Failed visual inspection

Cherokee coil failed visual inspection
I have one of the bluetooth OBD readers that I left connected to the port.
My ECU has burned and the coiled melted. I would advise not to leave a bluetooth OBD connected for any longer than needed.
Does anyone have advice or experience with leaving the device connected? I know it has to draw a small current but not sure that would be a problem.
I have ordered a replacement ECU that is preprogramed.

 

That did not happen because you left your BT scanner in. Any "excessive" draw from it would have blown a fuse, not your ECU and coil. You have much more significant short somewhere but I can't begin to guess. I've never seen an XJ coil like that.

What year is it?

 

i have seen 4.0 coils like that but its just from corrosion from salt and water. and you can see all the rust coming out of it in the cracks of the cover

 

That did not happen quickly. That took awhile.

I've seen a GM HEI coil look very similar even being under the plastic cover. It happens

 

And to nail that coffin in the other direction, I've had a BT OBD unit in my Subaru for about 5 years without taking it out. Zero problems.

 

Yeah, that's just a really oil coil. There's nothing unusual about that. Just replace it and carry on.


My OBD unit lives in my Cherokee, too. No problem, and no reason to believe it could ever be a problem.

 

Friend of mine's 98 had that same crappy rusted coil...could not get a good spark off it...got a new advance autoparts model for 35 or 40 bucks with the on line discount started up like a champ....the iron coil layers are not water or airtight and when it rusts from the inside it cracks the plastic...common..get the correct year...older models have round pins in the connector...newer years have flat square pins

 

Look at the brand name on that coil. I'm curious.

 

Just curious, how did you determine that your ECU is burned up?

 

i leave my obd reader in also, with no problem. i forgot to mention that earlier

 

5 different scanners won't connect.
the onboard OBD doesn't light up or work with the 3 times key on procedure.
only the oil light by the speedometer lights.
the check engine light or nothing on that left hand row comes on.
the fuel pump continues to run as long as the key is on and it usually cuts in 1 or 2 seconds.
i could still be wrong. could be a harness wiring.
thanks for making me think more about it

 

It's rarely a bad ECU. The fuel pump initially running on key-on and stopping after a few seconds of not seeing the engine crank is normal. That's controlled by the ECU, so I don't think it's completely dead (or likely not bad at all).

You might have something else more common going on. Blown fuse, damaged wiring, a bad ignition switch, etc.

 

Bad ground also a possibility.

 

I live by these words now.

 

I feel like when you sign up to this forum, you should have to tick a checkbox confirming that you've checked your grounds.

Even if you're joining for a mechanical fault or general questions. I've got death wobble - check your grounds first