97+ Swap Wiring Questions

[Pseudosport]

I’m planning on swapping a 1999 dash, cluster, and harness into my Comanche and have a few questions.

 

1. I have the entire uncut interior harness from the 99 but not the engine harness. Can I use any engine harness from 1997-2001?
2. My truck currently has a manual transmission. If I use the harness from an automatic XJ will I have any problems with the computer throwing codes or do I just use a computer from a manual with any harness?
3. Can I use my stock fuel tank and pump till I find a Dakota tank? I’m ok with the dash gauge not working for now.

 

 

I realize I’ll need to splice a bunch of wires for interior lights, fuel pump, NSS, etc. I just want to make sure I start with the correct harness. I’d like to find the engine harness from another 1999 but if any work that just makes my search easier.

 

[Akula69]

Alexia had it right - I was unaware of the difference between the 1999 and the 200-01 harnesses

[Alexia]

1.) 1999 engine harness is 1999 only. A 2000 to 2001 engine harness will work with a 1999 interior harness, but you will need a 2000+ PCM to control the coil pack rail since 1999 is still a distributor ignition. 1999+ wiring harnesses are all fairly standardized for optional features, but specific about certain ones such as Federal/California emissions.

 

2.) Yes, just use a manual transmission PCM. Of course there will be some unused connectors. I believe you may have to do a couple items such as wiring in the neutral safety switch.

 

3.) If you mean a stock MJ fuel pump, absolutely not. It does not put out the required 49 PSI for the 1997+ fuel system.

[Pseudosport]

1. Forgot about the coil packs after 99. That would make things a little different.

 

2. I'm ok with the extra connectors. That would at least give me the option of swaping in an automatic later on. (bad knees but I like the manual)

 

3. Hmm, I could crush the regulator to reach 49 PSI. That would at lease let me test everything and move the Jeep around the yard if needed.

[Alexia]

3. Hmm, I could crush the regulator to reach 49 PSI. That would at lease let me test everything and move the Jeep around the yard if needed.

The MJ fuel system is a constant circulating system with the pressure regulator at the rail. The fuel rail for the 1997+ is returnless with the regulator built into the pump. The MJ fuel pump would simply continue to pressurize the system until it blows a hose off.

[Pseudosport]

I'd be using an older fuel rail with the built in regulator and return line. It's not the best idea but its something I could make work in a few minutes with some spare parts. I hope to gether all the stuff needed for the Dakota swap since that looks like my best option but I like having a backup plan.