2004 Sierra 3500 PCM 12586242 | VIN-Programmed for Your Truck

Is Your Truck Fighting You? Get Back in Command.

There’s nothing more frustrating than a vehicle you can’t rely on. If your 2004 GMC Sierra 3500 is suddenly plagued by bizarre electrical gremlins, poor fuel economy, a persistent Check Engine Light, or a nerve-wracking no-start condition, the problem often points directly to a failing Powertrain Control Module (PCM). This isn’t just an inconvenience; it’s a loss of confidence in the machine you depend on daily. This VIN-programmed PCM, service number 12586242, is the definitive solution to restore your truck’s performance and your peace of mind.

Warning Signs and How to Overcome Them

A faulty PCM can manifest in numerous ways, often mimicking other component failures. Before you start replacing expensive sensors and parts, see if your truck is exhibiting these classic symptoms of a failing engine computer. This module is the proven fix for these issues and more:

• ✔ Persistent Check Engine Light: Especially for communication-related or internal processor fault codes like P0601, P0602, P0604, or P0606.
• ✔ Engine Stalling or Misfiring: Unpredictable stalling at idle or while driving can be both dangerous and a clear sign of a PCM issue.
• ✔ No-Start Condition: If the engine cranks but won’t start, the PCM may not be properly managing the fuel and spark delivery.
• ✔ Erratic Transmission Shifting: Harsh shifts, getting stuck in a gear, or delayed engagement can be caused by the PCM failing to communicate correctly with the transmission controller.
• ✔ Poor Fuel Economy: A sudden, unexplained drop in MPG is often a result of the PCM not optimizing the engine’s air-fuel mixture.
• ✔ Failed Emissions Test: The inability of the PCM to properly manage engine functions will almost certainly lead to a failed smog check.

The Smart Solution: A Pre-Programmed 2004 Sierra 3500 PCM

Forget the exorbitant costs and scheduling headaches of a dealership visit. We take the complexity out of the repair. When you order, simply provide us with your vehicle’s VIN. Our experts will flash this module with the latest, most stable GM-certified software specific to your truck. It arrives at your door ready to install, transforming a potentially complicated repair into a straightforward, manageable job you can do in your own driveway.

An Expert’s Note: The Diagnostic Dead End

“I remember a customer with a 2004 Silverado 2500, a near twin to the Sierra, who had spent over a thousand dollars chasing a ghost. He’d replaced the throttle body, MAF sensor, and even the fuel pump based on various shops’ advice. The truck still stalled randomly. When he finally brought it to me, I saw a P0601 ‘Internal Control Module Memory Check Sum Error’ code. We installed one of these pre-programmed PCMs, performed the quick security relearn, and the truck ran perfectly. He was thrilled to finally have a reliable workhorse again and kicking himself for not starting with the brain of the operation first.”

Guided Installation to Restore Your Truck’s Health

You don’t need to be a master mechanic to complete this installation. With basic hand tools and a little patience, you can get your Sierra 3500 back to peak condition. Follow these simple steps for a successful replacement.

1. Safety First: Begin by disconnecting the negative terminal of your truck’s battery to prevent any electrical shorts.
2. Locate the PCM: On most 2004 GM trucks like the Sierra and Silverado, the PCM is located under the hood on the driver’s side, often under or near the battery tray.
3. Disconnect the Old Module: Carefully unplug the electrical connectors. They have locking tabs that need to be released—don’t force them. Once disconnected, unbolt the module from its mounting bracket.
4. Install the New PCM: Mount your new, pre-programmed PCM onto the bracket and securely plug in the electrical connectors. You’ll hear a ‘click’ when they’re properly seated.
5. Reconnect and Relearn: Reconnect the negative battery terminal. In most cases, you will need to perform a simple security relearn procedure (often called a CASE relearn). This can typically be done without special tools and involves a sequence of key turns. Instructions are readily available online or we can help guide you.
6. Start and Verify: Start the engine. The Check Engine Light should be off, and your truck should be running smoothly. You’ve just saved yourself a significant amount of time and money.

Tailored Fit for Your GM Ride

This module is a direct replacement for service number 12586242 and is compatible with a wide range of 2004 GM vehicles. Please verify your original part number or one of the compatible service numbers below to ensure a perfect match.

Compatible Service Numbers: 12586242, 19299226, 89017738, YFKD, YFKF, YFKH, YFKJ, YFKX, YFXL, YFXM, YFXN, YFXP, YHTN

Fits Models Including (but not limited to):

• 2004 Cadillac Escalade, ESV, EXT
• 2004 Chevrolet Avalanche 1500
• 2004 Chevrolet Silverado 1500, 2500, 3500 (Gasoline)
• 2004 Chevrolet SSR
• 2004 Chevrolet Suburban 1500, 2500
• 2004 Chevrolet Tahoe
• 2004 Chevrolet Trailblazer EXT (5.3L)
• 2004 GMC Envoy XL, XUV (5.3L)
• 2004 GMC Sierra 1500, 2500, 3500, Denali (Gasoline)
• 2004 GMC Yukon, XL 1500, XL 2500
• 2004 Hummer H2
• 2004 Buick Rainier (5.3L)
• 2004 Isuzu Ascender (5.3L)