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2003 Trans with a 1998 PCM in an 88 Fiero Swap!

3800Fiero

New member
HELP!

Hi guys, hoping someone on here has a custom tuning phd!

I put a 3800 supercharged swap from a 1998 Grand Prix in my 88 Fiero. I took a 2003 4t65e from a Grand Prix GT in it (lower miles). Well, the pcm programmer had me use a 1998 PCM to program but transferred to 2003 adapts and shift points to the 98 pcm. Well my transmission will not shift out of 2nd gear and I am getting the TCC P0742 code. The wiring harness is pinned to a 1998 Grand Prix. I added the range selector on the top of the trans from the 1998 trans to the 2003 trans. When I hook up my Modis it indicates the solenoid 1-2 is off and 2-3 is on with the key on and when started both are on. 2-3 solenoid never turns off even under hard load road test. The Modis also shows a "TFP SW???" - Transmission fluid pressure manual valve position switch - engine off in park. When I start it, it then jumps around - stating its "reverse" "park" "neutral" etc. I am wondering if we need to program a 2003 PCM instead of a 1998. Any advice would be greatly appreciated, wiring, computer, whatever you think could be the cause. Thank you.
 


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