Hey guys, my buddy Paul talks about this place quite a bit, thought I would sign up and see if I can get some help with my Jeep.
I got in a hurry the other day when hooking up some jumper cables and hooked them up backwards. When I realized it, I hooked everything up proper and it cranked but wouldn't fire. I also noticed some smoke coming from the computer area of the firewall. I unhooked the battery, let it sit overnight, and threw another battery in it to see if it would start. It still didn't start (just cranked) and more smoke came from the ECU.
I blew both of the 50A fuses for the alternator but that seems like all of the fuses for now. It's a 2.5 and my computer has 56027 380 on the side, a buddy has one that has 56027 364 on it from a 93. Will these be compatible?
I'm usually very anal about the jumper cable process process but I let my guard down and it's biting me in the butt.
Any 91-95 2.5L YJ computer will fit. The XJ 2.5L will work too but they had Nuetral saftey switches and had security in some of them too. There is a good thread to check the power going into the ecu on pins 3 and 9 and the 30 amp fuse in the PDC for the ignition run start. If you have power to those pins and you have a no start then ecu replacement time. Call my friend Chris, and tell him Que sent you. He will give you a good deal. If you dont have power follow the instructions and they will get you pointed in the right direction:
Looks like I may have found the issue. I looked at all the wires in the harness and everything checked out ok. I plugged the computer back in and after a minute or 2, the ECU started smoking again. I unplugged it from the battery and then unplugged the harness from the ECU.
The pin for the Auto Shutdown Relay came with the plug. I'll slap a new relay in it and button it all back up once I get the new ECU. Here's to hoping it fixes it!
Thanks for all your help! New to this type of system so I appreciate it.
I got my new to me ecu tonight and it fired right up and ran like a champ! Alternator seems to still be charging too. I think I did a lot of extra work but I now know more about the Jeep and diagnosing it's little issues that I may encounter.
Now it's time to button it all back up and take it for a spin