End the Frustration of an Unreliable Ride
Is your truck or SUV suffering from baffling issues like a persistent check engine light, erratic shifting, a rough idle, or even a no-start condition? These are classic signs that the brain of your vehicle, the Powertrain Control Module (PCM), is failing. Don’t let a faulty computer keep you off the road. This direct-replacement PCM, service number 12586242, is the definitive solution to restore your vehicle’s performance, reliability, and your peace of mind.
Warning Signs and How to Overcome Them
A failing PCM can manifest in numerous ways, often leading to costly misdiagnoses. By replacing it, you can solve these common problems and regain the smooth, dependable operation you expect from your vehicle. Look out for these indicators:
- ✔ Persistent and unexplained Check Engine Light (CEL).
- ✔ Diagnostic Trouble Codes (DTCs) related to module communication, such as U0100, or processor faults like P0601 or P0606.
- ✔ Harsh or delayed automatic transmission shifting.
- ✔ A noticeable drop in fuel economy.
- ✔ Engine stalling, stumbling, or misfiring unexpectedly.
- ✔ The vehicle cranks but refuses to start.
A Mechanic’s Story: The Ghost in the Machine
I once had a 2004 Sierra in the shop that was driving its owner crazy. It would randomly stall at red lights, but never threw a consistent code. The owner had already replaced the fuel pump and a handful of sensors. We checked all the wiring and grounds, but everything looked perfect. On a hunch, we connected a scope to the PCM’s main processor. We found intermittent signal drops—the computer was essentially ‘blacking out’ for a split second. We installed a VIN-programmed PCM like this one, and the truck ran flawlessly. It wasn’t a ghost; it was just a tired computer that needed to be retired. This simple swap saved the owner from endless parts-chasing and restored his confidence in his truck.
Guided Installation to Restore Peace of Mind
We make this repair as straightforward as possible. Because this module arrives programmed specifically for your vehicle’s VIN with the latest GM software updates, you can often get back on the road in under an hour. Here’s a simple guide to get you started:
- Safety First: Always disconnect the negative terminal from your vehicle’s battery before beginning any work on the electrical system.
- Locate the Old PCM: On most compatible GM trucks and SUVs, the PCM is located in the engine bay, either on the driver’s side fender well (under the battery tray) or next to the airbox.
- Disconnect and Remove: Carefully unplug the electrical connectors. They have locking tabs that need to be released. Once disconnected, unbolt the old module from its mounting bracket.
- Install the New Module: Seat your new, pre-programmed 2004 Avalanche 1500 PCM into the bracket and tighten the mounting bolts. Reconnect the electrical harnesses, ensuring they click securely into place.
- Reconnect Power: Reattach the negative battery terminal.
- Perform Relearn Procedure: In most cases, you will need to perform a security relearn (often called a Passlock or CASE relearn) to sync the new PCM with your vehicle’s anti-theft system. This procedure can typically be done without special tools and instructions are widely available online or in service manuals.
Pro Tip: Check Your Grounds!
Before installing your new PCM, take five extra minutes to inspect and clean the main engine and chassis ground connections. A corroded or loose ground can cause voltage issues that mimic PCM failure and can even damage a new module. A little preventative maintenance goes a long way!
Tailored Fit for Your Ride
This module is a direct replacement for service number 12586242 and is compatible with a wide range of 2004 General Motors vehicles. Please verify your service number to ensure a perfect match. This part fits the following vehicles:
- AVALANCHE 1500 04 (LH front under battery)
- ENVOY XL/XUV 04 (5.3L, next to air box)
- ESCALADE / ESV / EXT 04 (LH front under battery)
- HUMMER H2 04 (LH front under battery)
- ISUZU ASCENDER 04 (5.3L, LH engine)
- RAINIER 04 (5.3L, next to air box)
- SIERRA 1500 / 2500 / 3500 / DENALI 04 (Gasoline, LH front under battery)
- SILVERADO 1500 / 2500 / 3500 04 (Gasoline, w/o hybrid, LH front under battery)
- SSR 04 (next to air box)
- SUBURBAN 1500 / 2500 04 (LH front under battery)
- TAHOE 04 (LH front under battery)
- TRAILBLAZER EXT 04 (5.3L, next to air box)
- YUKON / XL 1500 / XL 2500 04 (LH front under battery)
This unit is a guaranteed fit for multiple service numbers, including: 19299226, 89017738, YFKD, YFKF, YFKH, YFKJ, YFKX, YFXL, YFXM, YFXN, YFXP, and YHTN. Ordering this programmed 2004 Avalanche 1500 PCM ensures you get the right component, updated and ready for your specific vehicle.
Frequently Asked Questions
Do I need to do anything after I purchase?
Yes. After placing your order, you must provide us with your vehicle’s 17-digit VIN (Vehicle Identification Number). We use this to load the correct, factory-updated software onto the module before shipping it to you.
What is a security relearn or CASE relearn?
This is a simple procedure required on most GM vehicles to synchronize the new PCM with your vehicle’s anti-theft and crankshaft position sensor systems. It usually involves a sequence of turning the key on and off. Instructions are readily available online for your specific model and are necessary for the vehicle to start and run correctly.
Is this a plug-and-play part?
It’s as close as it gets. Because we program it to your VIN, you will not need a trip to the dealer for expensive programming. The only additional step for you is the security relearn procedure after physical installation.
Will this fix my transmission shifting problems?
In many cases, yes. The PCM controls both engine and transmission functions. If the module’s internal drivers or logic for the transmission have failed, replacing it can restore crisp, proper shifting. However, it will not fix mechanical issues within the transmission itself.
How do I find my original service number?
The service number is printed on a sticker on your original PCM. You can compare it to the list of compatible numbers (12586242, YFKH, etc.) in this listing to confirm fitment.