tilly

Hello,

I am helping a buddy of mine do a PI swap into his 98' Mustang.

I am trying to figure out the wirinng to the PCM. This car has been hacked up BIG TIME. Originally this car was 1998 Mustang GT. It then saw some turbo motor in it and then a 2003 Cobra motor.

Those motors are long gone and you can tell by the wiring harness.

Now my buddy got a motor from a 1999 Mustang GT, it has the coil on plug ignition system, and I know at least the wiring harness has changed between 98 and 99. Now I dont know what wiring harness this car has. I know the engine hanress for this pullout is for the 1999 Mustang GT, now I do not know if they put a 03 Cobra harness to get the cobra motor to work or if they modified the 98 harness to work.

I am sorry if this is not clear, Can some one tell me the differences between a 1998 Mustang GT, 1999 Mustang GT and a 2003 Mustang Cobra wirning harnesses. Are the chassis harness the same, are the PCM layout the same. I have a Haynes manual and it aint helping too much.

Thank
Tilly

RuffCat

You must have a 99+ engine harness. The harness from the firewall to the ECU needs to be 99+ due to the COP's. You must also use an ECU that has been programmed for a 99+. You also cannot just buy a 99+ ecu and expect it to work because of the PATS theft system built in. Your ecu right now whatever you have will be fine. You just need to take it to a dealership and have them reprogram it for a 99GT. I called my local place and they said the charge would be 1 hour of labor. $95

tilly

I have the engien harness from a 99 and I have the 99 ECU. So I just need the 99 Harness from the engine harness to the ECM.

Correct?