03/04 engine/trans swap into 01

[notchstang92]

I did this swap years ago. Keep the 01 harness. Extend the IAT wires to the lower intake where the IAT2 is located on the eaton cars. The alternator wiring isn't hard either. I bought the pigtail for the alternator and the IAT2 and wired them in. I also ran the 03 tank and it bolted right in. I don't have the alternator wiring diagram, but I did have the ones that show how to run the IAT2 sensor off the IAT1 wiring. Hope these help.

 

[Slowings]

The harnesses are different enough that you can't do what you're wanting to do.

IAT=inlet air temp. The 03/04 has a sensor for that on the lower manifold. You want to tap into that one. The 01 sensor is in the intake pipe by the MAF. So you'll need to extend the wires.

IAC= idle air control. Silver canister by the throttle body.

I'm sure you can see the issue with the alternator wiring.

Sorry to come back to this, so can I or can I not use the 03/04 alternator/starter harness with the 99/01 engine harness? So I know what I gotta change with the engine harness now, only thing I’m hung up on now is this alternator/starter harness. The sensors from my 99/01 harness aren’t in the same spot, and of course the alternator placement haha. I would love if I could just use my 03/04 alt harness and get it plugged up and go for a start this week once I change up the engine harness. Got the gas tank swapped today.

Time is my biggest issue, never enough time to get it done aside from a few hours here and there

 

[Slowings]

I did this swap years ago. Keep the 01 harness. Extend the IAT wires to the lower intake where the IAT2 is located on the eaton cars. The alternator wiring isn't hard either. I bought the pigtail for the alternator and the IAT2 and wired them in. I also ran the 03 tank and it bolted right in. I don't have the alternator wiring diagram, but I did have the ones that show how to run the IAT2 sensor off the IAT1 wiring. Hope these help.

Oh wow! I didn’t even see this reply when I just posted another comment haha. But sweet. I just did the tank and saw that was plug and play. So pretty much I can just cut and splice the alternator harness and replace the one from the 01 harness?

 

[RX1Cobra]

Yes, that's it. Make sure you wire it correctly though. I don't remember exactly what it is but theres three wires and they're different colors than the 03 plug. In the 01 harness one went to the gauge, one just ended in the harness (white maybe?) and one controlled the how much power the alternator produces. This is all going by memory so verify before you do anything.

It's been a while and I don't recall how they should be.