Is Your 2003 S10, S15, or Sonoma Running Rough?
If you’re dealing with a frustrating check engine light, erratic engine behavior, stalling, or poor fuel economy in your truck, a failing Powertrain Control Module (PCM) is often the culprit. As the central computer for your engine and transmission, its proper function is critical. Over my 20+ years in the shop, I’ve seen countless GM trucks from this era develop these exact issues due to PCM component failure. This isn’t just a part; it’s the solution to getting your reliable truck back on the road.
Expert Diagnostic Story: “A customer’s 2003 GMC Sonoma with the 4.3L V6 came in last week with intermittent stalling at stoplights and a persistent P0300 random misfire code that wouldn’t go away, no matter what tune-up parts we threw at it. After confirming fuel pressure and spark were good, we hooked up our scope to the injector drivers at the PCM. We found the signal for cylinder 4 was dropping out randomly. A quick inspection of the PCM connectors showed no corrosion, confirming our suspicion: the driver circuit inside the original module had failed. We installed one of our pre-programmed PCMs, performed the security relearn, and the truck ran perfectly. It’s a classic failure mode for these units.”
The Direct Solution: Programmed and Ready to Install
This isn’t a generic, one-size-fits-all module. We take the guesswork and dealer expense out of the equation. When you order, you provide us with your vehicle’s VIN. We then flash this PCM with the latest, most stable official GM software specific to your truck. This ensures perfect compatibility and performance right out of the box.
- โ VIN-Specific Programming: Flashed with the newest GM updates for your exact vehicle.
- โ Solves Common Issues: Corrects problems like check engine lights, no-start conditions, harsh shifting, and poor performance.
- โ No Dealer Required: This module is prepared for installation, saving you a costly trip to the dealership for programming.
- โ Guaranteed Compatibility: A direct replacement for a wide range of service numbers, ensuring a perfect match.
Easy Installation Guide for your 2003 S10 Sonoma PCM
Replacing the PCM on your S10 or Sonoma is a straightforward job you can do in your own driveway. For the 4.3L models, the module is located in the right-front of the engine compartment.
- Safety First: Disconnect the negative terminal from your truck’s battery.
- Locate the PCM: Find the module on the passenger side of the engine bay, typically near the firewall or inner fender.
- Disconnect Connectors: Carefully unlatch and remove the electrical harness connectors. Inspect them for any bent pins or corrosion and clean as needed.
- Remove the Old Module: Unbolt the mounting hardware holding the original PCM in place and remove it from the vehicle.
- Install the New Module: Mount your new, pre-programmed PCM and secure it with the original hardware.
- Reconnect Everything: Firmly reconnect the electrical harnesses and then reconnect the negative battery terminal.
- Perform Security Relearn: You will need to perform a simple key-cycle security relearn procedure (often called a CASE learn or Passlock relearn) to sync the new PCM with your truck’s anti-theft system. This typically takes about 30 minutes and instructions are readily available online.
Cross-Reference Part & Service Numbers
This module is a direct replacement for the following part numbers, ensuring it is the correct component for your repair: 12570558, 12581565, 8125815650, 12570557, 12576106, 12576869, 12578127, 8125781270, 88864822, and 89017733.
Verified Vehicle Fitment
This Powertrain Control Module is verified to fit the following vehicles. Please ensure your vehicle and options match the list below.
- 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)
- EXPRESS / SAVANA VANS (1500, 2500, 3500) 2003: Electronic Control Module; (LH rear engine compartment)
- SIERRA / SILVERADO 1500 PICKUP 2003: Electronic Control Module; (LH front under battery), w/4.3L
- SIERRA / SILVERADO (2500, 3500) 2003: Powertrain Control Module; (LH front under battery), gasoline, 8.1L
- AVALANCHE / SUBURBAN / YUKON XL 2500 2003: Electronic Control Module; (LH front under battery), 8.1L
- CTS 2004: Electronic Control Module; (RH engine compartment), Base, ID 12581565
- CORVETTE 2004: Electronic Control Module; (RH engine compartment), ID 12581565