Is Your Sierra 3500 Running Rough?
If your 2003-2007 GMC Sierra 3500 is suddenly stalling, shifting erratically, or showing a persistent check engine light, the problem might be its electronic brain: the Powertrain Control Module (PCM). As an experienced technician, I’ve seen firsthand how a failing PCM can turn a reliable workhorse into a source of constant frustration. It can cause issues that seem unrelated, from poor fuel economy to a complete no-start condition, leaving you stranded and scratching your head.
The Direct-Fit, Programmed Solution
This isn’t just a replacement part; it’s a complete solution. We take a genuine GM engine computer, service number 28042802, and professionally program it specifically for your truck using your Vehicle Identification Number (VIN). This critical step ensures all communication between the engine, transmission, and other vehicle systems is perfectly synchronized. We load the very latest software updates from GM, which often correct factory bugs and improve performance and efficiency. When you receive this module, it’s ready for a straightforward installation, saving you the time and expense of a dealership visit for programming.
Expert Pro Tip: Check Your Grounds Before You Swap
In my 20+ years in the shop, I’ve seen countless PCMs replaced when the real culprit was a simple, corroded ground wire. Before you install your new module, take 10 minutes to inspect and clean the main ground connections. On these GM trucks, there’s a critical ground strap from the back of the cylinder head to the firewall and another from the engine block to the frame. A poor ground can cause low voltage, creating confusing symptoms that mimic a failed PCM. A wire brush and some dielectric grease can save you a world of diagnostic headaches.
Symptoms of a Failing 2003-2007 Sierra 3500 PCM
A faulty engine computer can manifest in numerous ways. If you’re experiencing any of the following, a new PCM is the likely fix:
- โ Unexplained Check Engine Light (CEL) with various communication codes.
- โ Engine stalling or shutting off while driving.
- โ Harsh or erratic automatic transmission shifting.
- โ The engine cranks but refuses to start.
- โ Noticeable decrease in fuel mileage.
- โ Misfire codes that don’t resolve with new plugs or coils.
Plug-and-Play Installation: No Dealer Visit Required
Installing your pre-programmed PCM is a job most DIYers can handle in under an hour. Hereโs a general guide:
- Safety First: Disconnect the negative terminal from your truck’s battery.
- Locate the PCM: On most Sierra models, it’s found in the engine bay on the driver’s side, under or near the battery tray.
- Disconnect Connectors: Carefully unclip the wiring harness connectors from the old PCM. They have locking tabs, so be gentle to avoid damage.
- Remove the Old Module: Unbolt the PCM from its mounting bracket.
- Install the New PCM: Mount your new, pre-programmed module in place and securely reconnect the wiring harnesses. You should hear a distinct ‘click’ as they lock.
- Reconnect Battery: Reattach the negative battery terminal. The vehicle may need to complete a security relearn procedure, which typically involves turning the key to the ‘ON’ position for 10-15 minutes.
Guaranteed Compatibility
This module is a direct replacement for a wide range of GM trucks and SUVs. It is compatible with service numbers 89017750, 12582605, 12589463, 12602802, 89017734, and 28042802. Simply provide your VIN at checkout, and we’ll handle the rest, ensuring you get a part that works perfectly right out of the box.