Is Your Silverado Running Rough? It Could Be The PCM.
The Powertrain Control Module, or PCM, is the central computer of your 2007-2009 Chevrolet Silverado 1500. It’s responsible for managing everything from fuel injection and ignition timing to transmission shift points and emissions controls. When this critical component begins to fail, it can cause a wide array of confusing and frustrating problems that can be difficult to diagnose. From a persistent Check Engine Light to a truck that won’t start at all, a faulty PCM can bring your daily driver or workhorse to a grinding halt.
This replacement Powertrain Control Module, service number 12635902, is the definitive solution to restore your vehicle’s performance, reliability, and efficiency. We take the guesswork out of the repair by pre-programming the module specifically to your truck’s Vehicle Identification Number (VIN). This ensures that it arrives with the latest GM software updates and is ready for a straightforward installation, saving you the time and expense of a trip to the dealership for programming.
From the Diagnostic Bay
We had a 2008 Sierra 1500 with the 4.3L V6 come into the shop with a complaint of intermittent stalling and a random cylinder misfire code (P0300) that just wouldn’t go away. The owner had already replaced the spark plugs, wires, and even the ignition coil pack, but the problem persisted. After hours of chasing wires and checking sensors, we connected our diagnostic scanner and monitored the live data from the PCM. We noticed the injector pulse width commands were erratic just before a stall. We swapped in a known-good, programmed PCM, and the truck ran perfectly. The original PCM had an internal fault that was causing the intermittent failure, a classic example of how a failing computer can mimic mechanical or sensor issues.
Common Symptoms of a Failing GM PCM
If you’re experiencing any of the following issues with your Silverado, Sierra, or other compatible GM vehicle, a failing PCM is a likely culprit. Validating these symptoms is the first step toward a confident repair.
- ✔ Persistent and illuminated Check Engine Light
- ✔ Unexplained drop in fuel economy
- ✔ Engine stalling, stumbling, or hesitating during acceleration
- ✔ Rough or erratic idling
- ✔ Harsh or delayed automatic transmission shifting
- ✔ No-start or difficult starting condition
- ✔ Communication errors with diagnostic scan tools
- ✔ False sensor codes being stored in memory
The Right Solution for Your 2007-2009 Silverado 1500 PCM
Don’t let a faulty computer keep your truck off the road. This module is a direct-fit replacement for a wide range of GM vehicles and interchanges with multiple service numbers, including 12597125, 12612397, 12594750, 12629019, and 12611549. By providing us with your VIN at checkout, you ensure that the module you receive is a perfect match for your vehicle’s specific configuration and options. This plug-and-play approach simplifies the repair process, although some vehicles may require a security relearn procedure or a Crankshaft Variation (CASE) relearn, which can often be performed without specialized tools.
This module fits a variety of GM models beyond the Silverado, including the Chevrolet Malibu, Cobalt, HHR, Impala, Express Van; GMC Sierra, Savana Van; Pontiac G5, G6, Solstice; Saturn Aura, Sky, and Vue. Please verify the service number on your original part or consult the detailed fitment list to confirm compatibility.
Frequently Asked Questions
Do I need to get this PCM programmed by a dealer?
No. We program the module to your vehicle’s specific VIN before shipping it to you. This ensures it has the correct software and calibrations for your engine, transmission, and options, eliminating the need for a dealership visit for programming.
What is a VIN and why do you need it?
The VIN, or Vehicle Identification Number, is a unique 17-digit code for your specific vehicle. It contains information about the manufacturer, model year, engine, and other factory-installed options. We use the VIN to load the exact GM-certified software your truck needs to run correctly.
Is installation difficult? Can I do it myself?
For many DIY mechanics, the installation is straightforward. The PCM is typically located in the engine bay (on the Silverado, it’s under the battery tray). It involves disconnecting the battery, unplugging the electrical connectors, and unbolting the module. However, some vehicles may require a security relearn procedure after installation, which can usually be done by following a simple key-cycling process found in your owner’s manual or online.
What is a “CASE Relearn” and will I need to do one?
A CASE (Crankshaft Angle Sensor Error) Relearn synchronizes the new PCM with your engine’s crankshaft position sensor. It’s often required to clear certain trouble codes (like P1336) after PCM replacement. While some high-end scan tools can perform this, it is not always necessary for the vehicle to run and drive properly.
How do I know this part will fit my vehicle?
This PCM, part number 12635902, replaces many other GM service numbers. The best way to confirm is to match the service number on your original computer to one of the numbers listed in our description. Our comprehensive fitment list also details the specific makes, models, years, and engine options this part is compatible with.