Is Your 2004 Sierra 3500 Running Rough?
If your workhorse truck is suddenly stalling, shifting erratically, or throwing a check engine light that won’t go away, a failing Powertrain Control Module (PCM) is often the culprit. As the brain of your truck’s engine and transmission, when the PCM starts to fail, it can cause a host of frustrating and costly problems. You’re not just losing performance; you’re losing time and money when your truck is down.
This is a direct-fit, professionally programmed replacement PCM for your 2004 GMC Sierra 3500. We take the guesswork and high dealership costs out of the equation. Simply provide us with your vehicle’s VIN during checkout, and our technicians will flash this module with the latest GM-certified software specific to your truck. It arrives at your door ready for a straightforward, plug-and-play installation.
Symptoms of a Failing 2004 Sierra 3500 PCM:
- âś” Unexplained Check Engine Light (CEL) illumination
- âś” Engine stalling, stumbling, or refusing to start
- âś” Harsh or incorrect automatic transmission shifting
- âś” A significant drop in fuel economy
- âś” Communication errors with diagnostic scan tools
- âś” False sensor codes appearing even after replacing the sensor
Expert Pro Tip: Check Your Battery Tray First!
In my 20+ years in the shop, I’ve seen countless PCMs on these HD trucks fail due to a simple, overlooked issue: battery acid. The PCM on the 2004 Sierra 3500 is located directly under the battery tray on the driver’s side. A small, slow leak from the battery can drip down, corroding the PCM connectors and eventually seeping into the module itself. Before you install your new PCM, thoroughly clean the battery tray and check the battery for any signs of leakage to prevent damaging the new part.
Plug-and-Play Installation: No Dealer Visit Required
Replacing the brain of your truck might sound intimidating, but we make it simple. Because we program the module to your VIN before shipping, you won’t need a trip to the dealership for expensive programming. This is a job you can confidently do in your own driveway.
- Safety First: Disconnect the negative terminal from your truck’s battery.
- Locate the PCM: On your 2004 Sierra 3500, find the PCM on the driver’s side, mounted to the frame rail beneath the battery tray. You will need to remove the battery to access it.
- Disconnect the Harnesses: Carefully lift the locking tabs and unplug the electrical connectors from the old PCM. Inspect the connectors for any corrosion or damage and clean them with an electrical contact cleaner if necessary.
- Remove the Old Module: Unbolt the old PCM from its mounting bracket.
- Install the New PCM: Mount your new, pre-programmed PCM onto the bracket and securely plug in the electrical harnesses until they click into place.
- Reconnect and Start: Reinstall the battery and connect the negative terminal. Your truck is now ready to start with its new, fully functional PCM. A security relearn procedure may be required, which typically involves turning the key to the ‘ON’ position for 10-15 minutes.
Guaranteed Compatibility
This module is a direct replacement for part numbers 12586243 and 89017739. While it fits a wide range of GM vehicles from 2004, this listing is specifically for a 2004 GMC Sierra 3500 with the 8.1L gasoline engine. Ordering from us ensures you get the correct hardware and software, flashed and ready to restore your truck’s reliability and performance.