Get Your GM Truck or Van Running Right Again
If you’re dealing with frustrating engine problems on your 1998-1999 GM vehicle—erratic idling, stalling, a persistent check engine light, or even a no-start condition—a failing Powertrain Control Module (PCM) is often the culprit. As the central computer for your engine and transmission, its health is critical. This isn’t just a replacement part; it’s a direct solution, a tested, used OEM PCM that arrives at your door programmed with the latest GM software updates, specifically matched to your vehicle’s VIN.
Case Study: The Ghost in the Machine
I once had a 1999 Express 3500 work van in my bay that was driving the owner crazy. It would run perfectly for days, then suddenly stall at a stoplight or refuse to start after a delivery. There were no consistent trouble codes, just a random collection of communication errors that would come and go. We checked grounds, wiring, and sensors for weeks. On a hunch, I swapped in a known-good PCM. The problems vanished instantly. The original module had an internal hairline fracture on the circuit board that would separate when it got hot, cutting power. This pre-programmed 1998-1999 Express 3500 PCM is the exact fix for these kinds of phantom issues that plague so many of these otherwise reliable workhorses.
Is Your GM Truck or Van Showing These Signs?
A faulty PCM can manifest in numerous ways. If you’re experiencing any of the following, this module is the likely solution your vehicle needs. Proper diagnosis is always recommended, but these are classic symptoms I’ve seen hundreds of time in my shop.
- ✔ Check Engine Light is on with codes for internal module failure (e.g., P0601, P0605).
- ✔ Vehicle refuses to start or has trouble starting.
- ✔ Poor fuel economy and engine performance.
- ✔ Harsh or erratic automatic transmission shifting.
- ✔ Intermittent stalling or rough idling for no apparent reason.
- ✔ Failure to communicate with a diagnostic scan tool.
The Power of VIN Programming
Why is VIN programming so important? On these GM vehicles, the PCM is tied directly to the specific options and security system of your truck or van. Buying a generic module from a salvage yard without programming will result in a no-start condition due to the anti-theft system. Our process eliminates that headache. By providing your Vehicle Identification Number (VIN) at checkout, you receive a 1998-1999 Express 3500 PCM that is truly ready for installation. We flash it with the correct calibration and the most current GM software, which often corrects drivability issues the vehicle had even when it was new.
Your Straightforward Installation Guide
Replacing the PCM is a manageable job for a DIY enthusiast. With our pre-programmed module, you skip the most difficult step—the programming. Just follow these general steps to get back on the road.
- Safety First: Always disconnect the negative terminal from your vehicle’s battery and wait at least 10 minutes for the system capacitors to discharge.
- Locate the PCM: On most of these trucks and vans (like the Express, Savana, Tahoe, and Suburban), the PCM is located in the engine compartment, typically on the driver’s side near the fender or firewall.
- Disconnect Connectors: Carefully unclip and remove the electrical harness connectors from the old PCM. Inspect them for any corrosion or damage.
- Swap the Module: Unbolt and remove the old PCM. Mount the new, programmed PCM in its place and secure it.
- Reconnect Everything: Firmly plug the harness connectors into the new PCM. Reconnect the negative battery terminal.
- Perform Security Relearn: This is a critical step. You must perform the vehicle’s anti-theft relearn procedure. This typically involves turning the key to the ‘ON’ position for 10-15 minutes, then ‘OFF’, and repeating two more times. Your vehicle will not start until this is completed successfully. Consult a service manual for the exact procedure for your model.
Verified Compatibility for Your Vehicle
This module, identified by part number 09355699, is a direct replacement for a wide range of GM vehicles. It also interchanges with part numbers 16266645, 16250279, 16258815, and 09366810. Please verify your vehicle is on this list and that your original module carries one of these compatible part numbers.
This part fits numerous 1998-1999 models, including but not limited to:
- ✔ Chevrolet: Express/Savana 1500/2500/3500 Vans, C/K 1500/2500/3500 Pickups, Suburban, Tahoe, Astro, Blazer S10, S10 Pickup
- ✔ GMC: Savana/Express Vans, Sierra C/K 1500/2500/3500 Pickups, Yukon, Safari, Jimmy S15, Sonoma S15
- ✔ Cadillac: Escalade (1999)
- ✔ Oldsmobile: Bravada (1998)
- ✔ Isuzu: Hombre (1998)
Note: Compatibility depends on specific options like engine size and build date. Matching the ID number 09355699 is the best way to ensure a perfect fit.
Frequently Asked Questions
Frequently Asked Questions
What information do you need to program this PCM?
We require your 17-digit Vehicle Identification Number (VIN) to flash the module with the correct software and calibrations for your specific vehicle. Please provide it during or after checkout.
Is this part truly plug-and-play?
The module is pre-programmed, which handles the most complex part. However, you MUST perform a security relearn procedure after installation. This procedure syncs the new PCM with your vehicle’s anti-theft system and does not require any special tools.
Where is the PCM located on my 1999 Chevy Express Van?
On the 1998-1999 Express and Savana vans, the PCM is typically located in the engine compartment, mounted on the left-hand (driver’s side) rear of the engine compartment.
Is this a new computer?
No, this is a thoroughly tested, used OEM (Original Equipment Manufacturer) computer sourced from a salvaged vehicle. This ensures OEM quality and reliability at a great value.
My original part number is 16266645. Will this work?
Yes. This PCM, part number 09355699, is a direct interchange for several part numbers, including 16266645. As long as your vehicle is on the compatibility list, this module will function correctly.