Is Your GM Truck or Van Running Rough?
If your 1998-1999 GMC 3500, Chevrolet Silverado, Tahoe, or another GM vehicle from this era is suffering from erratic behavior like stalling, poor fuel economy, harsh shifting, or a persistent Check Engine Light, a failing Powertrain Control Module (PCM) is often the culprit. As the central computer for your engine and transmission, the PCM’s health is critical for performance, reliability, and efficiency. When it starts to fail, it can cause a cascade of frustrating and difficult-to-diagnose issues, leaving you stranded or with an unreliable vehicle.
Common Symptoms of a Failing PCM
- ✔ Persistent Check Engine Light (CEL) with various trouble codes.
- ✔ Engine stalling, stuttering, or misfiring, especially under load.
- ✔ Noticeable decrease in fuel economy.
- ✔ Harsh, erratic, or delayed transmission shifting.
- ✔ Complete no-start or intermittent starting problems.
- ✔ Failure to communicate with a diagnostic scan tool.
- ✔ Other modules in the vehicle reporting a loss of communication with the PCM.
From the Diagnostic Bay
We had a 1999 Chevy Suburban come in that had its owner chasing ghosts for weeks. The symptoms were all over the place: random stalling, transmission wouldn’t shift out of first gear on some days, and a flickering check engine light. The owner had already replaced the fuel pump and ignition coil based on advice from forums. He was convinced his PCM was fried. Before swapping the module, we did a full diagnostic check, which included inspecting the main wiring harness and grounds. Tucked away on the frame rail under the driver’s door was a main ground strap that was corroded and barely making contact. We cleaned the connection point, re-secured the ground, and every single issue disappeared. It’s a powerful reminder: always check your grounds before condemning an expensive component! A bad ground can mimic a bad PCM perfectly.
Your Direct-Fit Programmed Solution: The 1998-1999 GMC 3500 PCM
Don’t let a faulty computer keep your truck off the road. This is a genuine, used OEM Powertrain Control Module, part number 09355699, that has been thoroughly tested and is ready for installation. The key to a successful repair is the programming, and we handle that for you. Using the Vehicle Identification Number (VIN) you provide, we flash the module with the latest, most up-to-date software directly from GM for your specific vehicle configuration. This critical step ensures that the PCM communicates correctly with your engine, transmission, and all other vehicle systems, eliminating the need for an expensive trip to the dealership.
This is not a generic, one-size-fits-all part. It is a precisely configured component that restores the original functionality and performance of your vehicle. The process is simple: place your order, provide us with your VIN, and we’ll ship a module that is programmed and ready to be installed right out of the box. This module is a direct replacement for several part numbers, including 16266645, 9355699, 16250279, 16258815, 09366810, and 9366810.
Frequently Asked Questions
Why do you need my VIN?
Your vehicle’s VIN (Vehicle Identification Number) is essential because it allows us to program the PCM with the exact software and calibrations for your specific engine, transmission, and options package. This ensures seamless integration and proper function, avoiding compatibility issues.
Is this part difficult to install?
For most of the listed GM trucks and vans, the PCM is located in the engine bay and is held in by a few bolts and has several large electrical connectors. Installation is typically straightforward for someone with basic mechanical skills. The most important step is to disconnect the vehicle’s battery before starting the replacement to prevent electrical damage.
Will this fix my check engine light?
If the check engine light is on due to an internal failure of your original PCM, then yes, this replacement module should resolve the issue and allow the light to be cleared. However, if the light is on due to a problem with a sensor, wiring, or another component, that underlying issue will still need to be repaired.
What’s the difference between a PCM and an ECM?
ECM stands for Engine Control Module, while PCM stands for Powertrain Control Module. In many vehicles from this era, like your GM truck, the PCM is an integrated unit that controls both the engine and the transmission functions. The terms are often used interchangeably, but PCM is the more accurate term for this specific part.
Is any other programming needed after installation?
After installing this VIN-programmed PCM, you may need to perform a CASE (Crankshaft Angle Sensor Error) relearn procedure, also known as a crank relearn. This can be done with a capable bidirectional scan tool and is necessary for the computer to learn the precise position of the crankshaft, preventing potential misfire codes. Some vehicles may also require a security relearn, which can often be done without special tools by cycling the key in the ignition.