trans codes

[joeb]

I am looking at a 97 STS. it will not stay in OD. the owner says it has 2 codes. PC1626,TC0037. these are the only 2 codes. I did not find any info after doing a search. any ideas?

[PAUL T]

I am looking at a 97 STS. it will not stay in OD. the owner says it has 2 codes. PC1626,TC0037. these are the only 2 codes. I did not find any info after doing a search. any ideas?

P1626 - Theft deterrent system Fuel enable circuit

TC0037 - is a traction control code

I would say you are looking at replacing the shift solenoids without more information.

[Cadillac Jim]

Those codes are incomplete and don't address the transmission problem. The code that is thrown when the transmission won't stay in overdrive is usually P0741 but may be others, usually of the form P074n. Here's what I turn up from the code numbers you give:

P1626 Theft Deterrent Fuel Enable Signal Not Received

B0037 AUX switch closed/shorted to ground (an air bag code)

P0037 Heated Oxygen Sensor (HO2S) Heater Circuit Low Voltage Bank 1 Sensor 2

These codes seem to tell us that the car has been started with a cheap duplicate key and there is a bit of a network problem, an air bag signal is shorted, and you may have a bad oxygen sensor. Codes like this are common at used car dealers after washing a car but are a bit odd because, if they knew to clear the codes, they should know to clear them after the car dries out. If it's not staying in overdrive and there aren't any transmission codes, then the codes have been cleared and it hasn't been driven through an OBD II driving cycle. So, the codes you give, together with the complaint that the car is dropping out of overdrive, are more than a little bit strange and disconcerting.

If you are really interested in the car, the first thing I would do at this point is to run the VIN of the car through CarFAX. If it looks good there, you can proceed; if not, you can save yourself time and energy. Then, I suggest that you pull the codes yourself (key on, engine not running). Most codes will be followed by the word "HISTORY" on the DIC. If any are followed by the word "CURRENT" then they were thrown when you turned on the key -- be sure and make a note of any codes that are current.

The codes given by the DIC when you pull them from the console (here's how) are in the form

XXX Xnnnn

where XXX tells which module is throwing the code (PCM, PZM, etc.), X is a prefix letter and nnnn is four numerical digits. The prefix letter is very important and will be one of B (body), C (chassis), P (powertrain) or U (network). The module is usually not important but sometimes more than one module can throw the same network code, so if you get a Unnnn code, write down the three-character module acronym.

Then, start the car and take it on a test drive. Drive through the GM OBD II driving cycle (click here for a post on this board that has this driving cycle as a text file attachment). After you are done, then, with the key still on and the engine still idling, pull the codes again and make a note of all the codes and whether any are current. Post them here and we can probably tell you exactly what you are looking at, and certainly tell you pretty much all the problems must be solved to have a perfectly trouble-free car.

Alternatively, you can have a good mechanic check over the car. There are services in many areas that offer this specific service. Even if I had a mechanic or inspection service examine the car, I would run the codes myself just to observe the seller – watch for an exposed epiglottis and whites of the eyes visible completely around the iris, facial tics, a mottled complexion, sneezing fits, insistent distracting conversation, a total loss of interest in selling you the car, etc. – or just a Jack Benny detached demeanor; all are warning signs.

Please do not think that I am prejudiced against used car salesmen; after all, no one is born a used car salesman.

[joeb]

I have a 96 STS and have been coming to this site for 2-3 yrs now and am fairly familar with the myriad codes a caddy might throw. My son wants to buy a caddy now. I guess we spoiled him by letting him drive the caddy. the owner was asking 2300 at first but this week he raised the price to 3k. must be getting offers. the car is green which I do not like. my son really wants a white car. he says he might take a partial trade since he does not have another car. he said he does not feel like fixing the car. I thought he might have a TC0073 code and made a typo but he said it is 0037. we are also looking at a 98 for more money. newer body style.

[Cadillac Jim]

You didn't say what year and model Cadillac this indivusual was offering for $3K. Check CarFAX first. If he was originally asking $2.3K I would tread carefully, and get that $700 back in closing the deal. Go to the KBB web site and evaulate the fair price for the car before you start serious price negotiation. Also, I would run the codes myself, before and after a test drive. Watch out for the standard issues like head gasket leakage or long neglect of the coolant, transmission codes and peculiarities, etc.