First and probably last Jeep

[cmk4425]

I have a 2001 Jeep XJ 4x4 and it has been a never ending pain in my butt :bang: After fighting and finally fixing wonderful misfire issue I now have a bigger problem. I went to start it and when the key is on but not running the fuel pump, a/c compressor clutch and cooling fan turn on and off. When I unplug the PCM it stops. I checked the grounds on the black PCM plug and they are good but the 5 volt prong is reading 9 volts when the key is on. I have a factory service manual and everything points to the PCM. Is there any way to get the PCM checked out? Can I plug a 98 PCM in to troubleshoot? I know it won't run with a 98 PCM. Can I have a 98 reflashed to work in my 01?

[msmoorenburg]

I would first check the p/n on each ecu and verify that they are the same before trying to re-flash at the dealer. From what i've seen you have way too many engine changes for this too work. The 98 xj's still ran a distributor where as you don't.

[slvmart]

Are you sure you don't just have a problem in the PDC ?

[bigjim350]

I have also owned an 01 before. It had tons of problems too.

Sent from my VM670

[cmk4425]

I checked the PDC and everything seems to be ok. I am getting the same voltage on the trigger part of the relay but I guess I could pull it out to see if anything looks bad. I don't see anything while it is in. Thanks.

[cmk4425]

Ok I fixed the Jeep. I started over from scratch and was checking voltage in the PDC and noticed that the fuel pump fuse was blown. I swapped it out and just for S&G I decided to see if it made and difference. What do you know but it is good now. It starts and runs fine. At first the CEL was on but after driving around and turning it off the CEL turned off. I also hooked up the code reader while the light was on and it wasn't showing any codes. Why would a blown fuel pump fuse cause the A/C clutch and fan to kick on and off???? Thanks for the advice.

[slvmart]

Not sure exactly of all the details, as I haven't looked at the wiring schematic. All I know from looking at it originally is that many of the items you were complaining about were all in the same neighborhood in the PDC.

Glad it worked out for you, I wasn't sure it was the problem. It was just the above observation about everything being in the same area of the PDC.

Hopefully, this saved you some money and a lot of aggravation.