dmk9561 Posted August 11, 2009 Report Share Posted August 11, 2009 My parents recently saw fit to bestow on me a 1995 SLS. It's been their baby for 10 years and I'm thrilled to have it. It has about 75,000 miles. As dad warned me, the SES light does come on sometimes. I put it in reader mode when it came on and got "P039 CURRENT" and "P044 HISTORY." I know that 44 means O2 sensors, and I don't doubt that a 75k car needs them. I'm going to change the spark plugs, too. The P039 is a TC clutch problem I've found is supposed to be helped in many cases by changing out a PROM chip in the PCM. This chip is always said to be about $45, but I've found it's become hard to come by and now costs $95 if you can find it. I'm going to change it. If that doesn't cure it, I know that I'm in for a bad one, so I must try that first. What I want to know is: where is this PCM located? How long will it probably take to change (is there a bunch of ridiculous stuff in the way like the rear plugs)? Has anyone else here done that and have any other things to mention? I love the car, BTW. I'll be changing the oil and front brakes this weekend, too. Between those things and the chip, it's two Michelins away from perfect. Link to comment Share on other sites More sharing options...
BodybyFisher Posted August 11, 2009 Report Share Posted August 11, 2009 Mileage has nothing to do with an O2 sensor going bad, excess fuel, silicone or just a failure can cause them to go bad also, forget the 75K your car is 14 years old. It will need many repairs due to its AGE alone. If you do a search, others have discussed changing the PROM chip. I doubt that a new chip will fix the TC clutch problem, there is a solenoid in the tranny that can go bad, you might be able to test it in an OBD1 system Pre-1995 - DTC codes OBD1 >> 1996 and newer - DTC codes OBD2 >> https://www.obd-codes.com/trouble_codes/gm/obd_codes.htm How to check for codes Caddyinfo How To Technical Archive >> http://www.caddyinfo.com/wordpress/cadillac-how-to-faq/ Cadillac History & Specifications Year by Year http://www.motorera.com/cadillac/index.htm Link to comment Share on other sites More sharing options...
dmk9561 Posted August 11, 2009 Author Report Share Posted August 11, 2009 Ok, but the conditions that cause my SES light perfectly mirror the ones mentioned in the TSB. I drove the car all weekend without seeing it, but it often pops up if the car climbs a lengthy hill against a high gear. It also seems that the PROM change eliminated the light most of the time for the people who knew to do it. The biggest problem was that it was almost like a secret. It's likely that many cars got an unneeded transmission rebuild over what could've been a cheap fix, only to have the light return as it was really due to incorrect programming. Link to comment Share on other sites More sharing options...
BodybyFisher Posted August 12, 2009 Report Share Posted August 12, 2009 Ok, but the conditions that cause my SES light perfectly mirror the ones mentioned in the TSB. I drove the car all weekend without seeing it, but it often pops up if the car climbs a lengthy hill against a high gear. It also seems that the PROM change eliminated the light most of the time for the people who knew to do it. The biggest problem was that it was almost like a secret. It's likely that many cars got an unneeded transmission rebuild over what could've been a cheap fix, only to have the light return as it was really due to incorrect programming. That maybe be true and if it is, terrific I dont have a 95, but your PCM is either under the dash on the passenger side or under the hood in the air stream of the intake.. Pre-1995 - DTC codes OBD1 >> 1996 and newer - DTC codes OBD2 >> https://www.obd-codes.com/trouble_codes/gm/obd_codes.htm How to check for codes Caddyinfo How To Technical Archive >> http://www.caddyinfo.com/wordpress/cadillac-how-to-faq/ Cadillac History & Specifications Year by Year http://www.motorera.com/cadillac/index.htm Link to comment Share on other sites More sharing options...
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