Restore Your Truck’s Brain and Get Back on the Road
Your 1998-1999 Chevrolet 3500 Pickup is a workhorse, built for tough jobs and reliability. But even the most dependable trucks can suffer from electronic issues. When the Powertrain Control Module (PCM) — the central computer for your engine and transmission — begins to fail, it can cause a host of frustrating and performance-robbing problems. From a persistent check engine light to a truck that won’t start, a faulty PCM can bring your work to a halt. This replacement PCM, part number 16266645, is the definitive solution to restore your truck’s performance and dependability.
This isn’t just a used part pulled from a shelf. We provide a crucial service by programming this module specifically to your truck’s Vehicle Identification Number (VIN). This ensures that the computer has the correct software and calibrations for your specific engine, transmission, and factory options. We flash it with the latest updates from General Motors, so you’re not just replacing a part; you’re getting a component with the most refined software available for your vehicle. This VIN-matching process is essential for proper function and avoids the compatibility headaches that come with generic, unprogrammed modules.
Is Your 1998-1999 Chevrolet 3500 PCM Failing?
A failing Powertrain Control Module can manifest in various ways, often mimicking other sensor or component failures. Proper diagnosis is key, but if you’re experiencing several of the following symptoms, your PCM is a likely culprit.
- ✔ Check Engine Light: An illuminated check engine light with codes related to internal module failure, memory errors, or communication faults (like U-codes).
- ✔ No-Start or Intermittent Start: The engine cranks but refuses to start, or starts unreliably. This can be due to the PCM failing to command spark or fuel injector operation.
- ✔ Poor Engine Performance: Noticeable loss of power, rough idling, stalling, hesitation, or misfires that aren’t resolved by replacing plugs, wires, or coils.
- ✔ Erratic Transmission Shifting: The PCM also controls the 4L80E automatic transmission. A faulty module can cause harsh shifts, delayed shifting, or getting stuck in one gear (limp mode).
- ✔ Reduced Fuel Economy: If the PCM isn’t correctly managing the air/fuel mixture and ignition timing, your truck’s fuel efficiency can drop significantly.
- ✔ Communication Issues: Your diagnostic scan tool may be unable to communicate with the PCM, a clear sign of an internal failure.
The Simple, Reliable Solution
Replacing your PCM doesn’t have to be a complicated or expensive trip to the dealership. Our process is designed for the DIY mechanic and professional alike. Once you purchase the module, simply provide us with your truck’s VIN. Our technicians will program the unit, ensuring it’s a perfect match. Installation is straightforward:
- Disconnect the Battery: Always start by disconnecting the negative battery terminal for safety.
- Locate and Remove: The PCM is typically located in the engine compartment on the driver’s side. Unplug the color-coded electrical connectors and unbolt the module from its bracket.
- Install the Replacement: Bolt the new, programmed PCM into place and securely reconnect the wiring harnesses.
- Perform Security Relearn: After reconnecting the battery, you will need to perform a simple security relearn procedure (often called VATS or Passlock). This syncs the new PCM with your truck’s anti-theft system and can be done in your driveway with just the ignition key. The process typically takes about 30 minutes.
This module is a direct replacement for multiple part numbers, including 09355699, 16266645, 9355699, 16250279, 16258815, 09366810, and 9366810. It fits a wide range of GM trucks and vans from the era, as detailed in our fitment list. Verify your part number or vehicle application to ensure a perfect match.
Frequently Asked Questions
How do I provide my VIN for programming?
After you complete your purchase, you can add your 17-digit VIN to the order notes or send it to us in a message. We cannot ship the module until we have your VIN to program it.
Is this a new computer?
No, this is a high-quality, tested, and fully functional used OEM computer sourced from a salvaged vehicle. This provides OEM reliability at a fraction of the cost of a new unit.
Will I need to take my truck to a dealer after installation?
No. Because we pre-program the PCM to your VIN, you will not need a dealer’s scan tool. The only step required after physical installation is the security relearn procedure, which you can do yourself with your key.
What is the security relearn procedure?
It’s a simple process. You’ll turn the key to the ‘ON’ position for 10 minutes, then ‘OFF’ for 10 seconds. You repeat this cycle three times. On the third cycle, the truck should start, and the security system will be synced to the new PCM.
How can I be sure the PCM is the problem?
While the symptoms listed are strong indicators of PCM failure, it’s always best to perform a thorough diagnosis. Ensure that power and ground supplies to the PCM are good and that other components have been ruled out. This part will only fix your issue if the original PCM is indeed faulty.
Does this fit vehicles other than the Chevy 3500?
Yes. This PCM, identified by service number 09355699, fits a wide variety of 1998-1999 GM trucks and vans, including the Suburban, Tahoe, Yukon, Express, Savana, and various pickup models. Please check the detailed fitment list to confirm compatibility with your specific vehicle.