Is Your 1998-1999 GM Truck or Van Acting Up?
If you’re dealing with frustrating issues like a no-start condition, erratic engine performance, harsh shifting, or a persistent Check Engine Light that points to the computer, you’ve come to the right place. As a technician with over two decades of experience under the hood, I’ve seen countless GM vehicles from this era sidelined by a failing Powertrain Control Module (PCM). The symptoms can be confusing, often leading to wasted money on replacing perfectly good sensors. This reliable, tested, and VIN-programmed PCM is the straightforward solution to get your vehicle back on the road.
From the Shop Floor: A Real-World Scenario
A customer’s ’99 Express 3500 work van came into my shop last month. It would crank but not start, and the fuel pump wasn’t priming. After checking all the basicsโfuses, relays, and groundsโwe traced it back to a dead PCM. The internal driver for the fuel pump relay had failed, a common issue on these older units after years of heat cycles. A replacement, programmed PCM like this one had him back on the job in under an hour, saving him a costly tow to the dealer and significant downtime.
Why Choose Our 1998-1999 Express 3500 PCM?
This isn’t just a used part pulled from a yard. It’s a complete solution. We take a thoroughly tested, salvaged PCM and professionally flash it with the latest official GM software calibration for your specific vehicle. This ensures all factory-issued performance and drivability corrections are loaded, giving your engine and transmission the precise instructions they need to operate correctly.
- โ VIN-Programmed for You: We flash the module using the Vehicle Identification Number you provide, ensuring it’s a perfect software match for your truck or van’s options.
- โ Latest GM Software: Your PCM will be loaded with the newest calibrations available from General Motors, addressing known bugs and improving performance.
- โ Cost-Effective Repair: Get a reliable, working solution without the high cost of a new module from a dealership.
- โ Broad Compatibility: This module, identified by service number 9355699, is the correct replacement for a wide range of GM vehicles. It directly interchanges with part numbers 09355699, 16266645, 16250279, 16258815, 09366810, and 9366810.
Plug-and-Play Installation Guide
Replacing the PCM on these GM vehicles is a job most DIYers can handle in their own driveway. No dealer visit is required for installation, but a CASE Relearn procedure with a capable scan tool is often necessary after install to prevent a Check Engine Light for code P1336.
- Safety First: Disconnect the negative terminal from your vehicle’s battery.
- Locate the PCM: On most Express/Savana vans and full-size trucks, the PCM is located in the engine compartment, typically on the driver’s side fender well or near the battery.
- Disconnect Connectors: Carefully unclip and remove all electrical connectors from the old PCM. Inspect them for any green corrosion or bent pins before proceeding.
- Swap the Module: Unbolt the old PCM from its bracket and set it aside. Mount your new, pre-programmed PCM in its place.
- Reconnect Everything: Securely plug the electrical connectors into the new module. You should hear a distinct click. Reconnect the negative battery terminal.
- Final Steps: Turn the key to the ‘ON’ position for 10-15 seconds before starting the engine. This allows the system to initialize. The vehicle is now ready to drive.