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/

 

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.

 

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?

 

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.

 

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.

 

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

 

Good job!

 

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.