Is Your 1998 GMC Envoy Running Rough or Not Starting?
If you’re dealing with a persistent check engine light, erratic engine performance, transmission shifting problems, or a vehicle that just won’t start, a failing Powertrain Control Module (PCM) is often the culprit. In my 20+ years turning wrenches and diagnosing these exact issues, I’ve seen how a faulty computer can turn a reliable truck into a frustrating driveway ornament. The PCM is the brain of your vehicle, and when it goes, everything it controlsโfrom fuel injection to spark timingโcan fall apart.
This isn’t just a replacement part; it’s a complete, ready-to-install solution. We are offering a genuine, used OEM Engine Computer with service part number 9355699. The key to our service is that we flash the module with the latest official GM software updates, programmed specifically to your vehicle’s VIN. This eliminates the need for expensive dealership programming or specialized scan tools.
Expert Pro Tip from a 20-Year Technician: Before you install your replacement PCM, take five minutes to inspect the main ground connections. On these late-90s GM trucks and SUVs, the engine-to-chassis and battery-to-body ground straps are notorious for corrosion. A poor ground can cause erratic voltage, mimicking the symptoms of a bad PCM and potentially damaging the new unit upon installation. A quick cleaning with a wire brush can save you a major headache.
Why Choose Our Programmed 1998 Envoy PCM?
Over the years, I’ve diagnosed hundreds of no-start or poor-running conditions on GM vehicles from this era. A customer’s ’98 Blazer came in last month with a crank-no-start issue. He’d already replaced the fuel pump and ignition module. After confirming good power and ground at the PCM connector, it was clear the module’s internal driver circuits had failedโa common issue. We installed one of our pre-programmed units, and the truck fired right up. This is the simple, effective fix you’re looking for.
- โ VIN-Programmed for Your Vehicle: We load your vehicle’s specific VIN and the latest GM software updates onto the module before it ships.
- โ True Plug-and-Play: No additional programming is required. Once installed, your vehicle will start and run correctly.
- โ Solves Common Problems: A direct solution for issues like false sensor codes (e.g., O2, MAF), harsh shifting, poor fuel economy, and no-start conditions.
- โ Cost-Effective Repair: Avoids the high labor and programming costs associated with a dealership visit.
- โ OEM Reliability: This is a tested, functional computer sourced from a salvaged vehicle, ensuring OEM quality and fitment.
Simple Installation Guide: Get Back on the Road Fast
You don’t need to be a master mechanic to replace this module. On your 1998 Envoy, the PCM is typically located in the engine bay on the right-hand (passenger) side. Follow these simple steps:
- Safety First: Disconnect the negative terminal from your vehicle’s battery.
- Locate the PCM: Find the module, usually mounted to the inner fender or firewall.
- Disconnect Connectors: Carefully unclip the wiring harness connectors from the old PCM. They have locking tabs that may need to be gently pried up.
- Remove the Old Module: Unbolt the old PCM from its mounting bracket.
- Install the New Module: Bolt your new, pre-programmed PCM into place.
- Reconnect Everything: Firmly plug the wiring harnesses into the new module until they click. Reconnect the negative battery terminal.
- Start the Engine: Your vehicle is now ready to go!
Guaranteed Fitment and Compatibility
This module is a direct replacement for units with service ID 9355699. It is also fully interchangeable with the following part numbers:
16266645, 16250279, 16258815, 09366810
This computer is compatible with a wide range of 1998-1999 GM trucks and vans, including the Chevrolet Silverado, GMC Sierra, Tahoe, Yukon, Suburban, Express, Savana, and more. Please verify your original part number matches to ensure a perfect fit for your specific vehicle and options.