Is your 1998 or 1999 Chevrolet Express or GMC Savana Van running poorly, stalling, or refusing to start? The Powertrain Control Module (PCM), the central computer for your engine and transmission, is often the culprit. This vital component manages everything from fuel delivery and spark timing to transmission shift points and emissions controls. When it fails, it can cause a wide range of frustrating and difficult-to-diagnose issues. Don’t let a faulty computer keep your workhorse off the road. We offer a reliable, cost-effective solution with this genuine, used OEM PCM, fully programmed to your vehicle’s specific Vehicle Identification Number (VIN).
From the Diagnostic Bay
We had a 1999 Express 3500 in the shop that was driving the owner crazy. It would run fine for a week, then suddenly start stalling at traffic lights and shifting hard into second gear. The check engine light was intermittent. The owner had already replaced the fuel filter and spark plugs with no improvement. After hooking up our professional scan tool, we noticed intermittent communication loss with the PCM. A quick check of the main power and ground wires to the module showed they were solid. The issue was internal to the PCM; the board was failing under thermal stress. Replacing it with a VIN-programmed unit like this one solved all the issues instantly, getting the van back to work the same day.
Diagnosing a Faulty 1998-1999 Express 3500 PCM
A failing PCM can mimic many other mechanical problems, making diagnosis tricky. However, there are several key indicators that point towards the engine computer. If your van is experiencing one or more of the symptoms below, a faulty PCM is a likely cause. This pre-programmed 1998-1999 Express 3500 PCM is the definitive solution to restore your vehicle’s factory performance and reliability. We take the guesswork out of the repair by flashing the module with the latest GM software updates specific to your VIN, ensuring it works seamlessly with your van’s other electronic systems right out of the box.
Common Symptoms of PCM Failure
- ✔ Check Engine Light: The light is illuminated, often with communication error codes (U-codes) or multiple random sensor codes.
- ✔ No-Start Condition: The engine cranks but will not start, and you’ve confirmed spark and fuel pressure are present.
- ✔ Stalling and Rough Idle: The engine may stall unexpectedly while driving or idle erratically.
- ✔ Poor Fuel Economy: A sudden and unexplained drop in MPG can be caused by incorrect fuel and air calculations from a failing PCM.
- ✔ Erratic Transmission Shifting: The PCM controls transmission solenoids, and a failure can lead to harsh shifts, delayed engagement, or getting stuck in one gear.
- ✔ Failed Emissions Test: The PCM directly controls the emissions systems, and a fault will almost certainly cause a test failure.
This unit is a genuine used OEM part, sourced from a salvaged vehicle and rigorously tested for functionality. By providing us with your VIN upon purchase, you ensure that the module you receive is a plug-and-play solution. This eliminates the need for expensive programming services at a dealership. The installation is straightforward for any DIY mechanic, typically involving disconnecting the battery, unplugging the old module, and installing the new one. A security relearn procedure may be required after installation, which can often be done without special tools.
Frequently Asked Questions
Do I need to have this PCM programmed?
No. We handle all the programming for you before shipping. Simply provide your vehicle’s VIN during or after checkout, and the module will arrive ready for installation.
What is the difference between a PCM, ECM, and ECU?
These terms are often used interchangeably. ECM (Engine Control Module) typically controls only the engine. PCM (Powertrain Control Module) controls both the engine and transmission. For your 1998-1999 Express Van, this module functions as a PCM.
Is this a difficult part to install?
Installation is generally straightforward. It involves disconnecting the vehicle’s battery, locating the old PCM in the engine bay, unplugging its electrical connectors, and swapping in the replacement. Basic hand tools are all that’s required.
Will I need to perform a security relearn after installation?
Yes, it is very likely you will need to perform a GM Passlock/VATS security relearn procedure. This process pairs the new PCM to your vehicle’s anti-theft system and can typically be done in your driveway without any special tools. Instructions are widely available online.
How do I find my vehicle’s VIN?
Your 17-digit VIN can be found on your vehicle’s registration, insurance card, or on a placard on the driver’s side dashboard visible through the windshield.