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Stock JK TechBulletin board forum regarding issues with OE (original equipment) components of the Jeep JK Wrangler (Rubicon, Sahara, Unlimited and X) such as factory suspension parts, engine, transmission, body parts, interior fixtures and the on-board computer.
Couldn't find the coil in the pdf above, so here's a schematic (below). Note that the coil pack has 4 pins, switched B+, and the other 3 pins are for the PCM to intermittently sink (connect to neg ground) like ignition points did in an old-fashioned distributor. Have you checked for codes (e.g. P2305), if not that may provide info to troubleshoot with.
the pdf page 14 has the coil pack layout none of the pins on the connector to the coil pack ground out, even in your diagram the ground is still the block and plugs for the pack... Not sure what I'm supposed to test there maybe I misread or misunderstood the post..... As for ground to the pack the block has good ground, I pulled the PCM apart and no visible damage, just melted coil 2s it the only issue found so far, it's my only car so unless someone wants to tell me exactly what pins on what connectors are to be tested and what to test for I'm going to just give up and go to a shop for the issue because I've chased my tail on this for months and have made zero progress and dumped over 1k into parts to still have an issue, I would have loved to have put 1k into my suspension or something but not even the factory can tell me what to test for it's like if your not a tech they don't want to help you....
That's the first step, that's where every tech will begin with something like this.
Yea it has a random misfire due to the melted pack, put a new pack in and no codes until she melts that pack then random misfire there is no code prior to the pack melting, but I can't be without a car anymore I gave up on her last night so it doesn't matter shop will figure it out I been on here for the past 3 months trying to sort this out, what waste of time
You need a shop that has Witech software which is the Jeep operating software. I keep repeating myself here saying this but the reason is with a million Jeeps out there aging these issues are going to come up in the 100's if not thousands with electronic problems especially if a Jeep is wheeled a lot in wet situations. I still maintain a lot of wiring issues are related to floating voltages caused by bad ground connections. How your coil issue relates I do not specifically know but the fact that you have replaced the part a few times tells us that the issue is high voltage or high current which causes the meltdowns. Have you gone out there on a pitch black night and opened the hood and observed the engine idling? Will see if there is insulation breakdown under high voltage. Old farmers troubleshooting trick.
One last thought: High underhood temperstures can make coils fail. If you have one of those grille things, or anything restricting air flow, that might be the problem.
You need a shop that has Witech software which is the Jeep operating software. I keep repeating myself here saying this but the reason is with a million Jeeps out there aging these issues are going to come up in the 100's if not thousands with electronic problems especially if a Jeep is wheeled a lot in wet situations. I still maintain a lot of wiring issues are related to floating voltages caused by bad ground connections. How your coil issue relates I do not specifically know but the fact that you have replaced the part a few times tells us that the issue is high voltage or high current which causes the meltdowns. Have you gone out there on a pitch black night and opened the hood and observed the engine idling? Will see if there is insulation breakdown under high voltage. Old farmers troubleshooting trick.
Yea I've done that a couple times even with a melted pack no escaping sparks anywhere on the motor that was one of my first thoughts was the ground on the block went bad or i was loosing spark before the cylinder, at this point I've torn the whole thing down it's either the harness or PCM and since a reflash PCM is the same cost as a harness I want a shop to tell me exactly what is messing up before I spend another dime on her
One last thought: High underhood temperstures can make coils fail. If you have one of those grille things, or anything restricting air flow, that might be the problem.
Shit I do have a us flag mesh insert thing, I'll take it out and try that maybe get some poison Spyder louvers
Definitely get rid of the grille insert -- They are terrible in warm climates!
Pulled the grill cover off put it back together and cold started it and let it idle ran ok for 3 mins then idled funny and blew up another $70 coilpack, so it's not over heating from engine temp, engine isn't even into triple digits when it blew according to my temp laser..... I've never had a vehicle cause a problem I couldn't fix this is infuriating on top of paying $80 a day in Uber fees to get to work the damn jeep eats 70 bucks every time I start it now
Referring to the schematic I posted earlier, have you checked resistance to ground at the connector to the coil pack, on all 4 pins.
The 3 pins going back to the PCM should read the same (high) resistance. To be clear, not checking the coil, test the pins on the connector with wiring.
Edit: I'm expecting pin 4, wire K17, will show a low resistance to ground -- which would draw some amount of continuous current through coil #2. But it probably is, or was, an intermittent fault. And when it happens it miss-fires initially, then burns up the coil from too much continuous current. If this is correct (and that's a big if), it points to wiring (K17) that's grounding or a bad PCM. Disconnect C2 at the PCM to isolate the PCM from the wiring and re-check resistance.
05-17-2023, 10:06 PM
