So, long story short, I'm getting no power from the PCM itself to fuel injector 4 (NOT the wiring that all checked out fine, the injector is fine its brand new actually, blah blah). I am getting a code that says "Fuel injector 4 open circuit" (P0204). I replaced the PCM for the first time, with one with exact matching part numbers and my jeep ran fine for a couple days, and now this different PCM is also not giving power to the same fuel injector. A friend of mine gave me a PCM out of their '98 XJ, all the same options, and I was curious if this would work in my '96 XJ? The part numbers are a bit different.. are any PCMs in XJs interchangeable with the '96? What would happen if I plugged this '98 PCM into my '96?

 

I would sure ohm out that injector. I think the spec is 12 ohms - hopefully someone else knows for sure.

 

How did you check the wiring?

 

Agreed.

An injector with very low resistance (impedance) will smoke the driver in the PCM for that injector. It is 12 Ohms at room temp.

 

I think the '96 PCM is a stand alone PCM and won't interchange.

The '98 PCM won't work. It's designed to interface with a '98 TCM, which is designed to interface with a new transmission electronic control system (new Input and Output Speed Sensors).

 

I've had two different, amazing shops look at it after my dad and I tested the injectors, they all tested fine. All the injectors except for #4 is getting power. I unplugged the connection to the pcm, figured out which wire it was, and the wiring from the pcm to that individual injector is fine. I tried testing the power from the pcm itself to that individual injector and there is no power.

Thanks for letting me know about the pcms.. that was my question. I will find one out of a '96.

 

Are you not showing power or ground to the injector? There should be a constant power to the injector, the driver is ground side. How did you check the wiring? Did you do a continuity test? Try unplugging the PCM and applying power to the hot side make sure your voltage stays where it should, resistance can make it show continuity but then kill the juice running through it

 

When you say the #4 injector is not getting "power" and there is no "power" from the PCM to the injector, are you saying the injector is not getting 12 volts DC or are you saying that the injector is not getting the ground circuit from the PCM injector driver?

 

I am working on a 96 myself and was told yesterday by junkyard 96 is stand alone ecm so 98 wont work