For 1990-2009 cars

# Info - PCM Reprogramming

Subject: | Powertrain Control Module (PCM) Reprogramming (Do Not Reprogram Using The Same Download Files As Those Already Present In The Control Module)

Models: | 1990-2000 Passenger Cars and Trucks with Reprogramable PCM

It is strongly recommended to NOT reinstall the same software and/or calibration download file(s) into the powertrain control module as those that are already present in the PCM. There is no technical reason that the download files inside the PCM would ever become corrupted after the control module had previously been successfully programmed. A P0601 (Control Module Read Only Memory) Diagnostic Trouble Code would set in memory and the MIL would be illuminated if the controller memory became corrupted.

The Techline Information System 2000 (TIS 2000) PC, combined with vehicle information gained through the Tech 2, can determine when an attempt to reprogram a PCM using the same download files (as those already in the control module) is being requested. If this is attempted, the TIS 2000 PC currently displays the following message:

NOTICE: THE CALIBRATION SELECTED IS THE CURRENT CALIBRATION IN THE CONTROL MODULE. PROGRAMMING WITH THE SAME DOWNLOAD FILES IS NOT AN EFFECTIVE REPAIR. SELECT ( YES ) TO CONTINUE PROGRAMMING THE CONTROL MODULE, OR ( NO ) TO CANCEL.

Effective in the first quarter of 2000, the TIS 2000 PC will indicate:

Important: THE CALIBRATION SELECTED IS ALREADY THE CURRENT CALIBRATION IN THE CONTROL MODULE. REPROGRAMMING WITH THE SAME DOWNLOAD FILE IS NOT ALLOWED.

Certain learned values, such as: (but not limited to)

• | fuel trim (previously known as block learn memory),

• | IAC learned position in various park/neutral and air conditioning on/off combinations,

• | certain OBDII diagnostic thresholds,

• | automatic transmission shift adapts

will revert back to their unlearned starting point values after a reprogramming event occurs.

It is feasible that the engine or transmission might temporarily operate differently after a reprogramming event, until these values are re-learned. Relearning occurs while operating the vehicle through normal driving routines. If the same download files are simply reinstalled, any changes noticed in engine operation will likely disappear in a short amount of time and/or driving distance.

Reprogramming the control module with the same download files that already exist in the module will only accomplish a warranty claim for a non-effective repair, and a likely comeback.