jharpe06

Today I was changing out my plugs and plug wires and I disconnected the negative battery terminal like I always do. At some point while changing the plugs and wires, my negative terminal fell down and made contact again. I was tightening the plug on my number 1 cylinder when my wrench made contact with the positive terminal. Big Sparks = Bad JuJu. UH OH!!! I went ahead and finished up the task and tried to start my jeep. All I got was one click like you would if the battery was dead. After that I got nothing. I took the battery and had it tested. It tested good. Therefore, I am pretty sure I fried my ECU or something. Is there any light at the end of the tunnel??? Is there anything I should check or try first? Im not great with electrical stuff regarding cars but ill sure as hell try. If not, I guess she is going to the shop for a diagnosis

https://www.cherokeeforum.com/f5/wro...k-plug-221294/

blueseasons

Not sure I can be of any help. If this was me, the first thing i'd look at would be fuses. Can't hurt.

jharpe06

Well I am going to do that but I'm sure I also need to check the relays but I don't know how to tell if a relay is bad?

blueseasons

I don't recall specifically as I might have looked at the relays once when I bought this Jeep and I haven't since. But in all other vehicles that I have owned. If they are of same shape and size that are all interchangeable. So you can identify a relay that has a function for ignition, or starter, fuel pump, for example and test it with one thats for wipers or something that doesn't deal with starting the vehicle.

dave1123

A headlight relay works most of the time. There may be a fusible link somewhere that's fried. That's a heavy piece of wire that's designed to melt. In the PDC (power distribution center) under the hood, there are 2 heavy red wires in the front with a flat metal link between them. This may be the link. They are mounted on metal screw posts with nuts.

jharpe06

After checking everything from fuses to relays and that fusible link, I couldn't find anything out of place. I finally just reset the ecu about 4 times by disconnecting the negative terminal. On the last reset, I let it sit disconnected for about 2 hours. After I hooked it back up everything fired up and ran great

blueseasons

Good job!

dave1123

I've been told, a good way to do that without waiting the 2 hours is to disconnect BOTH battery cables and touch them together, thus draining the PCM memory instantly. IDK if that works, but that's what I've heard.