Ok guys. I've got a good one here. I've got an '00 xj 4.0 aw4 with 231. Blah blah BUT it won't start all the time so here are the issues I'm getting... Cranks fine, when it does fire it runs 110% but once I shut it off it won't restart all the time. I get no bus sometimes and other times the cluster works fine. The CPS is a new Napa one that I have tested and its not grounded out. I have also tried 2 other CPS with same issues. I have tried a different ecu I got the same issues. What I've done to try and fix the issues... Clean all connectors under good, connectors under the jeep, cleaned ecu connectors, cleaned the grounds for ecu and motor and other I could find, pull fuse box under the hood and cleaned it all the wires and connectors looked flawless, clean ecu, cleaned connectors under the dash driver side, traced some wire from fuse box under hood and ecu, the other weird thing is when my key is 'on' my aux fan will come on making me think the jeep is in a safety mode or something so it won't overheat if it was running. I did blow a 15a fuse under the hood the other day which caused the fuel pump to not work. But idk if that was just randomly or what. I'm no dummy when it comes to turning wrenches but honestly right now I'm pretty stumped lol the asd relay under the hood will sometimes click and purge almost, the aux fan purges on the same rhythm as the relay. I'm assuming its a grounded out bus wire or something but I have not seem anything but nice looking wires. Wondering if anyone else had any ideas to help me look.

I know this sounds like a common CPS issues but unfortunately I don't think it is at all. The other reason I don't think the CPS is the issue is cause when the cluster doesn't do anything unplugging the CPS does NOT make the fuel/ volts move like it should.

Some buds said to try and reset the computer. Not sure if I should try that or not.

This is what my asd/feels like fuel pump relay is doing, the aux fan is also coming on when the key is 'on'


So help me out guys! Any advice is much appreciated!

 

Bump... Anyone?

 

Try swapping that relay, but it does sound like you've got a melt/short somewhere in the wiring harness.

 

I have swapped it out. My dad has an '00 also and I tried it in his and it fired right up. Tried his in mine and it did the same thing

Some people said check coil ground. Does anyone know the location of it?

 

Yeah it's on the same side of the engine block, you'll see a point where a bunch of lugs converge on two studs.

 

Ok I've cleaned those already. So that wasn't it

 

Doesn't mean they're necessarily good. Corrosion can often cause issues up the cable under the insulation. Got a multimeter? Measure resistance between ground points and the negative battery post.

 

True. I'll have to test them.