Is Your Late 90s GM Truck or Van Running Rough?
If you’re dealing with frustrating engine problems in your 1998 or 1999 Chevrolet, GMC, or Cadillac, a failing Powertrain Control Module (PCM) is often the hidden culprit. The PCM is the electronic brain of your vehicle, managing everything from fuel injection and ignition timing to transmission shifting and emissions controls. When it starts to fail, it can create a cascade of issues that are difficult to diagnose, leaving you stranded or with a vehicle that’s unreliable and inefficient. This isn’t just an inconvenience; it’s a critical failure that affects performance, fuel economy, and safety.
From the Diagnostic Bay
I once had a 1999 Chevy Suburban come into the shop that had its owner completely stumped. He’d replaced the spark plugs, wires, cap, rotor, and even the fuel pump, but it still had a persistent misfire and terrible hesitation under load. The check engine light was on, but the codes were all over the place—misfire, lean condition, O2 sensor faults. After hours of chasing ghosts, we hooked up a scope to the injector drivers at the PCM. Sure enough, the signal for cylinder 3 was erratic. We swapped in a known-good, programmed PCM, and the truck immediately purred like a kitten. It’s a classic case of a failing internal driver in the computer, a problem no amount of new sensors can fix. This highlights why starting with the vehicle’s central computer is sometimes the most direct path to a solution.
Symptoms of a Failing PCM
- ✔ Check Engine Light: The light is on, and you may have codes related to sensors, misfires, or communication errors (like P0601 – Internal Control Module Memory Check Sum Error).
- ✔ Poor Engine Performance: Your truck may experience rough idling, stalling, hesitation during acceleration, or a noticeable loss of power.
- ✔ Reduced Fuel Economy: A faulty PCM can’t properly manage the air-fuel mixture, leading to your engine burning more gas than necessary.
- ✔ Erratic Transmission Shifting: The PCM also controls the transmission, so you might notice harsh shifts, delayed engagement, or getting stuck in one gear (limp mode).
- ✔ No-Start Condition: In severe cases, the PCM can fail completely, preventing the engine from starting at all, even if the battery and starter are good.
- ✔ Failure to Pass Emissions: An improperly functioning module will prevent the vehicle’s systems from running their self-checks, resulting in an automatic emissions test failure.
The Direct-Fit, Programmed Solution for Your Vehicle
This isn’t just a generic, off-the-shelf computer. This is a genuine, used OEM Powertrain Control Module, part number 09355699, that we program specifically for your vehicle before it ships. By providing us with your Vehicle Identification Number (VIN), we flash the module with the latest, most stable software updates directly from GM. This ensures that your 1998-1999 Chevrolet 2500 Pickup PCM arrives ready to install, restoring the precise factory settings your truck needs to run its best. You get a reliable part that communicates flawlessly with all other modules in your vehicle, eliminating the guesswork and the need for an expensive trip to a dealership for programming.
Guaranteed Compatibility
This electronic control module is a direct replacement for a wide range of popular GM trucks, vans, and SUVs from the 1998-1999 era. It is fully compatible with the following part numbers:
- ✔ 09355699
- ✔ 16266645
- ✔ 9355699
- ✔ 16250279
- ✔ 16258815
- ✔ 09366810
- ✔ 9366810
Please verify your original part number or consult the extensive fitment list provided to ensure this is the correct module for your specific vehicle and options. Installing the correct 1998-1999 Chevrolet 2500 Pickup PCM is critical for proper function.
Frequently Asked Questions
Do I need to do any programming after I receive this PCM?
No. We program the PCM to your vehicle’s VIN before shipping. However, on many GM vehicles of this era, you will need to perform a simple security relearn procedure after installation, which can typically be done without special tools. This syncs the new PCM with your vehicle’s anti-theft system.
How do I provide my VIN number?
After you complete your purchase, simply send us a message with your 17-digit VIN. We cannot ship your part until we receive this information, as the programming is specific to your vehicle.
Is this a new part?
This is a high-quality, tested, used OEM part sourced from a salvaged vehicle. Each unit is inspected and verified to be fully functional before being programmed and shipped.
What if my original part number is slightly different but on the compatibility list?
If your part number is listed as a compatible replacement (e.g., 16266645), this module will function correctly in your vehicle once programmed to your VIN. GM often supersedes part numbers over time.
Will this fix my check engine light?
If the check engine light and associated codes are caused by a faulty PCM, then yes, this part will resolve the issue. It’s crucial to ensure your vehicle’s problem has been properly diagnosed before ordering.