Computer swap

[JohnCougarMan]

Hey Guys!

My 1995 Bick Park Avenue Ultra (3.8 SC) is wacky. I got it free, ran great, but the transmission was out of it. So, I swapped a cheap one in from a junk yard... anyway. Like I said.. it ran great, started it up often between the time I got it and the time I put the tranny in, for the purpose of preventing any engine damage from sitting.. so, now its wacky. It overheats if it sits at idle, and the water temperature gauge is wrong (and.. still wrong, but is way off on a computer scanner... even off of the gauge) It read -99 degrees Farenheit for the transmission on the computer, and it won't go into high gear. On top of that, even with three new alternators, it wil not charge. The alternator is getting a charge, and all the wiring is hot, but it's like it won't accept the charge. When the battery gets low... the whole thing is screwy, idiot lights flash (all of them.. just flash), oh.. and no matter what the door buzzer dings constantly (and faster than normal.. if the door was open or keys in the ignition)

So question: What is it? to me it sounds like the computer.. and if so, with a 1991 Buick PA Ultra SC computer be compatible? Again... if so.. anyone know of a tuturial or just some advice on swapping the computer?

Thanks,
John

[HotZ28]

Do you know if your car is OBDl, or OBDII? 1995 was the transition year from one to the other. Look at the sticker on the radiator shroud and it will tell you if it is OBDII compatible. Also, the OBDII PCM is located in the engine compartment, instead of the passenger compartment.


Do you know if the transmission came from the same model year, if not, you may have a wiring problem at the terminal connector? If the car is OBDII, a new PCM would require flashing to the specific VIN & model. If it is OBDI, the prom will need to be removed from the existing unit and installed into the new PCM/ECM.

BTW, the 1991 model was OBDI and had a prom/chip, not the same as OBDII!

[JohnCougarMan]

Okay.. I believe it is ODBII.. the tranny was put in by a friend of mine, hes a very competent mechanic, so I don't think there was an installation issue.. but as for wiring.. it was getting a QDM failure (forgot to mention it). It supposedly did come fom a 1995 Park Avenue... but I suppose the junkyard could be wrong. I don't remeber the actual transmission Designation, but it was the same as the one I pulled off.

So if I am understanding you right... assuming the tranny is right, the wiring is right, etc... the problem could be fixed by re-flashing the computer? If so.. how much would a mechanic charge to flash it? Could I rent a programmer?

Thanks,
John

[HotZ28]

As you will see in the pic below, the 94-95 has several different model 4T60E transmissions installed. (Models CMW, PHW & PCW) Check your wiring harness and trans pin-out for compatibility. QDM fault may be an indication of incompatibility! Also, the PCM may need to be replaced and flashed, not just reflashing the existing one. You can not “rent" a programmer to reflash the PCM, it would need to be flashed at a dealer or by someone that has the vehicle specific program for your VIN.

[JohnCougarMan]

Alright, so Im gonna go out with that diagram and check for compatibility. Lets assume it is NOT compatible.. am I basically up a creek without a paddle? Or is there something I can do (other than spending another 13 hours replacing a tranny) to fix this car? And if it is compatible.. I can just replace and re-flash?

And yeah.. T460E.. that's what I was thinking of. I was worried, because my 1991 has a T460HD, that it was wrong (HD=Heavy Duty I assumed for the SC engine) But I will look!

Thanks!
John

(sorry... im mechanically slow on these cars.. the electronics on cougars are a lot easier!)