Where to purchase GEM module/ECM

You should be able to find a good used one yet at any salvage yard. Beginning a few model years later, it became necessary to have modules programmed to your car's VIN, and often that can only be done at the dealership.

If you do not want to go to the salvage yard, you can probably find a good used one on eBay or car-part. Com for a fair price.

Programming of modules is a trick designed by GM to force you to go back to the dealer. Other manufacturers copied that in later years to squeeze more money out of their customers. It is the main reason I drive older cars. That should not apply to your car.

The Sable uses a module that does need to be programmed to the vehicle. That is because they used 3 different versions of that engine, plus different tire sizes, gear ratios, and shift points in the car. Plus the PATS system will need to be updated to make it start using the current keys. If you find one that matches the unit you have and uses the same engine/trans combination it might work but I wouldn't say it's a sure thing.

The procedures are common and many place other than the dealer can do programming as it's a required part of many repairs on all makes these days. Even things that sound like they don't require it will need to be programmed. Like adding fog lights and a trailer wiring harness to the wife's Dodge Journey. Change the main battery in a newer Corvette? You need to reset the battery monitor to match the CCA and voltage output of the installed battery so it will properly charge the new one.

This is a TSB on your car -

ISSUE
PCMs may need to be reprogrammed or replaced as part of a repair. Additional vehicle concerns may be caused if proper programming procedures are not followed.

ACTION
Use the following procedure to reprogram PCMs.

Verify repair after reprogramming.

SERVICE PROCEDURE

PRELIMINARY STEPS - Existing PCM

Reprogramming Or PCM Replacement
1. Connect a battery charger to vehicle.

2. Use WDS if available.

A. Make sure WDS is docked or attached to vehicle battery supply.

B. Verify WDS software is at the latest release level.

3. If there is a communication error, attempt to communicate with a different diagnostic scan tool, such as NGS, NGS+, VCM or another WDS.

NOTE IF COMMUNICATION STILL CANNOT BE ESTABLISHED, VOLTAGE DROP PCM POWERS, GROUNDS, AND CHECK VREF.

PCM REPLACEMENT - STANDARD
1. Open WDS vehicle session with original PCM installed in vehicle. If the original PCM is not able to communicate, to open a session, proceed to the Blank Path Programming procedure.

2. Install the new PCM.

NOTE IF WDS NEEDS TO BE USED ON A DIFFERENT VEHICLE WHILE THE NEW PCM IS BEING INSTALLED, PLACE THE VEHICLE SESSION ON "HOLD" FOR USE LATER.

3. Attempt to start the vehicle.

4. Run KOEO Self Test to check for diagnostic trouble codes (DTCs) in PCM.

5. Check for DTC P0602/P0605/P1639.

A. If DTC P0602/P0605/P1639 is present then Programmable Module Installation (PMI) procedure must be performed. Use the WDS session opened at Step 1.

B. If DTC P0602/P0605/P1639 is not present, then verify Programmable Parameters are properly set such as tire size, axle ratio, etc.

6. Check for DTC B2900.

A. If DTC B2900 is present, perform PMI on the ABS module. Do Not replace ABS module for this procedure when directed. You may be prompted to enter the 9 lines of PCM As-Built data during this procedure.

B. If DTC B2900 is not present proceed to Step 7.

7. Diagnose all other DTCs following normal diagnostic procedures.

BLANK PATH PROGRAMMING - Existing PCM Reprogramming Or PCM Replacement

Perform this procedure prior to PCM replacement if a vehicle comes in with a PCM that will not communicate, or if steps earlier in this TSB directed you to this procedure.
1. Verify powers and grounds to PCM by loading and voltage drop testing circuits.

2. Follow Pin Point Tests to verify network integrity.

NOTE IGNITION MUST REMAIN IN THE OFF POSITION UNTIL PERFORMING STEP 8. DO NOT TURN THE KEY ON WHEN WDS IS INITIALLY CONNECTED TO THE DLC.

3. Connect WDS to vehicle.

4. Select "16 pin", select "All others, except those below", press TICK.

5. Screen shows installation of cable, press TICK.

6. Screen shows to turn ignition ON. DO NOT TURN IGNITION ON. Press TICK.

7. Screen shows progress bar, then screen tells you "No communication can be established with the PCM" and asks you if you want to retry? Select "NO". With the ignition key still OFF, press TICK.

8. Screen shows to turn ignition ON. Turn ignition on, press TICK.

9. Screen shows "The PCM installed to this vehicle is blank". You will be prompted to select VIN from a list of previous sessions. Press TICK.

10. When previous sessions are shown select "None of the above".

11. Screen shows 'To enable WDS to reprogram the PCM with the correct calibration", enter one of the following: Vehicle Calibration # (7 digits), Tear Tag # (4 digits), or PCM part #, press TICK.

12. Highlight the box next to the selection chosen, and enter ONLY ONE of the selections listed above. Press TICK.

13. Follow and answer correctly all remaining screens.

14. Once PCM is reprogrammed communication should be reestablished and PATS system can be reset (if necessary) as per Section 419-01 of the Workshop Manual.