Is Your 1998 GMC Envoy Running Rough?
If you’re dealing with frustrating issues like a persistent check engine light, poor fuel economy, stalling, or a no-start condition, the problem might be the brain of your vehicle: the Powertrain Control Module (PCM). The PCM is the central computer that manages everything from fuel injection and spark timing to transmission shifting. When it fails, it can cause a wide range of confusing and performance-robbing symptoms, leaving your reliable GM truck or SUV feeling unpredictable and unsafe.
From the Diagnostic Bay
I remember a 1998 Chevy S10 that came in with the weirdest problem. The owner said it would randomly stall at stoplights, but only after it was fully warmed up. There were no consistent codes, just a general feeling that the truck had lost its power. We checked the fuel pressure, ignition system, and sensors—all were fine. On a hunch, we monitored the PCM data stream and noticed the injector pulse width was erratically dropping out. We swapped in a pre-programmed PCM, and the truck ran like new. It’s a classic case of an internal PCM fault that doesn’t always throw a specific code, making it a headache to diagnose without experience.
Direct-Fit Solution: The 1998 Envoy PCM
This isn’t just a replacement part; it’s a complete, ready-to-install solution for your vehicle. We take a genuine, used GM PCM and program it specifically to your vehicle’s Vehicle Identification Number (VIN). This critical step ensures that the computer has the correct software and calibrations for your Envoy’s specific engine, transmission, and options. By flashing it with the latest updates from GM, we ensure optimal performance and efficiency, restoring the smooth operation you expect.
Common Symptoms of a Failing PCM:
- ✔ Check Engine Light is on with various or no specific codes.
- ✔ Engine stalling or shutting off while driving.
- ✔ Noticeable decrease in fuel mileage.
- ✔ Engine misfires, stumbles, or runs rough.
- ✔ Harsh or erratic automatic transmission shifting.
- ✔ Vehicle fails to start, even with a good battery and starter.
- ✔ Communication errors with diagnostic scan tools.
Replacing your faulty computer with our VIN-programmed unit eliminates the need for an expensive trip to the dealership for programming. The process is simple: place your order, provide us with your vehicle’s VIN, and we’ll handle the complex software flashing. The part you receive will be ready for a straightforward installation. Just disconnect the battery, swap the modules, reconnect the battery, and you’re ready to get back on the road.
This module is a direct replacement for multiple part numbers, including 09355699, 16266645, 16250279, 16258815, and 9366810, and fits a wide array of GM trucks and vans from the late 90s. Please see the detailed fitment list to confirm compatibility with your specific vehicle.
Frequently Asked Questions
Do I need to program this computer?
No. This PCM comes fully programmed to your vehicle’s specific VIN before we ship it. It is ready for installation right out of the box.
Is this a new part?
This is a high-quality, tested, used OEM part sourced from a salvaged vehicle. Each unit is inspected and verified to be fully functional before being programmed and shipped.
Why do you need my VIN?
The Vehicle Identification Number (VIN) allows us to load the exact factory software and calibrations for your vehicle’s engine, transmission, and options. This ensures perfect compatibility and performance.
Will this fix my check engine light?
If the check engine light is caused by a faulty PCM, this part will solve the issue. However, we always recommend having a professional mechanic diagnose the codes to confirm the PCM is the point of failure before ordering.
Is installation difficult?
Installation is typically straightforward for someone with basic mechanical skills. It involves disconnecting the vehicle’s battery, unplugging the electrical connectors from the old PCM, unbolting it, and then installing the new one in reverse order.