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91 MJ 4.0L 5-speed owners...Please read


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I am looking to confirm something on your trucks. I'm installing complete 1991 HO 4.0L, AX-15 5-speed wiring in my '89 Comanche. For those of you with the 1991 4.0L, 5-speed combination can you take a peek at the PCM plug (driver inner fender). You don't need to unplug anything. There's a cap over the PCM plug that conseals the wiring. Unfasten the 2 clips that loosen that cap. If you are standing in front of your truck at the header panel/ front bumper it would be the top row of 10 wires closest to you. You won't have to dig at all to see there.

 

I believe the order should be (starting closest to the PCM plug mounting bolt) : NO WIRE (pin slot is capped), MEDIUM BLUE, BROWN (?), ORANGE, PURPLE/WHITE, BLACK/WHITE, BLACK/BLUE, RED, TAN/BLACK, GREEN/RED

 

I have a 1991 FSM and I looked at the starting diagram and believe it is incorrect a bit for the manual transmission, so I am looking to confirm off an actual vehicle. Thanks.

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I have a 90 configured this way but can't see what you are looking for. Is the 90 set up differently or am I being dense? Based on the day I have had I am expecting the latter. If the 90 and 91 should be similar tell me again what I am looking for and I will look again.

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Thanks for posting. I'd like to get another couple people to chime in to see if their 91 has the brown wire between the blue wire and orange wire.

 

For some reason my 91 MJ 4.0L 5-speed harness did not come with this wire over to the PCM -- and it does not look modified. My wire just goes straight from the starter relay to the starter. It wouldn't be an issue except I am not using the PCM the wiring harness was originally matched with. I live in CA, so I will be plugging the harness into a CA-emissions PCM versus the Federal PCM it came with.

 

I've got all my wiring out and am looking to get it right the first time. Thanks

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Thanks Dave - Your MJ is wired like mine at the PCM - that being without the brown starter wire to the starter relay. I know you live in CO, but out of curiousity, do you have a CA emissions MJ? It would say California on the emissions label located on the firewall.

 

Correy - I'm guessing based your location you've got a FEDERAL emissions vehicle?

 

Thanks again all.

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