Is Your GM Truck or Van Running Rough?
If your 1998-1999 Chevrolet Express, GMC Savana, or other compatible GM truck is experiencing perplexing issues like stalling, no-start conditions, erratic shifting, or a persistent Check Engine Light, the culprit is often a failing Powertrain Control Module (PCM). The PCM is the brain of your vehicle, managing everything from fuel injection and ignition timing to transmission shift points. When it fails, it can cause a cascade of problems that are frustrating and difficult to diagnose. Don’t let a faulty computer keep your reliable workhorse off the road. This is your direct-fit, plug-and-play solution.
From the Diagnostic Bay
I once had a 1999 Suburban in the shop that had its owner chasing ghosts for weeks. The complaint was a random no-start condition. He had already replaced the battery, alternator, and fuel pump based on advice from forums. After hooking up our scanner, we noticed intermittent communication loss with the PCM. A quick wiggle of the main connector on the module caused the engine to stall. A closer look revealed internal corrosion on the PCM board, a common issue on these older work trucks. We installed a VIN-programmed unit just like this one, and the truck fired up instantly and ran perfectly. It’s a reminder that sometimes the most complex symptoms point back to the central computer.
Common Symptoms of a Failing PCM
- ✔ Check Engine Light is on with various communication or sensor codes.
- ✔ Engine cranks but refuses to start.
- ✔ Poor fuel economy and engine performance.
- ✔ Harsh or erratic automatic transmission shifting.
- ✔ Intermittent stalling or misfiring.
- ✔ Failure to pass an emissions test.
- ✔ The anti-theft or security light stays on.
The Simple, Reliable Solution: A VIN-Programmed PCM
Replacing a PCM isn’t just about swapping a box. The new unit needs to be programmed with your vehicle’s specific Vehicle Identification Number (VIN) and the latest software updates from GM to ensure it communicates correctly with all other modules. We handle this critical step for you. When you purchase this 1998-1999 Express 3500 PCM, we will flash it using your VIN before it ships. This means no expensive trips to the dealership for programming. The module arrives at your door ready for installation, saving you time and money.
This quality used ECM, part number 16266645, is a reliable and cost-effective alternative to a new part. It is compatible with a wide range of service numbers, including 09355699, 16250279, and more, fitting dozens of GM trucks and vans from the era. Please verify your part number and consult the detailed fitment list to ensure compatibility.
Installation for Your 1998-1999 Express 3500 PCM
Installation is straightforward for anyone with basic mechanical skills. After disconnecting the battery, you’ll locate the old module in the engine bay, disconnect the electrical connectors, and unbolt it. Install the new module, reconnect everything, and then reconnect the battery. For many of these vehicles, you will need to perform a simple Security Relearn Procedure (also known as a Passlock or VATS relearn) to sync the new PCM with your vehicle’s anti-theft system. This procedure typically involves turning the key to the ‘ON’ position for 10-15 minutes, then ‘OFF’, and repeating the cycle a couple of times. It requires no special tools and instructions are widely available online.
Frequently Asked Questions
Do I need to get this computer programmed?
No. We program the module for you before shipping. Simply provide us with your vehicle’s 17-digit VIN during or after checkout, and we will flash it with the correct GM software for your specific vehicle. It will arrive ready to install.
Is this a new part?
This is a high-quality, tested, and fully functional used part sourced from a salvaged vehicle. It offers a reliable and affordable solution to get your vehicle back in proper working order.
Where is the PCM located on my vehicle?
On most 1998-1999 GM trucks and vans like the Express, Savana, Tahoe, and Suburban, the PCM is located in the engine compartment, typically on the driver’s side fender well or near the battery.
What is the Security Relearn Procedure?
This is a required step to sync the new PCM with your vehicle’s anti-theft system. It’s a simple process that involves cycling the ignition key and waiting for specific intervals. It does not require any special tools and can be done in your driveway in about 30 minutes.
How 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.