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Jared D
Jared D, ASE Certified Technician
Category: Jeep
Satisfied Customers: 1334
Experience:  Shop Supervisor at County Fleet
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I have a 1995 Jeep Grand Cherokee it has a misfire on

Customer Question

Hi,
I have a 1995 Jeep Grand Cherokee it has a misfire on cylinder #2 & #4 i checked it and the fuel injectors are not opening, I've replaced the injectors and swapped them to different locations after changing them, it seems that there is no signal going to the injectors, I've inspected the wiring a few inches back on each injector and did not see any breaks, should i replace the ECM?
Submitted: 1 year ago.
Category: Jeep
Expert:  Jared D replied 1 year ago.

I hate to say it, but on a 1995 that's pretty much the best bet. Without the ODBII capability there isn't much else you can test. I can try to find a wiring diagram so you can test the injector leads at the PCM side if you would like to attempt it. That would rule out a break in the injector wiring and help diagnose the PCM.

Expert:  Jared D replied 1 year ago.

Here is the jeep PCM connector. You can see the injector drivers on the pin-out table.

Customer: replied 1 year ago.
Ok thanks, ***** ***** this out if everything checks out ok with the wiring ill have to order a PCM. Ill keep you posted
Expert:  Jared D replied 1 year ago.

Sounds good.

Customer: replied 1 year ago.
I just wanted to follow up with you I ordered a used PCM when installed it and turned the key on it immediately burnt up, I have ordered another one and I will check the harness more thoroughly before installing the next one.
I'll keep you updated on my progress
Expert:  Jared D replied 1 year ago.

Yeah, something is shorted. Check towards the back of the fuel rail bear the firewall. I have seen wires rub through back there and short out.

1. Check for a short to ground for the ignition coil.

2. Check for a short to ground in the fuel injector feeds.

3. Check for short to ground to the alternator, or a short in the alternator field.

Customer: replied 1 year ago.
I received my new pcm today and I'm attempting to trace out wiring but the diagram you sent might be the wrong one because it says pin 13 is injector 4 but pin 13 is empty.
Customer: replied 1 year ago.
I figured out the pin locations the pic looks backwards I'll get back to you in a few with my findings
Expert:  Jared D replied 1 year ago.

Oh, good. I was looking everywhere for a different diagram and couldn't find anything. Let me know how it goes.

Customer: replied 1 year ago.
Ok I checked continuity from ground to each pin for the injectors and I don't have continuity so I don't think there's a short, and I have continuity from each injector plug to its pin on the pcm connector, so there don't seem to be any breaks in the wires, however I don't know how to check the second wire for each injector do you have any recommendations before I put in the next pcm I don't want to burn up another one
Expert:  Jared D replied 1 year ago.

Any way you can get a hold of a noid light? You can plug a noid light into the injector's connector and see if it will light while cranking.

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