Is Your 1998-2000 GMC Envoy Running Rough or Not Starting At All?
If you’re dealing with frustrating and unpredictable issues like your Envoy stalling at a stoplight, refusing to start on a cold morning, or throwing random, inexplicable check engine light codes, you’re not alone. As a mechanic with over two decades of experience under the hood of these GM trucks and SUVs, I’ve seen these symptoms countless times. The problem often points directly to a failing Powertrain Control Module, or PCMโthe central computer that manages everything from fuel delivery and spark timing to transmission shifting.
Understanding Why Your Envoy’s PCM Fails
The PCM in your 1998-2000 Envoy is located in the engine bay (typically on the right-hand side), where it’s constantly exposed to intense heat cycles and engine vibration. Over 20+ years, this harsh environment takes its toll. The delicate internal circuits and solder joints can develop microscopic cracks, leading to intermittent connections. This is why the symptoms can seem so randomโone day the truck runs fine, the next it won’t start. It’s not a matter of if these original modules will fail, but when.
“A customer’s ’99 Envoy came in last week with these exact symptoms. It would crank but wouldn’t fire up. He had already replaced the fuel pump and ignition module, but the problem remained. My professional scan tool couldn’t even establish communication with the PCM, which is a dead giveaway. After verifying the module had proper power and ground, we confirmed the PCM itself was internally faulty. Installing a VIN-programmed module like this one resolved all the issues, and he was back on the road the same day.”
The Guaranteed Solution: A VIN-Programmed PCM
Don’t just replace your faulty module with a used one from a junkyard that could fail tomorrow. This is a new, reliable Powertrain Control Module that we program specifically for your vehicle before it ships. All you have to do is provide us with your Envoy’s 17-digit Vehicle Identification Number (VIN) during checkout. We then load it with the latest, most stable software updates from GM, ensuring your engine and transmission perform exactly as the factory intended.
- โ Solves Common Issues: Eliminates no-start conditions, stalling, rough idle, poor fuel economy, and false diagnostic trouble codes (DTCs).
- โ VIN-Programmed for Your Vehicle: Arrives with the correct software for your Envoy’s specific engine, transmission, and options.
- โ True Plug-and-Play: Once you perform a simple security relearn (no tools required), your vehicle will start and run correctly. No trip to the dealer is needed.
- โ Restores Performance: Corrects erratic transmission shifting and restores smooth power delivery.
- โ Direct Fit Replacement: Guaranteed to be compatible with the original part numbers, including 16263494, 16265035, and 8162634940.
Installation and Security Relearn
Replacing the PCM is a straightforward job. First, disconnect the battery. The module is located in the right-front of the engine compartment. Simply unbolt the old unit, disconnect the wiring harnesses, and install the new one. After you reconnect the battery, you will need to perform a GM Passlock security relearn. This procedure syncs the new PCM to your vehicle’s anti-theft system and typically involves turning the key to the ‘ON’ position for 10-12 minutes, then ‘OFF’, and repeating two more times. This simple step is crucial and ensures your Envoy will start and run with the new module.