Was driving around yesterday after having been away for a few weeks, everything good felt good to not drive a company truck! Anyway driving along and the check engine light pops on and the jeep is misfiring and bogging down. I get home and start poking, threw the scanner on it and its P0202 Injector circuit cylinder 2. I test the injector it ohms correctly, but as I run it i get out my stethoscope and i can't hear that one fire. Every other one is tick tick tick but i get nothing from 2. Start prodding around and find that on the control wire from the pcm to the injector i have 4.8 volts. Every other control wire for every other injector is 13.? I go back to the PCM and back probe each wire for the injectors and same reading 4.8 on 2, 13.? on the other five. Okay so I grab the PCM out of the ladys jeep (98), fires up, sounds good, no check engine light! My question is whats the off chance that the computer just decided to fry the injector 2 control circuit? Or is there some other root cause that i make want to look at, going to grab one from the JY today and don't want to kill another one. Thanks four your input!

 

Additional Info, after swapping pcm, oil pressure gauge no longer works.

 

On Heeps, this is out of my realm, but doesn't the PCM provide a ground circuit to activate an injector?

 

It is my understating and looking through the diagrams that they all share the same ground, not an individual per injector. That being said I would think that if the ground went bad I would have a fault at every injector not just one of them?

 

The injectors, and most of the components controlled by the PCM are ground switched. I have seen a few XJ ECMs fry an injector driver for one cylinder.

 

So maybe I did get "lucky" and it was just that one circuit that got toasted. Still going to try and source a 99 pcm, but the 98 one is holding steady so far