Restore Peak Performance to Your GM Truck or SUV
Is your GMC Envoy, Chevy Blazer, or S10 running rough, stalling unexpectedly, or throwing a stubborn Check Engine Light? As a technician with over two decades of experience, I’ve seen these symptoms countless times. Often, the culprit isn’t a bad sensor or a vacuum leak, but the very brain of the vehicle: the Powertrain Control Module (PCM). This replacement PCM, part number 16263494, is the definitive solution to get your vehicle running reliably again. We take the guesswork and hassle out of the repair by programming the module with your vehicle’s specific VIN and the latest GM software updates before it even leaves our facility. This ensures a seamless installation and immediate performance restoration.
A Technician’s Notebook
I remember a 1999 GMC Envoy that came into the shop with a frustrating, intermittent no-start condition. The owner had already replaced the battery, alternator, and starter to no avail. The codes were all over the place—mostly communication errors. After checking the main power and ground circuits to the PCM, we found they were solid. On a hunch, we connected a scope and saw the 5-volt reference signal dropping out randomly. That’s a classic sign of an internal PCM failure. We installed a VIN-programmed module just like this one, and the Envoy fired up on the first try and never had the issue again. It’s a fix that restores not just the vehicle, but the owner’s confidence in it.
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, this module is likely the solution you need. The most critical step in diagnostics is recognizing the pattern of a failing computer.
- ✔ Unexplained Check Engine Light with codes like P0601 (Internal Control Module Memory Check Sum Error) or P0605 (Internal Control Module ROM Error).
- ✔ Vehicle refuses to start or stalls intermittently.
- ✔ Harsh or erratic automatic transmission shifting.
- ✔ A noticeable drop in fuel economy.
- ✔ Communication errors with scan tools (U-codes).
- ✔ Engine performance problems like rough idling, hesitation, or misfires that don’t resolve with new plugs or coils.
A Straightforward Guide to Installation
Installing your new 1998-2000 Envoy PCM is a job most DIYers can handle in their own driveway. The location can vary slightly by model, but the process is generally the same. For the GMC Envoy, Jimmy, Blazer, and S10/Sonoma, you’ll typically find it in the engine compartment on the right-hand (passenger) side.
- Safety First: Always disconnect the negative terminal from your vehicle’s battery and wait about 10 minutes for the system capacitors to discharge.
- Locate the PCM: Find the existing module. It’s a metal box with several large electrical connectors.
- Disconnect the Connectors: Carefully unclip and remove the wiring harness connectors from the old PCM. These connectors often have a lever or locking tab that needs to be released first. Avoid pulling on the wires themselves.
- Remove the Old Module: Unbolt the PCM from its mounting bracket. Keep the hardware, as you may need it for the new installation.
- Install the New PCM: Mount your new, pre-programmed module in place and securely fasten it.
- Reconnect Everything: Plug the wiring harness connectors firmly into the new PCM until they click into place. Reconnect the negative battery terminal.
- Final Check: Turn the key to the ‘On’ position for 10-15 seconds before starting the engine. This allows the system to recognize the new module. Start your vehicle and enjoy the restored performance.
Verified Vehicle Compatibility
This module is a direct replacement for service number 16263494 and is also compatible with part numbers 16265035, 8162634940, 218-11787, and 21811787. We guarantee fitment for the following vehicles, provided the part number on your original module matches.
- Envoy / Blazer S10 / Jimmy S15 / Bravada / Hombre (4.3L): 1998-2000
- S10/S15/Sonoma Pickup (4.3L): 1998-2000
- Astro / Safari Van (4.3L): 1999-2001
- Chevy / GMC 1500, 2500, 3500 Pickups (Gasoline): 1999-2000
- Silverado / Sierra 1500 (6-Cylinder): 1999-2000
- Tahoe / Yukon / Escalade (Gasoline): 1999-2000
- Suburban 1500 / 2500 (Gasoline): 1999
- Express / Savana 1500, 2500, 3500 Vans (Gasoline): 1999-2002
Note: For 1998 models, please verify your vehicle has the build date option ZN4. Always confirm the part number on your original module before ordering.