Restore Your Truck’s Core Performance and Reliability
Is your 2004 GMC Sierra 1500 or another GM vehicle giving you headaches? Unexplained stalling, a persistent check engine light, or erratic engine behavior can often be traced back to a failing Powertrain Control Module (PCM). As the ‘brain’ of your vehicle, the PCM controls everything from fuel mixture and ignition timing to transmission shifting. When it falters, your truck’s performance and dependability suffer. This replacement PCM, part number 12586243, is the definitive solution to get your vehicle running right again.
With over two decades of hands-on diagnostic experience, I’ve seen countless vehicles sidelined by faulty electronics. The key to a successful repair is not just replacing the part, but ensuring it communicates perfectly with your specific vehicle. That’s why we take the guesswork out of the equation. We flash this module with the latest official GM software updates, programmed specifically to your vehicle’s VIN. This ensures seamless integration and restores the precise operational parameters your truck was designed with from the factory.
Common Signs of a Failing PCM in Your GM Truck
- ✔ Your vehicle won’t start, or it starts intermittently.
- ✔ You’re experiencing poor fuel economy and sluggish acceleration.
- ✔ The engine runs rough, misfires, or stalls unexpectedly.
- ✔ Your check engine light is on with communication codes like U0100 or internal module codes like P0601, P0605, or P0606.
- ✔ The transmission isn’t shifting correctly or feels jerky.
From the Diagnostic Bay
A customer brought in his ’04 Sierra 1500 with a frustrating problem: it would randomly fail to start, but only after it was warm. No check engine light, no obvious codes. After checking fuel pressure and spark, which were fine, I hooked up my professional scan tool to monitor live data. I noticed the PCM would occasionally stop communicating with other modules right before the no-start condition. After a cooldown period, it would work again. This heat-soak failure is a classic symptom of internal PCM circuit board breakdown. We installed a VIN-programmed module just like this one, and the truck has been starting reliably ever since. It’s a fix that restores peace of mind.
A Straightforward Guide to Installation
Replacing the 2004 Sierra 1500 PCM is a job most DIYers can handle with basic tools. This module is typically located in the engine bay on the driver’s side, under or near the battery. Follow these steps for a smooth installation.
- Safety First: Always disconnect the negative terminal from your vehicle’s battery and wait at least 15 minutes to allow all modules to power down completely.
- Locate the PCM: On most trucks like the Sierra/Silverado, it’s under the battery tray. On other vehicles like the Trailblazer or Envoy, it might be next to the air filter box. Refer to the fitment list for location hints.
- Disconnect the Connectors: Carefully release the locking tabs on the electrical connectors and pull them straight out from the module. Never force them. Inspect the pins for any corrosion or damage.
- Remove the Old Module: Unbolt the PCM from its mounting bracket. It’s usually held by a few small bolts (typically 10mm).
- Install the New Module: Mount your new, pre-programmed PCM securely in the bracket. Reconnect the electrical connectors, ensuring they click firmly into place.
- Reconnect the Battery: Attach the negative battery terminal. The vehicle may need to complete a security relearn procedure, which often involves turning the key to the ‘On’ position for 10-15 minutes before starting.
Verified Vehicle Compatibility List
This module, part number 12586243 (also replaces 89017739), is a direct-fit replacement for a wide range of 2004 and 2005 GM vehicles. Please verify your specific model and options below. Providing your VIN during checkout is essential for correct programming.
- 2004 Sierra 1500 Pickup: (LH front under battery), w/o hybrid option; w/4.3L
- 2004-2005 Cadillac CTS: (RH engine compartment), V-Series, ID 12586243
- 2004 Chevrolet Avalanche 2500, Sierra/Silverado 2500/3500 (8.1L Gas), Suburban/Yukon XL 2500 (8.1L Gas): (LH front under battery)
- 2004 Chevrolet Corvette: (RH engine compartment), ID 12586243
- 2004 Chevrolet Express / GMC Savana Vans (1500/2500/3500): (LH rear engine compartment)
- 2004 Chevrolet SSR, Trailblazer EXT, GMC Envoy XL/XUV, Buick Rainier: (Next to air box), check specific engine/ID
- 2004 Pontiac GTO: Main (LH engine)
- 2004 Chevrolet S10/Blazer, GMC Sonoma/Jimmy: (RH front engine compartment)
- 2004 Chevrolet Astro / GMC Safari: (LH front by battery)
Frequently Asked Questions
What is a VIN-programmed PCM?
It means we load the module with the specific software and calibration file from GM that matches your vehicle’s unique Vehicle Identification Number (VIN). This ensures all factory systems, including the engine, transmission, and anti-theft system, function correctly without a trip to the dealer for programming.
Do I need to send you my old PCM?
No, this is not a repair service and there is no core charge. You are purchasing a replacement module that will be programmed to your VIN before it is shipped to you.
Is this a simple plug-and-play installation?
For most vehicles, yes. Once you install the module, you may need to perform a simple security relearn procedure (often called a ‘key-on’ relearn), which takes about 10-15 minutes and requires no special tools. We include instructions for this common procedure.
Will this fix my check engine light?
If the check engine light is caused by a faulty PCM (e.g., codes P0601-P0606, U0100), this will resolve the issue. However, if the light is on due to other failing sensors or components (like an oxygen sensor or catalyst), those issues will still need to be addressed separately.
How do I provide my VIN?
After you complete your purchase, you will need to send us a message with your 17-digit VIN. We cannot program and ship your module without it. Please double-check the VIN for accuracy before sending.
What if my part number is 89017739?
This module is a direct, compatible replacement for part number 89017739. It will function identically once programmed to your vehicle’s VIN.