Is Your GM Truck or Van Running Rough?
If your late-90s Chevrolet, GMC, or Cadillac is suffering from mysterious issues like a persistent check engine light, erratic shifting, poor fuel economy, or even a no-start condition, the culprit is often the very brain of your vehicle: the Powertrain Control Module (PCM). This vital component, also known as the Engine Control Module (ECM), is responsible for managing everything from fuel injection and ignition timing to transmission shift points and emissions controls. When it fails, it can cause a cascade of frustrating and difficult-to-diagnose problems.
From the Diagnostic Bay
I once had a 1999 Suburban in the shop that had its owner chasing his tail for months. He’d replaced the MAP sensor, the throttle position sensor, and even the fuel pump, but it still had a terrible hesitation and would randomly stall. The check engine light was on with a dozen different codes. After checking all the wiring and grounds, we finally swapped in a known-good PCM. The truck fired up and ran like it just rolled off the showroom floor. The original PCM had internal failures that were sending bad signals and causing false sensor readings. It’s a classic case of the symptoms pointing everywhere except the real source.
Direct Solution for Your 1998-1999 Chevrolet 2500 PCM
This is a genuine, used GM Powertrain Control Module, part number 16266645 (interchangeable with 09355699, 16250279, 16258815, and 09366810), that serves as a direct-fit replacement for a wide range of GM trucks and vans. We take the guesswork out of the repair. Before this module ships, we will program it specifically to your vehicle using the Vehicle Identification Number (VIN) you provide. This ensures that it has the correct factory software and the latest updates from GM, making the installation process as smooth as possible.
Symptoms of a Failing PCM:
- ✔ Persistent Check Engine Light (CEL) that won’t clear or returns immediately.
- ✔ Engine stalling, stumbling, or hesitating during acceleration.
- ✔ Harsh or erratic automatic transmission shifting.
- ✔ A sudden, unexplained drop in fuel mileage.
- ✔ The engine cranks but refuses to start.
- ✔ Communication errors with diagnostic scan tools.
- ✔ Multiple, unrelated trouble codes stored in memory.
Why Choose a VIN-Programmed Module?
Simply installing a used PCM from another vehicle will not work. These modules are programmed with vehicle-specific information, including engine and transmission calibrations, emissions standards, and anti-theft (Passlock/VATS) data. Our programming service handles this for you. By flashing the module with your truck’s VIN, we ensure it communicates correctly with all other modules on your vehicle, restoring original factory performance and functionality. This is the most reliable and cost-effective way to get your 1998-1999 Chevrolet 2500 PCM functioning correctly again.
Installation Process
Replacing the PCM is typically a straightforward process. It’s usually located in the engine bay on the driver’s side. After disconnecting the battery, you can unbolt the old module, carefully unplug the wiring harnesses, and install the new one in its place. After installation, you may need to perform a security relearn procedure, which can often be done without special tools. We recommend consulting a service manual for your specific vehicle for detailed instructions.
Frequently Asked Questions
What does a PCM do?
The Powertrain Control Module (PCM) is the central computer that controls your vehicle’s engine and transmission. It takes data from dozens of sensors to manage fuel delivery, spark timing, emissions systems, and transmission shifting to ensure optimal performance, fuel efficiency, and low emissions.
Is this part ready to install?
Yes! This module is programmed to your vehicle’s VIN before it is shipped. This means it has the correct software for your specific make, model, and options. In some cases, a simple security relearn procedure may be required after installation, which you can often do yourself.
Where do I find my VIN?
Your 17-digit Vehicle Identification Number (VIN) can be found on your vehicle’s registration, insurance card, or on a metal plate on the driver’s side of the dashboard, visible through the windshield.
Does this fit vehicles other than a Chevrolet 2500?
Absolutely. This PCM, identified by service number 09355699, fits a wide array of 1998-1999 GM vehicles, including the C/K 1500, 3500, Suburban, Tahoe, Yukon, Express/Savana vans, Cadillac Escalade, and more. Please check the detailed fitment list on this page to confirm compatibility.
Why buy a used OEM module?
A used Original Equipment Manufacturer (OEM) module is a part made by the original vehicle manufacturer. These parts are known for their superior quality, durability, and perfect fitment compared to many aftermarket alternatives. Our modules are sourced from salvaged vehicles and are tested and programmed for reliable service.