91 tranny trouble

[crosscomp]

My trouble started when the throttle position sensor went bad(replaced that)
then the tranny wouldn't shift into 4th and it felt as if it was stuck in 2nd or third( sluggish on takeoffs ), changed filter and fluid (thinking maybe filter plugged) no change. then I changed the vacume modulator(still no change),
Could the valve behind the modulator be stuck or clogged. Is the shift points controlled by the computer and if so how do I tell if the ECM has gone south?
If the tranny has died how hard is it to change?


Sean

 

[Ghost C]

To answer your second question, yes, the shift points are controlled by the Powertrain Control Module (ECU/ECM - This car has a PCM). To check your computer for codes, hold down the OFF and WARMER buttons on the climate control center. A list of trouble codes, if any are present, will be displayed on the fuel center screen, write the codes down and post them on here and I can tell you what they are. A .7.0 means the test is completed, press auto to shut diagnostic mode off.

As for changing a transmission, it's not easy, but it's not difficult if you have some mechanical experience with the car. I would suggest buying the Haynes Repair Manual for the 86-93 DeVille, and buying a Factory Service Manual for your year DeVille if you can find one.

 

[crosscomp]

The only code I get is E40(power steering pressure switch). I've got the Haynes Manual and have a shop manual on order. Where is the PCM?
Sean

 

[Ghost C]

If I remember correctly it's underneath of the glovebox, below the control box for the power door/trunk system. I would not go tampering around with it unless you are 100% sure of what you're doing, as you could do more damage than you fix.

 

[crosscomp]

Thank you,I wonder if there is a fuse blown in the fuses under there.
Sean