If your 1998-1999 Chevrolet Express 3500 Van is suddenly giving you trouble—stalling at intersections, shifting erratically, or refusing to start altogether—the problem often points directly to a failing Powertrain Control Module (PCM). As the brain of your vehicle’s engine and transmission, when the PCM goes, it can create a host of confusing and frustrating issues. This isn’t just an inconvenience; for a workhorse like the Express Van, it’s downtime that costs you money and peace of mind.
We offer a dependable and straightforward solution: a genuine, used OEM Powertrain Control Module, service number 16258815, that is professionally programmed to your van’s specific Vehicle Identification Number (VIN). This critical step ensures that the computer has the latest GM software updates and communicates perfectly with your vehicle’s systems right out of the box, eliminating the need for an expensive trip to the dealership for programming. Get your reliable van back on the road and back to work with a part you can trust.
A Technician’s Notebook
I remember a fleet customer who brought in a ’99 Express 3500 that was a diagnostic nightmare. It had a random misfire that wouldn’t set a specific cylinder code, harsh 1-2 shifts, and would occasionally stall when coming to a stop. The previous shop had already replaced plugs, wires, and the fuel filter. After checking all the basics, my scanner showed a P0601 ‘Internal Control Module Memory Check Sum Error’. These older GM PCMs, especially the ‘black box’ style, are known for internal solder joint failures and board issues after decades of heat cycles. Swapping in a VIN-programmed PCM like this one solved all three problems instantly. It’s often the foundational fix that other repairs can’t solve.
Is Your Van Showing These Signs of PCM Failure?
A faulty PCM can manifest in various ways. If you’re experiencing any of the following, a replacement 1998-1999 Express 3500 PCM is likely the solution you need. Look out for:
- ✔ Check Engine Light is on with no clear cause.
- ✔ Stored diagnostic trouble codes (DTCs) like P0601, P0604, or P0606 pointing to internal module failure.
- ✔ The engine cranks but refuses to start.
- ✔ Unexplained drops in fuel economy.
- ✔ Harsh or erratic automatic transmission shifting.
- ✔ The vehicle stalls intermittently, especially when warm or at idle.
- ✔ Failure to pass an emissions inspection.
A Straightforward Guide to Installation
Replacing the PCM on these vans is a job most DIYers can handle with basic tools. Our pre-programming service saves you the hardest part. Here’s a general guide:
- Safety First: Always disconnect the negative terminal from your vehicle’s battery before starting any electrical work.
- Locate the PCM: On most 1998-1999 Express and Savana vans, the PCM is located in the engine compartment, typically on the driver’s side, mounted near the firewall or inner fender.
- Disconnect the Connectors: Carefully unlatch and remove the wiring harness connectors. These connectors have locking tabs; be gentle to avoid breaking them. Note their color and orientation.
- Remove the Old Module: Unbolt the PCM from its mounting bracket. It’s usually held in by a few bolts or nuts.
- Install the New Module: Mount your replacement 1998-1999 Express 3500 PCM onto the bracket and securely fasten it.
- Reconnect Everything: Plug the wiring harnesses back into the correct slots on the new PCM. Ensure they click into place and are fully seated. Reconnect the negative battery terminal.
- Perform Security Relearn (If Necessary): In some cases, a security relearn procedure may be required for the vehicle to start. This typically involves turning the key to the ‘ON’ position for 10-15 minutes, then off, and repeating two more times. Consult your vehicle’s service manual for the exact procedure.
Verified Vehicle Compatibility
This module is a direct replacement for service number 16258815 and interchanges with several other part numbers. It is guaranteed to fit the following vehicles with matching ID 9355699. Please verify your original part number or ID before ordering.
Fits a wide range of 1998-1999 GM Trucks, Vans, and SUVs, including:
- Chevrolet Express / GMC Savana Van (1500, 2500, 3500)
- Chevrolet / GMC Pickup (1500, 2500, 3500)
- Chevrolet Suburban / GMC Yukon XL (1500, 2500)
- Chevrolet Tahoe / GMC Yukon
- Cadillac Escalade
- Chevrolet Astro / GMC Safari
- Chevrolet S10 / GMC Sonoma
- Chevrolet Blazer / GMC Jimmy
- Oldsmobile Bravada
- Isuzu Hombre
This module is compatible with multiple engine options including the 4.3L V6, 5.0L V8, and 5.7L V8. This is a tested, used part from a salvaged vehicle, ready to restore your vehicle’s operation.
Frequently Asked Questions
What information do you need to program the PCM?
After you complete your purchase, we will need the 17-digit Vehicle Identification Number (VIN) from your van. You can typically find this on your driver’s side dashboard (visible through the windshield) or on the door jamb sticker.
Is this a new part?
No, this is a high-quality, tested used OEM part that was carefully removed from a salvaged vehicle. We ensure it is fully functional before programming and shipping.
Will I need to do anything else after installing this 1998-1999 Express 3500 PCM?
Because we program it to your VIN, it should be a plug-and-play installation in most cases. Some GM vehicles of this era may require a simple security or CASE relearn procedure, which can often be done without special tools.
How do I know if the PCM is really the problem?
Common symptoms include a no-start condition, erratic shifting, poor performance, and specific diagnostic codes like P0601. While these are strong indicators, we always recommend a proper diagnosis by a qualified mechanic to confirm the PCM is the point of failure.
What does ‘programmed with the newest updates’ mean?
Over the years, manufacturers like GM release software updates to fix bugs, improve transmission shifting, and enhance engine performance. We flash the module with the latest official GM calibration available for your specific VIN, ensuring optimal operation.