ZJ Grand Cherokee PCM and BCM Electrical problems Part 1 of 2
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- Опубліковано 12 вер 2024
- ZJ Jeep Grand Cherokee electrical PCM and BCM (Body Control Model) electrical problems troubleshooting and solutions, battery drain solutions
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Thanks for the detailed description & video archive. I'll be watching part II next. My issues ('98 Laredo): once our Arizona summer temps go above 95F or if in the direct sun, I lose the following functionality: upon opening door, no interior lights (door activated) but YES push-button lights work fine, except REAR light at hatch; door locks & controller work fine; add key and turn to ACC: ONLY ABS check light comes on, nothing else on the dash, and nothing moves on the instrument cluster (no odometer reading either); fuel pump engages fine, Jeep fires right up like normal. No power windows. Over-head display: No temperature reading "--", but YES Compass is correct, incorrect DTE, and probably reasonable trip meter & MPG readings. Last, Blower fan & vent selection works, but A/C is not cold (green light ON/OFF switch works, just not cold air). Drives fine. Everything else works (did not test wipers, mirror controllers). So Greulichs here in Phoenix troubleshooted when it was dead (not when it was working as well, under ~95F etc. during mornings/nights), and recommended BCM, then if not a fix, instrument cluster, and if not fixed, door lock controllers (Left & Right)... In the middle of having the instrument cluster bench tested for bad solder connections...
Sorry for the late response. Sounds like you are having a PCM (power control module)/ECM (engine control module problem)
In my opinion, the main culprit for these Jeep electrical and engine start issues is the power control module. You can find other videos where people are addressing problems with the circuit board inside the PCMs. Two of the main problems is: corrosion and bad/cold solders.
I know, for a fact, everything in the gauge cluster is controlled by the PCM/ECM. the first time I killed my PCM/ECM, the very first thing I noticed was everything in the gauge cluster was dead, nothing moved, this also includes the odometer.
How I killed my PCM/ ECM, was via the parking/headlight switch. After purchasing my 98 Laredo I noticed some corrosion in same headlight and parklight bulbs’ sockets. After replacing the sockets, I went to turn on the headlights and parking lights. The parklights work fine, as I switched to the headlights “the engine started turning over but not starting LOL” Crazy sh*t right, thankfully I was still in the driveway. Afterwards, I went to start my Jeep, when the key was in the run position I noticed the gas hand wasn't working, no needles jumped, and my odometer reading was all zeros, in my case at least, and also there was no fuel pump initiation noise.
I tried buying a power control module online, Long story short, it was no good. My engine never started. Best place to go is O'Reilly auto parts, I got mine replaced from there three times. First time I paid about $230.00, the other replacements were under warranty because all this happened with 1 year. If you choose this route be sure to give them your odometer reading when ordering the power control module. If not, you'll get A PCM with A bogus reading. The last PCM I ordered someone made a mistake because my odometer read 305,000 miles, But that didn't matter much for me, I built my Jeep for off roading only.
The second time I killed my PCM/ECM was after I inadvertently activated the security alarm, by accidentally hitting the door lock switch after exiting and reentering my jeep. this happened in the auto parts store parking lot, as a matter of fact I killed the PCM/ECM a second time in the very same parking lot. None of the security deactivation methods I found online worked, so I completely covered my door lock/unlock switches/buttons in place with black adhesive sealant so they could never be used again and us a similar method for the headlight switch, so the headlights position could never be used again. As for the headlight/parking light switch, I took the headlight and high being circuit out of the circuit. ask for the headlights, I had to hunt down the wire that provided power to the headlights on the backside of the headlight/parking light switch. After finding the wire I simply cut and stowed it. As for the high beams, they are on a separate circuit and they get their power from the same fuse, in the engine bay fuse box, I think mine fuse was 50 amp labeled AUX. That provides power for the push button cigarette lighter outlet and the high beam switch. The second auxiliary power outlet to the right of my cigar lighter gets its power from a separate circuit and its fuse is in the passenger side, kick panel fuse box.
As for how I got my headlights to work again, I made my own harness. My harness included one fuse holder with a 15 amp fuse, which provided power to an on-off switch, which provided power to an on-off-on switch. As for the on-off-on switch, one (ON) position activated my low beams, the other (ON) position activated my high beams. This worked perfect for me, Even though the switches go bad and need to be replaced every now and again.
In my opinion, the main culprit for these Jeep electrical and engine start issues is the power control module. You can find other videos where people are addressing problems with the circuit board inside the PCMs. Two of the main problems is: corrosion and bad/cold solders.
@@b2zmodz220 Thanks for the details -- I'm sure your experiences will come in handy for me and others some day. So far, I've had my instrument panel/cluster tested & cleaned up, working fine. The BCM was swapped out from an eBay find, which temporarily solved the electrical problems, but had two issues: 1) mileage from previous vehicle now showing on odometer (and presumably not matching w/ the PCM's memory) and 2) VIN probably stored from the previous vehicle (also presumably not matching w/ PCM's memory). One day about 15 days in, I go to unlock rear hatch and alarm goes off ... I had never heard the alarm during my 14 yrs of ownership, and I no longer had key fob function. Tried cycling the key in each lock (3), then into ignition, firing it up (died seconds later, immobilized), then unplugged battery. That BCM now had an alarm "code". So I put in my original BCM, and alarm is gone...however, the PCM (evidently) does not like the current state: immobilized, though alarm is not going off. SOOOOO Jeep dealer is able to remove the alarm code from the PCM, (not the BCM, unable to touch that coding), and now I am back to square one. Luckily, it drives and the weather is now below 90F so I have full function again... until next Summer!
Hey best way to check for parasitic draw is doing an amperage draw test. Put your multimeter in amperage mode. Disconnect negative battery cable, hook your multimeter black lead to the battery POST and then hook your red lead to the negative battery CABLE. Give it at least 20 minutes to let all the modules go to sleep and now you can check your amperage draw. 24-50 milliamps is the normal limit for a vehicle. Anything over is considered a parasitic draw.
YES YES, Thanks
The video content is so excellent, congratulations
Thanks a lot
that bcm is known to flash lights and door locks for no reason and draw .2 amps to death. sometimes they just need to be plugged in again it's just bad design
Thanks man saved time an money
Glad I could help
Hi what unit is responsible for no power to the injector as well as coil.zj 97 please I'm just about to throw in the towel
The PCM/power-control-module is responsible primarily responsible for the injectors and coil. The engine tune/programing is inside the PCM and the tune tells every electrical component what to do and how to do it. This is my professional opinion, thanks. Stay safe.
what type of front springs you got on that jeep
The front springs came with my Rough Country 4.5 inch lift kit.
Jeep runs fine when it does start that's why I ruled out pcm but I really think it's got to do with the anti theft system but don't know where to start .please advise
The security system ties in with the door locks somewhere down the line. I'm not 100% sure, not even 50% sure because schematics are scarce and the repair manual is worthless in my opinion. The guys at oriiely parts pulled up some schematics for me a while back, maybe you have some luck there.
@@b2zmodz220 I tried the whole door lock thing but still no luck I'm actually starting to pull out the dash to see if I can find the module that controls the immobiliser.i think it's the one cutting out power to the coil
Where on a 2016 jku is the bcm?!
??
I'm having the exact same issue with my jeep.
The older jeeps take some patience. Thanks for watching
Where in zj is body control module?
He stated above the driver's left knee, to the bottom/rear of the steering column. You can see his description in the video @7:25
Thanks
There's also something inside of the console don't know what it does it's by the emergency brake
I feel bad for you don't ever order electrical parts on eBay save yourself time and money
It has a head ….singular