Is Your GM Truck or Van Running Rough?
The Powertrain Control Module (PCM), often called the Engine Control Module (ECM), is the electronic brain of your 1998-1999 GMC Savana 2500. It manages critical functions like fuel delivery, ignition timing, transmission shifts, and emissions systems. When this vital component begins to fail, it can cause a wide range of frustrating and often misdiagnosed issues, leaving your vehicle unreliable or completely immobile. This genuine, used GM PCM, part number 9355699, is the definitive solution to restore your vehicle’s performance and dependability.
From the Diagnostic Bay
We once had a 1999 Suburban come into the shop that was driving the owner crazy. It would randomly stall at stoplights and had a persistent Check Engine Light. The owner had already replaced the fuel pump, crank sensor, and a couple of O2 sensors with no luck. After connecting our scan tool, we noticed erratic data readings and intermittent communication loss with the module. The issue wasn’t a faulty sensor, but a failing PCM that was sending bad signals. We installed a VIN-programmed PCM just like this one, and the truck ran perfectly. It’s a classic case of treating the disease, not just the symptoms.
Diagnosing a Faulty 1998-1999 Savana 2500 PCM
A failing engine computer can manifest in several ways. If you’re experiencing any of the following, a faulty PCM could be the culprit. It’s the central command unit, and its failure can mimic problems with many other components, making diagnosis tricky without professional experience.
Common Symptoms of PCM Failure
- ✔ Check Engine Light: The light may be on with communication-related codes (U-codes) or false sensor codes.
- ✔ No-Start Condition: The engine cranks but refuses to start due to lack of spark or fuel injector signal.
- ✔ Stalling or Misfiring: The engine may stall unexpectedly, run rough, or misfire, especially under load.
- ✔ Poor Fuel Economy: Inefficient engine management leads to a noticeable drop in MPG.
- ✔ Harsh or Erratic Shifting: The PCM also controls transmission functions, and failure can cause shifting problems.
- ✔ Failed Emissions Test: Incorrect air/fuel mixture management can lead to an immediate test failure.
The Plug-and-Play Solution
Forget expensive dealership visits and programming fees. This PCM is a tested, reliable unit sourced from a salvaged vehicle. The key benefit is our professional programming service. Before we ship the part, our technicians will flash it with the latest GM software updates, precisely calibrated to your vehicle’s unique Vehicle Identification Number (VIN). This ensures that all parameters match your specific engine, transmission, and options, making installation as simple as possible.
While this module is designed to be a direct replacement, please be aware that on many GM vehicles of this era, a security relearn procedure (also known as a Passlock or VATS relearn) may be required after installation. This procedure pairs the new computer to your vehicle’s anti-theft system and can typically be performed in your driveway without special tools in about 30 minutes.
Guaranteed Compatibility
This PCM, identified by part number 9355699, is a direct replacement for a wide array of GM trucks, vans, and SUVs from the late 1990s. It is compatible with several service numbers, including 09355699, 16266645, 16250279, 16258815, and 09366810. Please verify the part number on your existing module and consult the extensive fitment list to ensure this is the correct component for your vehicle.
Frequently Asked Questions
What do you mean by “programmed to my VIN”?
After you place your order, you will need to provide us with your vehicle’s 17-digit VIN. Our technicians use this number to load the exact factory software and calibrations for your specific vehicle onto the PCM. This ensures it works correctly with your engine, transmission, and other systems right out of the box.
Is this part truly plug-and-play?
For the most part, yes. Once programmed, it will plug directly into your vehicle’s wiring harness. However, you will likely need to perform a security relearn procedure to sync the PCM with your vehicle’s anti-theft system. This is a standard step for this generation of GM vehicles and instructions are widely available online.
How can I be sure my PCM is the problem?
The symptoms listed above are strong indicators of a failing PCM. The most definitive way to know is to have a professional technician diagnose the issue. They can confirm that power and ground signals to the PCM are good and that other components have been ruled out. A PCM is often the last part to check after verifying sensors and wiring.
Where is the PCM located on my 1998-1999 Savana Van?
On the 1998-1999 Savana and Express vans, the PCM is typically located in the engine compartment, on the left-hand (driver’s) side, often near the rear of the engine bay. On pickup trucks and SUVs, it is usually on the driver’s side fender well near the battery.
Is this a new part?
No, this is a high-quality, tested, and fully functional used part that has been sourced from a salvaged vehicle. This provides an affordable and reliable alternative to a costly new unit from the dealership.