msedc Posted August 18, 2005 Report Share Posted August 18, 2005 Has anyone tried to replace a PCM in a 94 SLS? If so how? Link to comment Share on other sites More sharing options...
Oldgamer Posted August 18, 2005 Report Share Posted August 18, 2005 I replaced it. The best think is to have manual. It's not hard. PCM is located under glove box. You should drop the cover under glove box (I guess it has 3 or 5 screws). You will see silver color box on a floor with 3 big colored connectors. It's fixed with a bracket on a right side and a pin on left. Just in case before disconnecting a battery go into computer mode and write down PCM data PD99 (PCM PROM ID - Engine), PD97 (PCM PROM ID - Transaxle). Disconnect the battery before disconnecting PCM. Order PCM on-line. I found PCM from wrecked car for only $50. You MUST use your old PROM in a new PCM. To pull out PROM you should open window on a silver box and you will see a PROM in slot. To pull it out you should press clips. New PCM will came with PROM too, so you should pull it out too and insert old one. After connecting PCM and starting engine you may be need to make it relearn idle again. Good luck. Link to comment Share on other sites More sharing options...
navion Posted August 18, 2005 Report Share Posted August 18, 2005 I replaced it. The best think is to have manual. It's not hard. PCM is located under glove box. You should drop the cover under glove box (I guess it has 3 or 5 screws). You will see silver color box on a floor with 3 big colored connectors. It's fixed with a bracket on a right side and a pin on left. Just in case before disconnecting a battery go into computer mode and write down PCM data PD99 (PCM PROM ID - Engine), PD97 (PCM PROM ID - Transaxle). Disconnect the battery before disconnecting PCM. Order PCM on-line. I found PCM from wrecked car for only $50. You MUST use your old PROM in a new PCM. To pull out PROM you should open window on a silver box and you will see a PROM in slot. To pull it out you should press clips. New PCM will came with PROM too, so you should pull it out too and insert old one. After connecting PCM and starting engine you may be need to make it relearn idle again. Good luck. What would happen if you did not change the PROM's out & used the one in the replacement PCM? Britt Britt Link to comment Share on other sites More sharing options...
Oldgamer Posted August 18, 2005 Report Share Posted August 18, 2005 As manual says you always should change PCM OR PROM, never both, depends what is a cause of trouble. I believe that PROM stores some settings and ajustments for THIS particular vericle. In many cases it will be still fine with other PROM, though. Link to comment Share on other sites More sharing options...
32v_dohc Posted August 19, 2005 Report Share Posted August 19, 2005 Actually the computer for a 95 deville w northstar is the same as the computer for the 93 STS. The PROMs are different. This is the reason you keep the PROM with the car. Also the computer does store learned information but not on the PROM. It stores it on the EEPROM which is part of the processor. HTH John Link to comment Share on other sites More sharing options...
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