Restore Your Truck’s Brain and Get Back on the Road
Is your trusty Chevy or GMC truck suddenly running rough, refusing to start, or throwing a stubborn Check Engine Light? Before you start throwing expensive parts at it, the problem might be its central computer. The Powertrain Control Module (PCM), or ECM, is the brain of your vehicle’s operation, managing everything from fuel delivery and spark timing to transmission shifting. When it fails, it can cause a host of frustrating and hard-to-diagnose issues. This is a reliable, tested, and ready-to-install solution for your 1998-1999 Chevrolet 2500 Pickup and many other GM vehicles of the era.
We take the guesswork and high cost out of the repair. Unlike a generic part from the auto parts store, this genuine used PCM is professionally programmed to your truck’s specific Vehicle Identification Number (VIN) before it ships. This means it arrives loaded with the latest GM software updates for your exact configuration, ensuring optimal performance and fuel economy. You get a part that’s ready to install right out of the box, saving you a costly trip to the dealership for programming.
A Technician’s Notebook
I remember a 1999 GMC Yukon that came into the bay on a tow truck. The owner had already replaced the fuel pump and ignition coil, but it still wouldn’t start—it would only crank. The scanner was throwing an intermittent P0601 (Internal Control Module Memory Check Sum Error). These internal PCM faults are tricky because they don’t always point to a specific sensor. After verifying power and ground to the computer were solid, we knew the PCM itself was the culprit. We installed a VIN-programmed module just like this one, performed the security relearn, and the truck fired up on the first try. It’s a classic failure on these GMT400 platforms, and a pre-programmed module is the most efficient fix.
Is Your Truck Showing These Symptoms?
A failing PCM can manifest in many ways. If you’re experiencing any of the following, this module is very likely the solution you need:
- ✔ Check Engine Light is on with codes like P0601, P0604, or P0606.
- ✔ The engine cranks but refuses to start.
- ✔ Harsh or erratic automatic transmission shifting.
- ✔ Unexplained drop in fuel economy.
- ✔ Stalling, rough idling, or engine misfires.
- ✔ Communication errors with your scan tool.
A Straightforward Guide to Installation
Replacing the 1998-1999 Chevrolet 2500 PCM is a job most DIYers can handle in their own driveway. While a security relearn procedure is required after installation, it doesn’t require special tools. Always consult a repair manual for your specific vehicle, but here are the general steps:
- Safety First: Disconnect the negative terminal from your vehicle’s battery to prevent any electrical shorts.
- Locate the PCM: On most of these trucks and SUVs, the PCM is located in the engine compartment on the driver’s side, near the fender or firewall.
- Disconnect Connectors: Carefully unclip the wiring harness connectors from the old PCM. These connectors have locking tabs; be gentle to avoid breaking them.
- Remove the Old Module: Unbolt the PCM from its mounting bracket and remove it from the vehicle.
- Install the New PCM: Mount your new, pre-programmed PCM onto the bracket and securely re-attach the wiring harness connectors. Ensure they click into place.
- Reconnect Battery: Re-attach the negative battery terminal.
- Perform Security Relearn (Passlock/VATS): This is a critical step. Turn the key to the ‘ON’ position (don’t start) for 10-15 minutes, or until the ‘Security’ light stops flashing and turns off. Turn the key off for 10 seconds. Repeat this cycle two more times (for a total of three cycles). The vehicle should now start and run with the new PCM.
Verified Vehicle Compatibility
This module, identified by service number 9355699, is a direct replacement for a wide range of GM vehicles. It is also an exact replacement for part numbers 16266645, 16250279, 16258815, and 09366810. Please match your part number or verify your vehicle is on the list below:
- CHEVROLET 1500/2500/3500 PICKUP (1998-1999)
- GMC 1500/2500/3500 PICKUP (1998-1999)
- CHEVROLET SUBURBAN 1500/2500 (1998-1999)
- CHEVROLET TAHOE / GMC YUKON (1998-1999)
- CADILLAC ESCALADE (1999)
- CHEVROLET EXPRESS 1500/2500/3500 VAN (1998-1999)
- GMC SAVANA 1500/2500/3500 VAN (1998-1999)
- CHEVROLET ASTRO / GMC SAFARI (1998)
- CHEVROLET BLAZER S10 / GMC JIMMY S15 (1998)
- OLDSMOBILE BRAVADA (1998)
- GMC ENVOY (1998)
- CHEVROLET S10 / GMC SONOMA (1998)
- ISUZU HOMBRE (1998)
Note: This is a partial list. Please ensure your original module has ID 9355699 for guaranteed compatibility.
Frequently Asked Questions
Frequently Asked Questions
Do I need to do anything after I buy it?
Yes. After your purchase, you must send us your 17-digit VIN. We cannot program and ship the module without it. This ensures the PCM is a perfect match for your vehicle’s factory options.
Is this part difficult to install?
No, the physical installation is straightforward for most DIYers with basic tools. The most important part is performing the security relearn procedure correctly after the new PCM is installed, which does not require any special scan tools.
What is a security relearn procedure?
It’s a process that syncs your new PCM with your vehicle’s anti-theft system (VATS/Passlock). Without it, the vehicle will not start. The procedure involves a simple sequence of turning the key on and off, as detailed in our installation guide.
Will this fix my transmission shifting problems?
In many cases, yes. The PCM also controls transmission line pressure and shift points. If the PCM is failing, it can cause hard shifts, delayed shifting, or slipping. This programmed module restores those factory settings.
Why should I buy a used PCM?
This is a cost-effective and reliable solution. You get a genuine GM part that has been tested and professionally programmed with the latest software, providing the same function as a much more expensive new unit from a dealer.