Restore Peak Performance to Your GM Truck or Van
If your 2003 Blazer S10 or Jimmy S15 is suffering from frustrating issues like a persistent check engine light, erratic shifting, stalling, or a no-start condition, a failing Powertrain Control Module (PCM) is often the culprit. As a technician with over two decades of experience under the hood, I’ve seen countless vehicles sidelined by a faulty engine computer. This isn’t just a part; it’s the brain of your vehicle, responsible for managing everything from fuel delivery and spark timing to transmission shifting. When it fails, the symptoms can be unpredictable and confusing.
This replacement PCM, part number 88864822, is the definitive solution. We take the guesswork and hassle out of the repair by pre-programming the module specifically for your vehicle using your VIN. This means it arrives at your door loaded with the latest GM software updates, ready for a straightforward installation. You get a reliable fix that restores factory performance and drivability without the expensive trip to a dealership for programming.
A Technician’s Notebook: The Case of the Intermittent Stall
A customer brought in their ’03 GMC Sonoma with the 4.3L V6, a sibling to the Blazer. The complaint was a maddening intermittent stall that only happened after it was fully warmed up. No specific codes were stored, just a generic P0300 random misfire that would pop up occasionally. We checked fuel pressure, ignition components, and sensors—all were fine. On a hunch, I monitored the PCM data stream during a long test drive. Just before it would stall, I saw the injector pulse width data go haywire. The internal processor on the original PCM was failing under heat soak. After installing a VIN-programmed module like this one, the truck ran perfectly. These failures are common due to years of heat cycles and vibration in the engine bay.
Is Your Vehicle Showing These Symptoms?
A failing PCM can manifest in numerous ways. If you’re experiencing any of the following, this module is your likely solution:
- ✔ Persistent Check Engine Light (CEL)
- ✔ Stored diagnostic trouble codes (DTCs) like P0601, P0602, or P0606
- ✔ Vehicle refuses to start or has hard starting issues
- ✔ Poor or erratic automatic transmission shifting
- ✔ A sudden drop in fuel economy
- ✔ Engine stalling, stumbling, or misfiring
- ✔ Failure to pass an emissions inspection
A Straightforward Guide to Installation
Replacing the PCM is a job most DIYers can handle with basic tools. This module is designed for a direct fit, making the process simple. After installation, you may need to perform a security relearn procedure, which can typically be done without special tools.
- Safety First: Disconnect the negative terminal from your vehicle’s battery to prevent any electrical shorts.
- Locate the PCM: On the 2003 Blazer S10/Jimmy S15, the PCM is located in the engine compartment on the right-hand (passenger) side, typically near the firewall or inner fender.
- Disconnect Connectors: Carefully unclip and remove the electrical wiring harnesses from the old module. The levers on the connectors make this easier.
- 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 fasten it.
- Reconnect Everything: Plug the wiring harnesses back into the new module until they click into place. Reconnect the negative battery terminal.
- Perform Security Relearn: Start the vehicle. If it starts and then stalls, you will need to complete the VATS/Passlock security relearn. This procedure typically involves turning the key to ‘ON’ for 10-15 minutes, then ‘OFF’, and repeating this cycle three times. Consult your owner’s manual for the specific steps for your vehicle.
Verified Vehicle Compatibility
This module is a direct replacement for service number 88864822 and is compatible with a wide range of GM vehicles. We program it for your specific model. Please verify your vehicle is on this list:
- 2003 BLAZER S10/JIMMY S15: (RH front engine compartment)
- 2003 S10/S15/SONOMA PICKUP: (RH front engine compartment), 4.3L
- 2003 ASTRO / SAFARI (GMC) VAN: (LH front by battery)
- 2003 EXPRESS / SAVANA 1500/2500/3500 VAN: (LH rear engine compartment)
- 2003 SIERRA / SILVERADO 1500 PICKUP: (LH front under battery), w/4.3L
- 2003 SIERRA / SILVERADO 2500/3500 PICKUP: (LH front under battery), gasoline, 8.1L
- 2003 AVALANCHE 2500: (LH front under battery)
- 2003 SUBURBAN 2500: (LH front under battery), 8.1L
- 2003 YUKON XL 2500: (LH front under battery), 8.1L
- 2004 CADILLAC CTS: (RH engine compartment), Base, ID 12581565
- 2004 CORVETTE: (RH engine compartment), ID 12581565
Frequently Asked Questions
What do I need to do after I purchase?
After completing your purchase, you must send us your vehicle’s 17-digit VIN (Vehicle Identification Number). We cannot ship your order until we receive the VIN, as we use it to load the correct GM-certified software for your specific vehicle.
Is this part difficult to install?
No, this is a direct-fit replacement. Installation involves disconnecting the battery, unplugging the old module, unbolting it, and then installing the new one. The most common post-installation step is a simple security relearn procedure that you can do yourself.
Will this fix my check engine light?
If the check engine light is caused by an internal PCM failure (like codes P0601-P0606), then yes, this module will resolve the issue. However, you should always ensure other potential causes, like faulty sensors or wiring, have been properly diagnosed first.
What is a security relearn or CASE relearn?
The security relearn (VATS/Passlock) syncs the new PCM with your vehicle’s anti-theft system. A CASE (Crankshaft Angle Sensor Error) relearn may sometimes be needed to fine-tune engine timing for optimal performance and to clear certain codes. A professional scan tool is required for the CASE relearn, but it is not always necessary for the vehicle to run properly.
Does this part come with a warranty?
Yes, all of our electronic modules are backed by a comprehensive warranty. Please see the warranty tab on this page for complete details and peace of mind with your purchase.