Great to hear that you found it. In my case, it turned out to be the PCM. I’ll write a concluding post about it after this.
Cranks-no-start after battery drain
- Thread starter Marty123
- Start date
Great to hear that you found it. In my case, it turned out to be the PCM. I’ll write a concluding post about it after this.
I thought I’d write a final update now that I’ve finally got the Jeep running again.
I went through quite a few stages during the troubleshooting process. Among other things, I converted the alternator setup to use an external voltage regulator and installed one. After that, the engine ran fine for about 10 minutes, then stalled a couple of times, and eventually went completely dead. It would no longer boot up properly.
A 10A fuse kept blowing, but I noticed that it did not blow when the PCM was disconnected. I then removed and opened up the PCM, and found a couple of obviously burnt chips/resistors on the board.
After that I tried to figure out whether it could be repaired cheaply, but in the end I decided to order a replacement PCM from a company in the US called Drivetech, which I found on eBay. It was a refurbished PCM, programmed for my Jeep model and with my VIN.
It arrived here in Sweden after about two weeks, and after paying VAT and customs fees, I finally had the “new” PCM in my hands.
Did I install and test it without being 100% sure that there wasn’t still an underlying issue, such as a short in the wiring harness? Yes, I did.
And the Jeep started right up.
At first, both the check engine light and the battery light were on, but they went out gradually after a few starts/drives.
So, in summary: the root cause in my case was the PCM. It is still possible that a failed alternator damaged the PCM in the first place, but that part remains a bit unclear.
For now, the Jeep is running beautifully again.
Feel free to ask if you have any questions — there’s plenty more to tell.
I went through quite a few stages during the troubleshooting process. Among other things, I converted the alternator setup to use an external voltage regulator and installed one. After that, the engine ran fine for about 10 minutes, then stalled a couple of times, and eventually went completely dead. It would no longer boot up properly.
A 10A fuse kept blowing, but I noticed that it did not blow when the PCM was disconnected. I then removed and opened up the PCM, and found a couple of obviously burnt chips/resistors on the board.
After that I tried to figure out whether it could be repaired cheaply, but in the end I decided to order a replacement PCM from a company in the US called Drivetech, which I found on eBay. It was a refurbished PCM, programmed for my Jeep model and with my VIN.
It arrived here in Sweden after about two weeks, and after paying VAT and customs fees, I finally had the “new” PCM in my hands.
Did I install and test it without being 100% sure that there wasn’t still an underlying issue, such as a short in the wiring harness? Yes, I did.
And the Jeep started right up.
At first, both the check engine light and the battery light were on, but they went out gradually after a few starts/drives.
So, in summary: the root cause in my case was the PCM. It is still possible that a failed alternator damaged the PCM in the first place, but that part remains a bit unclear.
For now, the Jeep is running beautifully again.
Feel free to ask if you have any questions — there’s plenty more to tell.
