Restore Peak Performance to Your GM Truck or SUV
Is your 2003 Blazer, Jimmy, or other GM vehicle suffering from frustrating issues like intermittent stalling, erratic shifting, a persistent check engine light, or a no-start condition? These are classic signs of a failing Powertrain Control Module (PCM), the computer that serves as the brain for your engine and transmission. This replacement PCM, part number 12570558, is the definitive solution to get your vehicle running reliably again. We take the guesswork and hassle out of the repair by programming the module specifically for your vehicle using your VIN. This ensures it arrives with the latest GM software updates, ready for a straightforward installation.
From the Diagnostic Bay: The Ghost in the Machine
I remember a 2003 GMC Jimmy S15 that came into my shop with a problem that was driving the owner crazy. It would randomly refuse to start, but only after it was warm. Other times, it would stumble and hesitate while accelerating. There were no consistent trouble codes, just a history of random misfires. We checked fuel pressure, spark, and sensors—all were fine. After hours of diagnostics, we connected a scope to the PCM’s power and ground circuits and finally saw it: intermittent voltage drops inside the module itself. The internal processor was failing under heat. Replacing it with a quality, correctly programmed 2003 Blazer S10 PCM solved everything instantly. It’s a reminder that sometimes the most baffling electrical gremlins live inside the main computer.
Is Your Vehicle Showing These Telltale Symptoms?
A failing PCM can manifest in numerous ways. If you’re experiencing any of the following, this module is likely the solution you need.
- âś” Unexplained Check Engine Light (CEL) illumination
- âś” Diagnostic Trouble Codes (DTCs) such as P0601, P0602, or P0606
- âś” Vehicle refuses to start or has intermittent starting issues
- âś” Poor or declining fuel economy
- âś” Harsh or erratic automatic transmission shifting
- âś” Engine stalling, sputtering, or running rough
- âś” Failure to pass state emissions testing
A Straightforward Guide to Installation
Replacing the PCM is a job most DIY mechanics can handle in their own driveway. Follow these steps for a successful installation.
- Safety First: Disconnect the negative terminal from your vehicle’s battery and secure it away from the post.
- Locate the PCM: On most S10 Blazers and Jimmys, the PCM is located in the engine compartment on the right-hand (passenger) side, near the firewall or inner fender.
- Disconnect Connectors: Carefully release the locking tabs and unplug the wiring harness connectors from the old module. Avoid forcing them.
- Remove the Old Module: Unbolt the PCM from its mounting bracket and remove it from the vehicle.
- Install the New Module: Mount your new, pre-programmed PCM onto the bracket and securely plug in all wiring harness connectors. You should hear or feel a click.
- Reconnect Battery: Re-attach the negative battery terminal.
- Perform Security Relearn: You will need to perform the GM Security Relearn Procedure. This typically involves turning the key to ‘ON’ for 10-15 minutes, then ‘OFF’ for 10 seconds, and repeating this cycle three times. This allows the new PCM to sync with your vehicle’s anti-theft system. Your vehicle will not start until this is completed.
Verified Vehicle Compatibility
This module is a direct-fit replacement for a wide range of GM vehicles. Please confirm your model and engine below. This part is a compatible replacement for service numbers: 12581565, 8125815650, 12570557, 12570558, 12576106, 12576869, 12578127, 8125781270, 88864822, and 89017733.
- ASTRO 03: Electronic Control Module; (LH front by battery)
- AVALANCHE 2500 03: Electronic Control Module; (LH front under battery)
- BLAZER S10/JIMMY S15 03: Electronic Control Module; (RH front engine compartment)
- CTS 04: Electronic Control Module; (RH engine compartment), Base, ID 12581565
- CORVETTE 04: Electronic Control Module; (RH engine compartment), ID 12581565
- EXPRESS/SAVANA VANS (1500, 2500, 3500) 03: Electronic Control Module; (LH rear engine compartment)
- S10/S15/SONOMA 03: Electronic Control Module; (RH front engine compartment), 4.3L
- SAFARI (GMC) 03: Electronic Control Module; (LH front by battery)
- SIERRA/SILVERADO 1500 03: Electronic Control Module; (LH front under battery), w/4.3L
- SIERRA/SILVERADO 2500/3500 03: Powertrain Control Module; (LH front under battery), gasoline, 8.1L
- SUBURBAN 2500 03: Electronic Control Module; (LH front under battery), 8.1L
- YUKON XL 2500 03: Electronic Control Module; (LH front under battery), 8.1L
Frequently Asked Questions
2003 Blazer S10 PCM
Why do you need my VIN?
Your VIN (Vehicle Identification Number) is essential for us to program the with the exact software for your truck’s engine, transmission, and factory options. This ensures perfect compatibility and function right out of the box.