Restore Peak Performance to Your GM Truck or Van
If your trusty Chevrolet 2500, Express Van, or GMC Sierra is suddenly giving you headaches—stalling at stoplights, shifting erratically, or throwing a stubborn Check Engine Light—the problem often points to the vehicle’s brain: the Powertrain Control Module (PCM). As a technician with over two decades of experience under the hood, I’ve seen countless drivers chase expensive sensor replacements when the root cause was a failing PCM. This isn’t just a part; it’s the central command center for your engine and transmission. When it falters, everything it controls can become unreliable.
This replacement PCM is the definitive solution. We take the guesswork and hassle out of the repair by pre-programming the module specifically for your vehicle using your VIN. This means it arrives at your door with the latest GM software updates already installed, ready for a straightforward installation. You get a reliable part that restores the original performance, fuel efficiency, and smooth operation you depend on, without the costly trip to a dealership for programming.
Is Your Vehicle Showing These Symptoms?
A failing PCM can cause a wide range of confusing issues. If you’re experiencing any of the following, a faulty module is a likely culprit:
- âś” Unexplained Check Engine Light (CEL) illumination
- âś” Stored diagnostic trouble codes (DTCs) like P0601, P0602, or P0606 (Internal Control Module Memory Check Sum Error)
- âś” Engine stalling, stumbling, or running rough
- âś” Harsh or erratic automatic transmission shifting
- âś” A no-start condition where the engine cranks but won’t fire up
- âś” Noticeable decrease in fuel economy
- âś” Failure to pass an emissions test
From the Diagnostic Bay: The Ghost in the Machine
I remember a 2000 GMC Sierra that came into my shop a few years back. The owner had already replaced the crank sensor, MAP sensor, and a few others trying to solve an intermittent stalling problem that no one could pin down. It would run fine for days, then die at a red light without warning. After hooking up my scan tool and monitoring live data, I noticed the fuel injector pulse width would drop to zero right before it stalled. There were no sensor codes. The only clue was a history code, P0601, that had been cleared. This pointed directly to an internal PCM processor fault. We installed a VIN-programmed PCM, performed the security relearn, and the truck never stalled again. It’s a classic case where throwing parts at a problem costs more than correctly diagnosing the central computer failure from the start.
A Straightforward Guide to Installation
Replacing the PCM in these GM trucks and vans is a job most DIYers can handle with basic tools. Our pre-programming service eliminates the most difficult step. Just follow this general process:
- Safety First: Disconnect the negative terminal from your vehicle’s battery to prevent any electrical shorts.
- Locate the PCM: On most trucks like the Chevy 2500, it’s in the engine bay, on the driver’s side near the fender or firewall. On vans like the Express, it’s often in the LH rear of the engine compartment. Check your service manual for the exact location.
- Disconnect the Connectors: Carefully unclip the wiring harness connectors from the old PCM. These usually have a lever or tab that needs to be released. Avoid pulling on the wires themselves.
- Remove the Old Module: Unbolt the old PCM from its mounting bracket. Keep the hardware, as you’ll need it for the new module.
- Install the New PCM: Mount your new, pre-programmed PCM onto the bracket and securely fasten it.
- Reconnect Everything: Plug the wiring harnesses firmly into the new module until they click into place. Reconnect the negative battery terminal.
- Perform Security Relearn: This is a critical final step. You will likely need to perform a security relearn procedure (often called a Passlock or Passkey relearn) to sync the new PCM with your vehicle’s anti-theft system. A common method is the “10-minute relearn,” which you can easily find instructions for online.
Verified Vehicle Compatibility
This module is a direct-fit replacement for a wide range of GM vehicles. It is compatible with part numbers 16263494, 16265035, and 8162634940. Please verify your vehicle is on this list and provide your VIN upon purchase to ensure perfect programming. This part fits many models including, but not limited to:
- âś” 1999-2000 Chevrolet & GMC 1500/2500/3500 Pickups (Gasoline)
- âś” 1999-2002 Chevrolet Express & GMC Savana 1500/2500/3500 Vans (Gasoline)
- âś” 1999-2001 Chevrolet Astro & GMC Safari Vans
- âś” 1998-2000 Chevrolet S10, GMC Sonoma, Isuzu Hombre (4.3L)
- âś” 1998-2000 Chevrolet Blazer, GMC Jimmy, Oldsmobile Bravada, GMC Envoy
- âś” 1999-2000 Cadillac Escalade, Chevrolet Tahoe, GMC Yukon & Yukon Denali
Note: For some 1998 and 1999 models, please confirm your original module has ID 16263494 or your vehicle has build date option ZN4 where applicable.
Do I need to do any programming myself?
Do I need to do any programming myself?
No. We handle all the programming for you before shipment. We will flash the module with the latest GM-certified software and calibrate it to your vehicle’s specific VIN. This makes the installation process much simpler.
How do I provide my VIN?
After you complete your purchase, you will need to send us your vehicle’s 17-digit VIN (Vehicle Identification Number). You can typically find this on your driver’s side dashboard (visible through the windshield) or on the driver’s side door jamb sticker.
What is a security relearn procedure?
The security relearn (or Passlock relearn) is a simple procedure that syncs the new PCM to your vehicle’s anti-theft system. Without it, your truck may not start. It typically involves turning the key to the ‘ON’ position for 10 minutes, then ‘OFF’, and repeating this cycle three times. We recommend searching for the specific procedure for your model year.
Will this fix my transmission shifting problems?
In many cases, yes. The PCM controls the electronic solenoids in the automatic transmission. If the PCM is faulty, it can cause harsh shifts, delayed engagement, or slipping. A new, correctly programmed PCM often resolves these communication-based transmission issues.
How do I know if this part number is correct?
This module, part #21811787, replaces several original GM part numbers, including 16263494 and 16265035. The best way to ensure compatibility is to match your vehicle to our fitment list. As long as your vehicle is listed, our VIN-based programming will guarantee it functions correctly.