were probably OK, but it was difficult to know at that time.

    * Front Control Module
    * Steering Control Module
    * Shift Control Module
    * Ignition Power Module
    * Ignition Switch (2x)
    * Fuse Block

    The last effort by the "team" looking into this problem was the big one:
    the wiring harness.

    The team included:

    Dodge/Chrysler/Jeep dealer (local) --- Service Director
    Dodge/Chrysler/Jeep dealer (local) --- Senior Electrical Technician
    Dodge/Chrysler/Jeep dealer (local) --- Service Adviser
    Chrysler / Jeep (Detroit corporate) --- Customer Service Representative
    Chrysler / Jeep (Detroit corporate) --- 5 star Engineering Support
    and lastly... --- myself

    After all the above components being replaced and the same initial electrical problem still there, it was obvious (to me anyway) that we never found the source of the original problem. All the previous repair efforts have to be credited to a best educated guess. So, the last attempt at repair was to replace two (2) wiring harnesses: one forward of the firewall and the other in the cabin.

    NOTE: it took considerable effort to persuade the Jeep Corporation to replace these components. Many phone calls were made and a lot of coordination and frankly many hours of normal business day working hours were needed to accomplish this. Many thanks to my company for being so tolerant of this saga as we called it. Some things just can’t be accomplished nights and weekends.

    So… the two harnesses were replaced and now after a few days, (queue the heavenly chorus) and so far, no problems are occurring. Though, the final verdict is not in yet, it seems to be fixed. I told the dealership service department, that I will be closely monitoring this and it is not over till, quite frankly, many months of good performance.

    Bottom line today: FIXED BUT NOT CASE CLOSED

    An observation just after repair is that I think my Jeep GC is running better and smoother than when I purchased it from the Jeep dealer (used with 29k). I am now over 80k and the last few days I feel that the Jeep is running so much better and that I am now thinking that this electrical problem was there from date of purchase and just took a little time to reveal itself. If the problem was there at the beginning it makes me wonder whether the original owner noticed the irregularities and just maybe wanted to trade it in. Mechanical problems are one thing but electrical problems are and can be a nightmare.

    If anyone out there is having similar electrical problems and it is pointing at "this module" or "that module", and they are replaced and the problem still occurs... then go straight to the wiring harness, albeit not an inexpensive way, but it may just solve the problem(s).

  • gfhazegfhaze Posts: 1
    Bought mine used in 03' with about 30 K on it, everything seemed fine until the last 3 years. First after an oil change neither the mechanic nor I were able to reset the on-board PC so no matter what, I always got the error message after starting telling me to perform service as though I was due for another oil change, hit reset every day. I tried adjusting mileage in between to no avail.
    Then slowly but surely additional electrical situations crept up. About a year ago I had to go to town for a meeting, shut off my Jeep all was normal went inside, when I came out Jeep was totally dead it seems that the radiator fan came on and stayed on killing my relatively new battery. I was towed and advised that a module had activated, locked on & died.
    A bit after that I experienced very erratic behavior from my fuel gauge. While driving it would go from full to empty and other destinations in between. This lasted for about a week and then my gas needle never rose from empty again. My mechanic said my fuel pump in the tank was failing I would hear a loud noise and the old Jeep would die!
    Still running having to make sure to fill tank to full and use trip meter for about 330 or so miles till next fill up, and remembering to reset the trip meter. Glad I live in the sticks always keep extra gas in the back, more danger for a rear end collision!
    I am hoping for the fuel tank/fuel pump recall to at least resolve that issue, then I will have to shell out for the module repair and hope for the best!
    Funny, in spite of all the crap I do still love my Jeep! :-()
  • About a month ago my odometer digital display and my radio display would blink at the same time and I would hear a loud Pop in my car stereo speakers. Now my RPM and MPH guages have been going crazy and this morning they stopped working during my drive into work. The other gauges seem to be fine. Sometimes when I start my car, I hear a clicking motor turning noise that I believe is related to the guages and the car may not immediately turn over and start but if I wait a few minutes it will then start. What is my problem? Do i need to start with replacing the fuses? or will that be a waste of time? Should I see if my husband will replace the ECIU or PCU?
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