Is Your 2004 GM Truck Running Rough?
If you’re dealing with a frustrating check engine light, poor fuel economy, harsh transmission shifting, or even a no-start condition in your 2004 GMC Sierra 1500, a failing Powertrain Control Module (PCM) is a very likely culprit. As the central computer of your truck, the PCM is responsible for managing everything from the air-fuel mixture and ignition timing to transmission shift points and emissions equipment. When it starts to fail, it can cause a wide array of confusing and intermittent problems that can be difficult to diagnose.
The Brain of Your Operation: The 2004 Sierra 1500 PCM
Think of the PCM as the brain of your vehicle’s engine and transmission. It takes in data from dozens of sensors—like the oxygen sensors, crankshaft position sensor, and throttle position sensor—and uses that information to make thousands of calculations per second. These calculations ensure your engine runs efficiently, powerfully, and cleanly. A breakdown in this critical component can leave your truck feeling sluggish, unreliable, or completely immobile. Don’t let a faulty computer keep you off the road. This replacement module is the definitive solution to restore your truck’s factory performance and reliability.
From the Diagnostic Bay
We had a 2004 Yukon XL come in with a problem that was driving the owner crazy. It would randomly stall at stoplights, but only after it was fully warmed up. There were no consistent trouble codes, just a generic P0300 random misfire that would pop up occasionally. We checked fuel pressure, spark, and scanned for vacuum leaks—everything looked perfect. On a hunch, we monitored the data stream from the PCM and noticed the injector pulse width commands would suddenly drop to zero right before a stall. The PCM’s internal driver for the fuel injectors was overheating and failing. We installed a VIN-programmed PCM just like this one, performed the security relearn, and the truck ran perfectly. It’s often the computer itself that’s the ghost in the machine.
Common Symptoms of a Failing PCM
- ✔ Check Engine Light: The most common sign, often with codes related to internal processor failure (e.g., P0601-P0606) or communication errors.
- ✔ No-Start or Hard Starting: The PCM may fail to command the fuel pump or ignition coils to fire.
- ✔ Poor Engine Performance: Noticeable loss of power, hesitation, or stumbling during acceleration.
- ✔ Reduced Fuel Economy: An inefficiently running engine will consume more fuel than usual.
- ✔ Erratic Transmission Shifting: Harsh shifts, delayed engagement, or getting stuck in one gear (limp mode).
- ✔ Intermittent Stalling: The engine may shut off unexpectedly while driving or idling.
- ✔ Failure to Communicate: A scan tool may be unable to connect with the PCM, indicating a total failure.
A True Plug-and-Play Solution
This isn’t just a generic, off-the-shelf part. This is a direct replacement PCM, part number 12586242, that we program specifically for YOUR vehicle before it leaves our facility. Simply provide us with your 17-digit Vehicle Identification Number (VIN) during checkout. We will flash the module with the latest, most up-to-date software and calibrations directly from GM. This critical step ensures that the PCM works seamlessly with your truck’s specific engine, transmission, and factory options. It also ensures compatibility with the vehicle’s anti-theft system (Passlock/VATS), often only requiring a simple security relearn procedure upon installation (instructions provided).
This module is a direct replacement for service numbers 12586242, 19299226, 89017738, and broadcast codes YFKD, YFKF, YFKH, YFKJ, YFKX, YFXL, YFXM, YFXN, YFXP, and YHTN.
Broad GM Compatibility
While this is a perfect fit for the 2004 Sierra 1500 PCM, this versatile module is also the correct electronic control module for a wide range of other 2004 GM trucks and SUVs. If your vehicle is listed below and has a matching service number, this is the correct part for you:
- Chevrolet Silverado 1500/2500/3500
- GMC Sierra 1500/2500/3500 & Denali
- Chevrolet Tahoe & Suburban
- GMC Yukon & Yukon XL
- Cadillac Escalade, ESV, EXT
- Chevrolet Avalanche
- Hummer H2
- Chevrolet SSR
- GMC Envoy XL/XUV
- Chevrolet Trailblazer EXT
- Buick Rainier
- Isuzu Ascender
Please verify your original part number or service ID to ensure a perfect match. Stop chasing symptoms and replace the core of the problem. Order today and get your truck running like it should.
Frequently Asked Questions
Do I need to do any programming or flashing myself?
No. We handle all the programming before we ship the part. All you need to do is provide your vehicle’s 17-digit VIN when you place your order. The module will arrive ready to be installed.
What is a security relearn procedure?
After installation, you may need to perform a simple security relearn to sync the new PCM with your vehicle’s anti-theft system. This procedure typically involves turning the key to the ‘ON’ position for 10-15 minutes, then off, and repeating two more times. It requires no special tools and we can provide instructions.
Where is the PCM located on my 2004 Sierra?
On most GMT800 trucks like the Sierra, Silverado, Tahoe, and Yukon, the PCM is located on the driver’s side of the engine bay, under the battery tray or near the airbox.
Will this fix my specific problem?
If your vehicle’s issues and diagnostic trouble codes point to a faulty PCM, this part is the correct solution. It will resolve problems directly caused by the computer. However, it will not fix underlying mechanical or electrical issues elsewhere in the vehicle, such as a bad sensor or wiring fault.
How do I confirm this is the right part number for me?
The best way is to check the service number on the sticker of your original PCM. This part replaces service number 12586242 and several others listed in the description. Matching this number ensures you are ordering the correct hardware.