CaDreamr,
If you have a Cadillac/GM that is 1995 or earlier follow the instructions I gave in my post above to enter diagnostic mode. These vehicles (Cadillac, Chevrolet, Buick, Oldsmobile, Pontiac, Saturn) are equipped with the On-Board Diagnostics I (OBD I) system. All GM cars and light trucks built and sold in the United States after January 1, 1996 were required to be OBD II equipped. If your vehicle is a 1996 or later model than it will be OBD II equipped.
Reading OBD II Codes
"A cable is plugged into the OBD-II J1962 connector and the other end is connected to a scan tool. A hand-held scan tool is usually limited to one OBD-II system type - there are three basic OBD-II protocols in use, each with minor variations on the communication pattern between the on-board diagnostic computer and the scan tool. In general, Chrysler products and all European and most Asian imports use ISO 9141 circuitry. GM cars and light trucks use SAE J1850 VPW (Variable Pulse Width Modulation), and Fords use SAE J1850 PWM (Pulse Width Modulation) for communication."
See below link for OBD II Codes:
http://myweb.accessus.net/~090/dtcobd2.html
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TJAXFF,
I've been dealing with the P039 code for about 60,000 miles and the transmission is still going. My symptoms include lazy shifting, weak acceleration at times, slipping transaxle, lower mpg, and, of course, the consistent SERVICE ENGINE SOON light. If I replace the transaxle, which may be in the very near future, I will buy a performance transaxle with a limited slip differential. The limited slip will cause both front wheels to spin thereby improving acceleration and derivability.
http://www.phantomgrip.com/.
The P039 code is set when the difference between the engine speed and transaxle turbine speed of 48rpms (VIN #9 vehicles having a final drive gear ratio of 3.71 only) or greater is detected. If your vehicle is, for example, a 94 Eldorado Touring Coup, than your vehicle's VIN # will contain a "Y" and your final gear ratio (4th gear) will be 3.11. On these vehicles acceptable slip speed is based on engine torque delivered for 4.5 seconds. The PCM analyzes both and will set only if the torque applied/slip speed exceed acceptable limits. Once the code is set the torque converter is deactivated to prevent the transaxle from overheating.
1994 Cadillac Service Manual, p. 6E-A-140.
An intermittent code P039 setting may be caused by delayed TCC [Torque Converter Clutch] engagement (usually the first apply after a cold start) or by TCC slippage during high engine load conditions. Delayed TCC engagement can be checked using PCM Output Override PS01 (TCC Solenoid) to disengage and engage TCC and time how long it takes TCC to engage by watching PCM Data PD73 (Torque Converter Slip Speed). Delays of over 5 seconds may cause the code to set. TCC slippage during high load conditions can be determined by looking at code P039 Snapshot Data. High throttle angle (PD01), MAP (PD02), and engine coolant temperatures (PD04) may indicate a high load condition. Duplicating the high load conditions may cause the code setting conditions to occur.
1994 Cadillac Service Manual, p. 6E-A-140
