Can anyone who knows from experience tell me what year PCM's will work with a 94 Trans Am? I am trying to resolve a transmission problem and have been told by a transmission shop that the problem MIGHT be the PCM and not the transmission. I have already swapped in another transmission (broke my finger in the process) and it does exactly the same thing that the old transmission was doing. I've checked the wiring and its all intact. I just need to know if I am limited to a 94-95 PCM or if I can use the later 96+PCM without problems.

 

Not sure if it can be reflashed, but I think you'll have a problem using a 95 PCM unless you have a 95 4L60E as well. 94 doesn't use PWM for the converter lockup, whereas the 95 does. What problem are you having with the trans?

 

94 and 95 f-body PCMs (OBD-I) are the same, only the programming is different. 96 and later are are OBD-II (doesn't mean you could not use one if you wanted to, though).

 

I'll try to clear up the issue:

The car is a 94 T/A GT A4 (4L60E). I've paid for at least 3 "Hi-Po" rebuilds of the original tranny that were worthless. About 4 years ago after the original tranny failed YET AGAIN I found a used 95' 4L60E that had been "built" for racing by a shop in Denton on Craigslist for $300 bucks. I figured it couldn't be any worse than what I had in the car. Turns out that 95' craigslist tranny was the best tranny I've ever had in the car. Last summer I drove the car one night and had ZERO issues with the tranny (shifting perfectly) and I parked it that night. The next day when I got in and started to drive it I noticed immediately that the tranny was slamming into 3rd gear violently. I came to a stop and then noticed that the tranny would no longer drop into 1st gear. I drove it up to highway speed and although the converter would lock in third at 45mph..overdrive (4th will not engage). Stopped and turned off the car then started back up and PRESTO..1st gear is back until it shifts to 2nd and then it goes into the same mode. ALSO...just as a test...I drove the car up to highway speed (about 75 or so in 3rd)...shifted to neutral and killed the engine (thus resetting the PCM)..then fired it back up while coasting and put it in "D"..and it went into 4th and locked the converter like it should. I assumed the tranny was shot so I found ANOTHER used 4L60e and swapped it out....and to my horror it does the EXACT same thing. Pissed off I went to a local 4L60E specialist and he plugged up a scantool and immediately found a code for the 2-3 downshift solenoid which he says is placing the car in limp mode. He told me that he had never seen THAT solenoid go out...but especially not in 2 transmissions in a row. He told me to check the wiring and look for a broken PCM ground...OR that he wouldn't be surprised to see the PCM as the culprit. It is a 16 year old PCM afterall. I just need to find a good PCM to plug in to the car to see if it restores the transmission operation...in which case THEN I will buy a new (or used) PCM. I suspect the A/C failure could possibly be the PCM also because when I bypass the compressor relay the thing blows cold air..and I know the PCM controls that relay as well. So I just need to know what cars I can borrow a PCM from that will work with my 94 T/A.

 

Wow, I wasn't expecting all that! As bad as the 4L60E can be, I definitely agree that you have an electrical problem of some sort. I find it hard to believe that many transmissions could just be instantly bad. As far as your checking with another PCM, see Shoebox's post above. Unfortunately a PCM is one of very few things I don't have a spare for, or else I'd loan you one.

 

Too bad you are in texas. I have an extra ECM out of a '94 LT1 Roadmaster I could let ya use...