Restore Your Vehicle’s Core Performance and Reliability
Is your 2003 Chevy S10 Blazer or GMC S15 Jimmy acting up? If you’re dealing with frustrating issues like random stalling, a persistent Check Engine Light, poor fuel mileage, or a no-start condition, the problem often points to a failing Powertrain Control Module (PCM). As the central computer of your vehicle, the PCM manages everything from fuel injection and ignition timing to transmission shifting. When it falters, the entire vehicle’s performance suffers. This replacement PCM, part number IS 8125815650, is the definitive solution to get your truck running smoothly again.
We take the guesswork and high costs out of the repair. Unlike a generic part that requires an expensive trip to the dealership for programming, this module arrives at your door fully programmed to your vehicle’s specific Vehicle Identification Number (VIN). We load the latest GM-certified software, ensuring optimal communication between all your vehicle’s systems. This not only fixes existing problems but can also improve drivability and efficiency by incorporating factory updates you may have missed.
A Technician’s Notebook: The Intermittent Stall Mystery
I once had a 2003 GMC Jimmy S15 in my bay with a problem that was driving the owner crazy. It would stall unpredictably at stoplights, but then start right back up. There were no consistent trouble codes, just a history of random communication faults. We checked fuel pressure, ignition components, and wiring harnesses for hours. Everything seemed fine. On a hunch, I monitored the PCM’s internal temperature data while running the engine. I noticed that right before a stall, the data would freeze. The PCM was failing internally when it got hot. Swapping in a quality, correctly programmed PCM like this one solved the issue instantly. It’s a reminder that sometimes the ‘brain’ itself is the culprit, even without a clear trouble code.
Is Your Blazer Showing These Signs of PCM Failure?
A failing computer can cause a wide range of symptoms. If you’re noticing any of the following, a faulty PCM is a likely cause. This is especially true if you see diagnostic trouble codes (DTCs) like P0601, P0605, or P0606.
- ✔ Check Engine Light is on or flashing
- ✔ Vehicle refuses to start or has difficulty starting
- ✔ Rough idling or stalling
- ✔ Noticeable drop in fuel economy
- ✔ Harsh or erratic automatic transmission shifting
- ✔ Failure to pass an emissions test
- ✔ Communication errors with your scan tool
Your Straightforward Installation Guide
Installing your new 2003 Blazer S10 PCM is a manageable job for a DIYer with basic tools. On this model, the PCM is typically located in the engine compartment on the right-hand (passenger) side. Follow these steps for a successful installation:
- Safety First: Disconnect the negative terminal from your vehicle’s battery and wait at least 15 minutes to ensure all capacitors in the system are discharged.
- Locate the PCM: Find the module on the passenger side of the engine bay. It’s a metal box with several large multi-pin electrical connectors.
- Disconnect Wiring: Carefully release the locking tabs and unplug all electrical connectors from the old PCM. Avoid forcing them.
- Remove the Old Module: Unbolt the PCM from its mounting bracket and remove it from the vehicle.
- Install the New Module: Bolt the new, pre-programmed PCM into the mounting bracket. Reconnect all electrical connectors, ensuring they click securely into place.
- Reconnect Battery: Reattach the negative battery terminal.
- Perform Security Relearn: You may need to perform a simple key-cycle security relearn procedure. Turn the key to the ‘ON’ position for 10-15 minutes, then ‘OFF’ for 10 seconds. Repeat this 3 times. Your vehicle should then start and run with the new PCM.
Verified Fitment Across a Wide Range of GM Vehicles
This module is a direct replacement for service number IS 8125815650 and is compatible with an extensive list of GM trucks, vans, and cars. Please verify your vehicle is on the list below. We program the module based on the VIN you provide to ensure perfect compatibility.
Compatible Service Numbers: 12581565, 12570557, 12570558, 12576106, 12576869, 12578127, 8125781270, 88864822, 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: Electronic/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
How do I provide my VIN for programming?
After you complete your purchase, you will receive instructions on how to send us your vehicle’s 17-digit VIN. We cannot ship the module until we have this information to perform the programming.
Is any additional programming needed after installation?
No. This PCM comes fully programmed with the latest GM software for your VIN. In most cases, you will only need to perform a simple security relearn procedure, which involves cycling the key and does not require any special tools.
Will this fix my transmission shifting problems?
In many cases, yes. The PCM controls the transmission’s shift points and line pressure. If your current PCM is faulty, it can cause harsh or erratic shifting, and this replacement module is designed to correct those commands.
What is the difference between a PCM, ECM, and ECU?
The terms are often used interchangeably. PCM (Powertrain Control Module) is the most accurate for this part as it controls both the engine and transmission. ECM (Engine Control Module) and ECU (Engine Control Unit) typically refer to a computer that only manages engine functions.
Is this a guaranteed fit for my 2003 Blazer with a 4.3L V6?
Yes. This module is the correct part for a 2003 Blazer S10 or Jimmy S15. By programming it to your specific VIN, we ensure it functions exactly as the original factory module did.