Restore Peak Performance to Your GM Vehicle
Is your 2003-2004 Buick Regal, or another compatible GM vehicle, suffering from frustrating issues like a persistent check engine light, poor fuel economy, or erratic shifting? These are classic signs of a failing Powertrain Control Module (PCM), the electronic brain of your engine and transmission. A faulty PCM can make your car unreliable and frustrating to drive. This replacement Powertrain Control Module, service part number 89017735, is the definitive solution to restore your vehicle’s original performance and reliability.
We take the guesswork and hassle out of the repair. Unlike a generic module from a salvage yard, this unit is professionally programmed to your car’s specific Vehicle Identification Number (VIN). We install the latest GM-certified software updates, which often correct factory flaws and improve drivability. This means you get a component that is ready to install right out of the box, with no need for an expensive trip to the dealership for programming.
From the Diagnostic Bay: The Intermittent No-Start
I remember a 2003 Buick LeSabre with the 3.8L engine that came into my shop on a tow truck. The owner said it would randomly refuse to start, but after sitting for an hour, it would fire right up. There were no consistent trouble codes, just a history of random communication errors. We checked the battery, grounds, and ignition system—all perfect. On a hunch, I gently tapped the PCM with a screwdriver handle while my apprentice cranked the engine. It started immediately. The culprit was internal solder joint failure on the PCM board, a common issue on these units after years of heat cycles. Replacing it with a quality, pre-programmed 2003-2004 Regal PCM like this one solved the problem for good.
Is Your Vehicle Showing These Symptoms?
- ✔ Unexplained Check Engine Light (CEL) illumination.
- ✔ Stalling, stumbling, or hesitation during acceleration.
- ✔ Harsh or erratic automatic transmission shifting.
- ✔ A noticeable decrease in fuel mileage.
- ✔ The engine cranks but refuses to start (intermittent no-start).
- ✔ Failed emissions testing.
- ✔ Stored diagnostic trouble codes (DTCs) such as P0601, P0602, or P0606, indicating an internal module fault.
A Straightforward Guide to Installation
Installing your new 2003-2004 Regal PCM is a job most DIY mechanics can handle in under an hour with basic hand tools. This pre-programmed module eliminates the most complicated step, making it a true plug-and-play repair.
- Safety First: Disconnect the negative terminal from your vehicle’s battery and secure it away from the post to prevent accidental reconnection.
- Locate the PCM: On most of these GM models, the PCM is located inside the air filter box housing in the left (driver’s side) of the engine compartment.
- Access the Module: You will need to unclip and remove the top of the air filter box to gain access to the PCM and its wiring harnesses.
- Disconnect the Harnesses: Carefully release the locking tabs and disconnect the electrical connectors from the old PCM. Inspect the connectors for any corrosion or damage.
- Remove the Old PCM: Unbolt or unclip the old module from its mounting bracket and remove it from the vehicle.
- Install the New PCM: Mount your new, pre-programmed PCM into the bracket, ensuring it is secure.
- Reconnect Everything: Firmly plug the wiring harnesses into the new module until they click into place. Reassemble the air filter box.
- Final Step: Reconnect the negative battery terminal. Your vehicle is now ready to start. In some cases, a security relearn procedure may be necessary, which can typically be done without special tools.
Verified Vehicle Compatibility
This module is a direct-fit replacement for units with service numbers 89017735 or 12583826. Please verify your vehicle’s part number or contact us with your VIN if you are unsure. It is guaranteed to fit the following vehicles:
- 2003-2004 Buick Regal: Electronic Control Module; (LH engine compartment)
- 2003 Buick LeSabre: Electronic Control Module; (LH engine compartment), ID 12583826
- 2003-2004 Buick Park Avenue: Electronic Control Module; (LH front engine compartment)
- 2003 Chevrolet Impala: Electronic Control Module; (LH engine compartment), 3.8L, ID 12583826 or 89017735
- 2003 Chevrolet Monte Carlo: Electronic Control Module; (LH engine compartment), 3.8L, ID 12583826
- 2003 Pontiac Bonneville: Electronic Control Module; (LH engine compartment), ID 12583826
- 2003 Pontiac Grand Prix: Electronic Control Module; (LH front engine compartment), 3.8L, ID 12583826
Frequently Asked Questions About This PCM
Frequently Asked Questions
Do I need to have this programmed by a dealer?
No. We program the module to your specific VIN before we ship it. It arrives ready for installation, saving you time and money.
Where do I provide my VIN?
After you complete your purchase, you will need to send us your 17-digit VIN. We cannot ship the product until we receive this information for programming.
What if my original part number is 12583826?
This module, part number 89017735, is a fully compatible and interchangeable service replacement for 12583826. It will function identically.
Will this fix my car’s hard shifting problem?
If the hard shifting is caused by a faulty PCM, then yes, this part is the correct fix. The PCM controls transmission line pressure and shift points, and failure can lead to poor shifting performance.
Is any other setup required after installation?
In most cases, no. However, some GM vehicles may require a simple security or CASE relearn procedure. This can often be performed by the owner and does not require a specialized scan tool.