Restore Peak Performance to Your GM Truck or SUV
Is your 1998 GMC Envoy, Chevrolet Blazer, or other compatible GM vehicle suffering from perplexing issues like stalling, erratic shifting, a persistent check engine light, or a no-start condition? The Powertrain Control Module (PCM), the central computer for your engine and transmission, is often the culprit. This genuine, used OEM PCM, part number 16266645, is the reliable and cost-effective solution to get your vehicle running smoothly again. We take the guesswork out of the repair by programming the module specifically to your vehicle’s VIN before it ships, ensuring a seamless installation process.
From the Diagnostic Bay
We had a 1998 Chevy S10 come into the shop with a classic intermittent no-start. The owner had already replaced the battery, starter, and fuel pump, but the truck would still randomly refuse to crank. After hours of chasing wires, we connected our high-level scan tool and noticed intermittent communication loss with the PCM. When the module was cold, it worked fine, but as the engine bay warmed up, internal circuits would fail. We installed one of these VIN-programmed PCMs, performed the quick security relearn, and the truck fired up every single time. It’s a common failure mode on these older GM platforms, and a correctly programmed module is the only true fix.
Is Your Vehicle Exhibiting These Symptoms?
A failing PCM can manifest in numerous ways, often mimicking other component failures. If you’re experiencing any of the following, a faulty engine computer could be to blame:
- ✔ Persistent Check Engine Light (CEL) with various trouble codes.
- ✔ Engine stalling or shutting off while driving.
- ✔ Rough or unstable idling.
- ✔ Noticeable decrease in fuel economy.
- ✔ Harsh or delayed automatic transmission shifting.
- ✔ Complete no-start or no-spark condition.
- ✔ Communication errors with diagnostic scan tools.
- ✔ Failure to pass emissions testing.
The Right Solution: A VIN-Programmed 1998 Envoy PCM
Don’t settle for a generic, unprogrammed module that will require an expensive trip to the dealership. Our process is designed for the DIY mechanic and professional alike. We flash this tested, used OEM computer with the latest GM-certified software updates specific to your vehicle’s VIN. This ensures all factory parameters for your engine, transmission, and emissions systems are correctly loaded. This 1998 Envoy PCM is a direct replacement for part number 16266645 and several other interchangeable numbers, providing broad compatibility across a wide range of GM trucks and vans from that era.
Upon installation, the only remaining step is a simple security relearn procedure (often called a CASE relearn), which can typically be done in your driveway without special tools. This syncs the new computer with your vehicle’s anti-theft system. By handling the critical programming beforehand, we save you time, money, and the headache of dealing with dealership service departments.
Key Features & Benefits:
- ✔ VIN-Programmed: Arrives ready for installation, flashed with your vehicle’s specific software.
- ✔ OEM Quality: A genuine, used GM part ensures perfect fitment and reliable operation.
- ✔ Cost-Effective Repair: Avoids the high cost of a new module and dealership programming fees.
- ✔ Wide Compatibility: Direct replacement for part numbers 09355699, 16266645, 9355699, 16250279, 16258815, 09366810, and 9366810.
Frequently Asked Questions
Do I need to have this computer programmed?
No. We handle all the programming for you before shipping. Simply provide your vehicle’s 17-digit VIN during or after checkout, and we will flash the module with the correct GM software for your specific vehicle.
Is this a new part?
This is a high-quality, tested, and fully functional used OEM part sourced from a salvaged vehicle. This ensures compatibility and reliability that often exceeds aftermarket alternatives.
What is a security relearn or CASE relearn procedure?
This is a simple procedure required by GM’s anti-theft system to synchronize the new PCM with your vehicle’s ignition key. It typically involves a series of key turns and waiting periods and can be done without any special tools. Instructions are widely available online for your specific model.
Where is the PCM located on my 1998 GMC Envoy?
On the 1998 GMC Envoy, as well as the Blazer and Jimmy, the PCM is typically located in the engine compartment on the right-hand (passenger) side, often near the firewall or inner fender.
Will this fix my transmission shifting problems?
In many cases, yes. The PCM controls the transmission’s shift points and line pressure. If your shifting issues are caused by a faulty computer, this programmed replacement will resolve them. However, it will not fix mechanical issues within the transmission itself.