Is Your GM Truck or Van Acting Up?
If your late-90s Chevy Express, Suburban, or GMC Sierra is suddenly stalling, shifting erratically, or refusing to start, the problem might not be what you think. After 20+ years in the shop, I’ve seen countless owners replace nearly every ignition component chasing a persistent misfire or a random no-start, only to find the root cause was the Powertrain Control Module (PCM) all along. These modules are the brains of your vehicle, and when they fail, the symptoms can be confusing and frustrating.
The Smart Solution: A VIN-Programmed PCM
This isn’t just a used part; it’s a complete, ready-to-install solution. We take a genuine, tested PCM and flash it with the latest official GM software updates specifically for your vehicle. All we need is your VIN. This process ensures the computer has the correct calibration for your engine, transmission, and options, eliminating the guesswork and the need for an expensive trip to the dealership for programming.
From the Shop Floor: A Real-World Diagnosis
“A customer’s ’99 Suburban came in last week with a dead misfire on cylinder 3. He had already replaced the plug, wire, distributor cap, and rotor. He even swapped the fuel injector. Nothing worked. After confirming good compression and spark, we suspected the PCM. On these older GM Vortec engines, it’s common for the injector driver circuit inside the PCM to fail, cutting fuel to a single cylinder. We installed one of our VIN-programmed modules, and the truck ran perfectly. It’s a diagnosis I’ve made hundreds of times, saving customers time and money on unnecessary parts.”
Symptoms of a Failing 1998-1999 Express 1500 PCM
If you’re experiencing any of the following, your PCM could be the culprit:
- ✔ Check Engine Light is on with various communication or sensor codes.
- ✔ Vehicle has a no-start or hard-start condition.
- ✔ Harsh or erratic automatic transmission shifting.
- ✔ Noticeable drop in fuel economy.
- ✔ Engine stalls for no apparent reason.
- ✔ Persistent misfires even after a full ignition system service.
Plug-and-Play Installation: No Dealer Visit Required
Installing your programmed PCM is a straightforward job you can do in your own driveway. Follow these steps for a successful replacement:
- Safety First: Disconnect the negative terminal from your vehicle’s battery.
- Locate the PCM: On most of these trucks and vans, the PCM is located in the engine compartment, typically on the driver’s side fender well or firewall.
- Disconnect the Connectors: Carefully unclip and remove the large wiring harness connectors from the old module. Inspect the pins for any corrosion or damage before proceeding.
- Remove the Old Module: Unbolt the old PCM from its mounting bracket.
- Install the New Module: Bolt your new, pre-programmed PCM into place.
- Reconnect Everything: Firmly plug the wiring harness connectors into the new PCM until they click. Reconnect your negative battery terminal.
- Final Step: In some cases, a security relearn procedure may be necessary. This simple procedure can be done without special tools and instructions are readily available online for your specific model.
Guaranteed Compatibility
This module is a direct replacement for a wide range of GM trucks and vans. It is compatible with multiple service numbers, including: 09355699, 16266645, 9355699, 16250279, 16258815, 09366810, and 9366810. Please verify your part number or use the detailed fitment list to confirm this is the correct part for your vehicle.