Is Your GM Truck or Van Running Rough? The PCM Might Be the Culprit.
If your 1998-1999 Chevrolet Express, GMC Savana, or other compatible GM vehicle is suffering from mysterious engine problems, a failing Powertrain Control Module (PCM) is a likely cause. The PCM is the electronic brain of your vehicle, managing everything from fuel injection and ignition timing to transmission shifting and emissions control. When it starts to fail, it can create a cascade of frustrating and difficult-to-diagnose issues, leaving you stranded or dealing with poor performance and fuel economy.
This genuine, used GM PCM, part number 09355699, is the reliable and cost-effective solution to restore your vehicle’s factory performance. We take the guesswork out of the repair by programming the module specifically for your vehicle using your VIN. This ensures that all factory settings, security information, and the latest GM software updates are loaded before it ever leaves our facility. The result is a component that is ready for installation, getting you back on the road quickly and confidently.
From the Diagnostic Bay
We had a 1999 Chevy Suburban come in that had its owner chasing ghosts for weeks. The symptoms were intermittent stalling at stoplights and a random cylinder misfire code (P0300) that would come and go. The owner had already replaced the spark plugs, wires, cap, rotor, and even the fuel pump. After hours of diagnostics, we found that the PCM was intermittently failing to command the ignition coil to fire under certain load conditions. Swapping in a VIN-programmed PCM like this one solved the problem instantly. It’s a classic example of how a faulty module can mimic a dozen other mechanical issues.
Diagnosing a Faulty 1998-1999 Express 2500 PCM
A failing engine computer can manifest in numerous ways. If you’re experiencing any of the following, it’s time to consider your PCM as the root cause. This module is the central command for your powertrain, and its failure can impact multiple systems at once.
Common Symptoms of PCM Failure:
- ✔ Check Engine Light: An illuminated or flashing Check Engine Light is one of the most common signs. Codes may point to specific sensors, but the PCM itself could be the underlying issue.
- ✔ Engine Stalling or Misfiring: The engine may stall unexpectedly, run rough, or misfire, especially under load.
- ✔ No-Start Condition: The engine cranks but refuses to start, often due to the PCM not commanding fuel or spark.
- ✔ Poor Fuel Economy: A sudden and unexplained drop in MPG can be caused by the PCM failing to properly regulate the air-fuel mixture.
- ✔ Harsh or Failed Transmission Shifting: The PCM also controls transmission functions, and a fault can lead to erratic shifting, getting stuck in a gear, or a complete failure to shift.
- ✔ Communication Errors: Your mechanic’s scan tool may be unable to communicate with the PCM, a definitive sign of a major internal fault.
A Simple, Reliable Solution
Don’t let a bad PCM keep your work van or family truck off the road. This unit is a direct replacement for a wide range of 1998-1999 GM trucks and vans. It is compatible with multiple service numbers, including 16266645, 9355699, 16250279, 16258815, 09366810, and 9366810. By providing us with your VIN upon purchase, you ensure that you receive a module that is correctly configured for your vehicle’s specific engine, transmission, and options. This critical programming step prevents compatibility issues and ensures a smooth installation process. While the unit itself is plug-and-play, some vehicles may require a security or CASE (Crankshaft Angle Sensor Error) relearn procedure with a capable scan tool after installation to finalize the communication between the new PCM and the rest of the vehicle’s modules.
Frequently Asked Questions
Why do you need my VIN?
Your Vehicle Identification Number (VIN) allows us to program the PCM with the exact software and calibrations for your specific engine, transmission, and options package. This ensures perfect compatibility and function, just like the original module from the factory.
Is this a plug-and-play part?
Yes, the module is programmed to be plug-and-play. However, on many GM vehicles of this era, a security relearn procedure and a CASE relearn may be required after installation. This can typically be done by a qualified mechanic with a professional-grade scan tool.
Is this a new or used part?
This is a high-quality, tested, and guaranteed used OEM part sourced from a salvaged vehicle. We inspect each unit to ensure it’s fully functional before programming and shipping.
Will this fix my check engine light?
If the check engine light and associated codes are caused by a faulty PCM, then this replacement part will resolve the issue. It’s crucial to have a proper diagnosis to confirm the PCM is the root cause before ordering.
What tools are needed for installation?
Basic hand tools, such as a socket set, are typically all that’s needed to physically swap the module. Always disconnect the battery before beginning the installation. A professional scan tool may be needed for post-installation procedures like a CASE relearn.