Restore Peak Performance to Your GM Truck or Van
Is your 2003 GMC Sierra 3500, Silverado, or Express van running erratically? If you’re dealing with frustrating issues like random stalling, poor fuel mileage, a persistent Check Engine Light, or a no-start condition, the problem often points directly to a failing Powertrain Control Module (PCM). As the brain of your vehicle’s engine and transmission, a faulty PCM can cause a host of confusing symptoms that are difficult to diagnose. I’ve seen it countless times in my 20+ years in the shop: a perfectly good engine held back by a failing computer.
This isn’t just a replacement part; it’s a complete, ready-to-install solution. We take the guesswork and extra expense out of the equation by programming this module specifically for your vehicle using your VIN. This ensures it arrives with the latest GM software updates, ready for a straightforward installation. You get a reliable fix that restores the precise engine management your vehicle had when it left the factory, without the need for an expensive trip to the dealership for programming.
From the Diagnostic Bay: The Ghost in the Machine
A customer brought in his ’03 Silverado 2500 with the 8.1L. The complaint was intermittent stalling at stoplights and a weird, delayed shift from 1st to 2nd gear, but only when cold. There were no consistent trouble codes, just a random misfire code that would pop up and disappear. He’d already replaced spark plugs, wires, and even the throttle position sensor. After checking fuel pressure and finding no vacuum leaks, I hooked up my high-end scanner to monitor live data. I noticed the PCM was commanding bizarre fuel trim adjustments right before it would stall. On a hunch, I gently tapped on the PCM casing with a screwdriver handle, and the engine immediately sputtered. That confirmed it: an internal failure in the module. A new, programmed 2003 GM Powertrain Control Module fixed everything instantly. It’s a classic case where the computer itself is the hidden culprit.
Is Your GM Truck or Van Showing These Signs?
A failing PCM can manifest in many ways. If you’re experiencing any of the following, this module is the likely solution.
- ✔ Unexplained Check Engine Light (CEL) illumination
- ✔ Diagnostic Trouble Codes (DTCs) such as P0601 (Internal Control Module Memory Check Sum Error) or P0606 (PCM Processor Fault)
- ✔ Vehicle refuses to start or has hard starting issues
- ✔ Poor or erratic automatic transmission shifting
- ✔ Noticeable decrease in fuel economy
- ✔ Stalling, stumbling, or hesitation during acceleration
- ✔ Failed emissions inspection
Your Straightforward PCM Installation Guide
Installing your new 2003 GM Powertrain Control Module is a manageable job for a DIYer. Since it comes pre-programmed, you won’t need any special scan tools for setup, though a security relearn is required.
- Safety First: Disconnect the negative terminal from your vehicle’s battery to prevent any electrical shorts.
- Locate the PCM: On most trucks and SUVs like the Sierra or Yukon, the PCM is located under the hood on the driver’s side, near the battery. On Express and Savana vans, it’s typically in the rear of the engine compartment on the driver’s side.
- Disconnect Connectors: Carefully release the locking tabs and disconnect all wiring harness connectors from the old module. They are color-coded to prevent mix-ups.
- Remove the Old Module: Unbolt the PCM from its mounting bracket and remove it from the vehicle.
- Install the New Module: Seat the new, pre-programmed PCM into the bracket and secure it with the mounting bolts. Reconnect the wiring harnesses, ensuring they click securely into place.
- Reconnect Battery: Re-attach the negative battery terminal.
- Perform Security Relearn: This is a critical step. Turn the key to the ‘ON’ position (don’t start the engine) for 10-15 minutes. The ‘Security’ light on the dash should turn off. Turn the key off for 10 seconds. Repeat this cycle two more times (for a total of three cycles). After the third cycle, the vehicle will have relearned the new PCM and should start normally.
Verified Fitment for Your GM Vehicle
This module, part number 12576106, is a direct replacement for a wide range of GM vehicles. It is compatible with multiple service numbers including 12581565, 12570557, and 89017733. Please verify your vehicle is on the list below. After purchase, you must provide your VIN so we can ensure perfect programming.
ASTRO 03 (LH front by battery)
BLAZER S10/JIMMY S15 03 (RH front engine compartment)
CTS 04 Base, ID 12581565 (RH engine compartment)
CORVETTE 04 ID 12581565 (RH engine compartment)
EXPRESS 1500/2500/3500 VAN 03 (LH rear engine compartment)
S10/S15/SONOMA 03 4.3L (RH front engine compartment)
SAFARI (GMC) 03 (LH front by battery)
SAVANA 1500/2500/3500 VAN 03 (LH rear engine compartment)
SIERRA 1500 PICKUP 03 4.3L (LH front under battery)
SIERRA 2500 PICKUP 03 8.1L Gasoline (LH front under battery)
SIERRA 3500 PICKUP 03 8.1L Gasoline (LH front under battery)
SILVERADO 2500 PICKUP 03 8.1L Gasoline (LH front under battery)
SILVERADO 3500 PICKUP 03 8.1L Gasoline (LH front under battery)
SUBURBAN 2500 03 8.1L (LH front under battery)
YUKON XL 2500 03 8.1L (LH front under battery)
By choosing this pre-programmed 2003 GM Powertrain Control Module, you’re not just buying a part; you’re getting a reliable, cost-effective solution that puts you back in control of your vehicle’s health and performance. Get your truck or van running right again.
Why do you need my VIN?
Your Vehicle Identification Number (VIN) is essential for us to program the module with the correct software for your vehicle’s specific engine, transmission, and options. This ensures seamless communication between all vehicle systems and guarantees compatibility.
Is this part difficult to install?
The physical replacement is straightforward for most DIYers with basic tools. The most important part is performing the security relearn procedure correctly after installation, which does not require any special tools.
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 shifting issues are electronic in nature and caused by a faulty module, this part will resolve them.
What if my original part number is different?
This module replaces several service numbers, including 12581565, 12570557, and 89017733. As long as your vehicle and engine option are on our compatibility list, this module will function correctly as a replacement.
Do I need to have my keys reprogrammed?
No. The GM Passlock security system of this era is tied to the vehicle’s Body Control Module (BCM), not the PCM. Performing the security relearn procedure described in the installation guide is all that’s needed to sync the new PCM to your vehicle.