Restore Peak Performance to Your GM Truck or Van
Is your 2003 S10, Sonoma, or other GM vehicle suffering from frustrating, hard-to-diagnose issues? A faulty Powertrain Control Module (PCM) is often the culprit behind problems like erratic idling, poor fuel economy, stalling, or a persistent Check Engine Light. As the central computer for your engine and transmission, its health is critical. This replacement PCM, service number IS 8125815650, is the definitive solution to get your vehicle running reliably again. We take the hassle out of the repair by programming the module to your vehicle’s specific VIN before it ships, ensuring it arrives ready for a straightforward installation.
A Technician’s Notebook: The Ghost in the S10
I had a 2003 S10 with the 4.3L V6 come into the shop that was giving its owner fits. It would start and run fine for a week, then suddenly refuse to start, only to fire right up an hour later. Other times, it would stall at a stoplight. There were no consistent codes, just a history of a P0601 (Internal Control Module Memory Check Sum Error) that would come and go. After verifying the power and ground circuits to the PCM were solid—a critical first step I always perform—we determined the module itself was failing internally. Swapping in a pre-programmed 2003 S10 Sonoma PCM like this one resolved all the intermittent electrical gremlins instantly. The customer was back on the road with a dependable truck, and we had another successful diagnosis in the books.
Is Your Truck Exhibiting These PCM Failure Signs?
A failing engine computer can manifest in numerous ways. If you’re experiencing any of the following, a new PCM is likely the solution you need.
- ✔ Unexplained Check Engine Light illumination, especially with codes like P0601, P0602, or P0606.
- ✔ Vehicle refuses to start or has intermittent starting problems.
- ✔ A noticeable drop in fuel mileage.
- ✔ Engine stalling, stumbling, or running rough.
- ✔ Harsh or erratic automatic transmission shifting.
- ✔ Failure to pass an emissions test due to module-related faults.
Your Straightforward Installation Guide
Installing your new 2003 S10 Sonoma PCM is a job most DIYers can handle with basic tools. For the 2003 S10/Sonoma, the module is typically located in the right-front of the engine compartment.
- Safety First: Always disconnect the negative terminal from your vehicle’s battery and wait at least 15 minutes for capacitors to discharge.
- Locate the PCM: On the S10/Sonoma, it’s usually mounted to a bracket on the passenger side of the engine bay. Other vehicles like the Express/Savana vans have it in the rear of the engine compartment.
- Disconnect the Harnesses: Carefully unclip and remove the electrical wiring harnesses connected to the old module. Inspect the connectors for any corrosion or damage.
- Remove the Old Module: Unbolt the old 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 reconnect the wiring harnesses. You should hear a distinct click as they lock into place.
- Reconnect the Battery: Re-attach the negative battery terminal.
- Perform Security Relearn: You will likely need to perform a simple security relearn procedure. This typically involves turning the key to the ‘ON’ position 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.
Verified Compatibility for Your GM Vehicle
This module is a direct replacement for service number IS 8125815650 and is compatible with a wide range of GM vehicles. Please verify your model and options below. This part replaces numerous other service numbers including: 12581565, 12570557, 12570558, 12576106, 12576869, 12578127, 8125781270, 88864822, and 89017733.
- ✔ S10/S15/SONOMA (2003): Electronic Control Module; (RH front engine compartment), 4.3L
- ✔ BLAZER S10/JIMMY S15 (2003): Electronic Control Module; (RH front engine compartment)
- ✔ ASTRO / SAFARI (GMC) (2003): Electronic Control Module; (LH front by battery)
- ✔ SILVERADO/SIERRA 1500 PICKUP (2003): Electronic Control Module; (LH front under battery), w/4.3L
- ✔ SILVERADO/SIERRA 2500/3500 PICKUP (2003): Electronic Control Module; (LH front under battery), gasoline, 8.1L
- ✔ AVALANCHE 2500 (2003): Electronic Control Module; (LH front under battery)
- ✔ SUBURBAN/YUKON XL 2500 (2003): Electronic Control Module; (LH front under battery), 8.1L
- ✔ EXPRESS/SAVANA 1500/2500/3500 VAN (2003): Electronic Control Module; (LH rear engine compartment)
- ✔ CORVETTE (2004): Electronic Control Module; (RH engine compartment), ID 12581565
- ✔ CTS (2004): Electronic Control Module; (RH engine compartment), Base, ID 12581565
Frequently Asked Questions
How does the VIN programming work?
After you complete your purchase, you will need to provide us with your vehicle’s 17-digit VIN. We use this number to load the exact, correct GM factory software and calibrations for your specific vehicle into the PCM. This ensures it works perfectly right out of the box.
Do I need any special tools for installation?
No special tools are required. Basic hand tools like a socket set and ratchet are all that’s needed to physically swap the module. The only other procedure is the key-cycle security relearn, which requires no tools at all.
Is this a new or used part?
This is a high-quality, tested replacement part guaranteed to meet or exceed original equipment specifications. It is fully inspected and programmed with the latest software for your vehicle.
Will this fix my transmission shifting problems?
In many cases, yes. The PCM also controls transmission functions, including shift points and line pressure. If your transmission issues are electronic and caused by a faulty module, this part will resolve them. It will not fix internal mechanical failures within the transmission.
What is the security relearn procedure?
It’s a simple process to sync the new PCM with your vehicle’s anti-theft system. After installation, turn the ignition key to ‘ON’ (without starting the engine) for 10-15 minutes, until the security light goes out. Turn the key ‘OFF’ for 10 seconds. Repeat this two more times for a total of three cycles. The vehicle should then start and run normally.