Screwed Up PCM...I Think

[CMK4425]

Ok I completely rewired all the connections at the battery, Had the battery tested and still the same problem exists . The engine will not start at all. I am going to try a junk yard pcm to see if is something else.:tears:

 

[XJFrankenstein]

Most ECU failures are the result of the capacitors going bad. In some cases, you can turn the key on for a minute or two before cranking the motor, allowing the weak capacitors to charge. If this works, then you have a bad ECU. The capacitors can be changed (I've done it on a YJ), but I had to remove the sealer off of the board to get to the capacitors.

 

[kastein]

the 96 and later XJ ECUs are a lot harder to open up and rebuild without special tools. They also don't suffer from the same issues as the older ones, the 95 and earlier ECUs weren't fully sealed so they suffered a lot more from corrosion, especially where the electrolytic caps stuck up out of the potting compound and were exposed to road salt during the winter.

 

[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.

 

[kastein]

I'm not sure, but I'm also not sure why the engine would even run with a blown fuel pump fuse.

 

[Ecomike]

Sounds like some damaged wiring in the harness, that only shorts out when something moves, or when it gets wet.

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.

 

[CMK4425]

It wouldn't run until after the fuse was replaced.

I'm not sure, but I'm also not sure why the engine would even run with a blown fuel pump fuse.