Restore Peak Performance to Your GM Truck or Van
Is your trusty 1998-1999 GMC 1500 Pickup suddenly running rough, stalling, or throwing a stubborn Check Engine light? As a technician with over two decades of experience under the hood, I know how frustrating and confusing these electronic issues can be. The Powertrain Control Module (PCM) is the brain of your vehicle, managing everything from fuel mixture and ignition timing to transmission shifting. When it starts to fail, it can cause a cascade of problems that are often misdiagnosed.
This isn’t just a used part pulled from a yard; it’s a cost-effective, reliable solution. We take a thoroughly tested, OEM PCM and flash it with the latest official GM software updates specifically for your vehicle. By providing your Vehicle Identification Number (VIN) during checkout, you receive a module that is ready to install, saving you a costly trip to the dealership for programming. This is the most direct path to getting your truck running smoothly again.
A Technician’s Notebook: The Intermittent Gremlin
I once had a 1999 Chevy Suburban in my bay with an issue that drove the owner crazy. It would run perfectly for days, then suddenly start shifting hard and idling poorly, only for the problem to vanish by the time he got to the shop. There were no consistent codes, just a history of random communication errors. After checking all the wiring and grounds, we swapped in a known-good, correctly programmed PCM. The problem never returned. The original PCM had an internal intermittent fault on the circuit board, a classic failure mode for these units that heat and vibration take a toll on over the years. This highlights why replacing the entire 1998-1999 GMC 1500 PCM is often the only permanent fix.
Is Your Vehicle Showing These Symptoms?
A failing PCM can manifest in many ways. If you’re experiencing any of the following, this module is the likely solution:
- ✔ Unexplained Check Engine Light with codes like P0601 (Internal Control Module Memory Check Sum Error) or P0606 (ECM/PCM Processor Fault).
- ✔ Vehicle refuses to start or stalls intermittently.
- ✔ Harsh or erratic automatic transmission shifting.
- ✔ A noticeable drop in fuel economy.
- ✔ Engine performance issues like rough idling, hesitation, or misfiring.
- ✔ Communication errors with your scan tool.
A Straightforward Guide to Installation
Installing your pre-programmed 1998-1999 GMC 1500 PCM is a job most DIYers can handle in under an hour with basic hand tools. Following these steps ensures a smooth process.
- Safety First: Always disconnect the negative terminal from your vehicle’s battery and wait at least 15 minutes for the system to discharge.
- Locate the PCM: On most of these trucks and vans, the PCM is located in the engine compartment, typically on the driver’s side inner fender or near the battery.
- Disconnect the Connectors: Carefully unclip and remove the wiring harness connectors. These have locking tabs, so don’t force them. Inspect the pins for any corrosion or damage.
- Remove the Old Module: Unbolt the PCM from its mounting bracket and remove it from the vehicle.
- Install the New Module: Bolt your new, pre-programmed PCM into the mounting bracket.
- Reconnect Everything: Firmly plug the wiring harness connectors back into the new PCM until they click into place. Reconnect the negative battery terminal.
- Perform Security Relearn: After installation, you MUST perform the GM Passlock/VATS security relearn procedure. This typically involves turning the key to the ‘ON’ position for 10-15 minutes, then ‘OFF’ for 10 seconds, and repeating this cycle three times. Your vehicle will not start until this is completed.
Verified Vehicle Compatibility
This module is a direct replacement for service number 16266645 and other interchangeable part numbers like 09355699. It is guaranteed to fit the following vehicles (please match ID 9355699 where specified):
- Cadillac Escalade: 1999
- Chevrolet 1500/2500/3500 Pickup: 1998-1999 (Gasoline)
- Chevrolet Astro Van: 1998
- Chevrolet Blazer S10: 1998
- Chevrolet Express 1500/2500/3500 Van: 1998-1999 (Gasoline)
- Chevrolet S10 Pickup: 1998 (4.3L)
- Chevrolet Suburban 1500/2500: 1998-1999 (Gasoline)
- Chevrolet Tahoe: 1998-1999 (Gasoline)
- GMC 1500/2500/3500 Pickup: 1998-1999 (Gasoline)
- GMC Envoy: 1998
- GMC Jimmy S15: 1998
- GMC Safari Van: 1998
- GMC Savana 1500/2500/3500 Van: 1998-1999 (Gasoline)
- GMC Sonoma: 1998 (4.3L)
- GMC Yukon: 1998-1999
- Isuzu Hombre: 1998 (4.3L)
- Oldsmobile Bravada: 1998
Frequently Asked Questions About Your 1998-1999 GMC 1500 PCM
Frequently Asked Questions
Do I need to do anything after I install it?
Yes. After installing the PCM and reconnecting the battery, you must perform the vehicle’s security relearn procedure (often called Passlock or VATS). This syncs the new PCM with your vehicle’s anti-theft system. The procedure is simple and does not require special tools. Your truck will not start until this is done.
Is this a new part?
No, this is a high-quality, tested computer that has been sourced from a salvaged vehicle. We verify its function and then program it with the latest GM software for your specific VIN, offering a reliable and affordable alternative to a new dealer part.
How do I provide my VIN?
After you complete your purchase, you will need to send us your 17-digit VIN. We cannot program and ship your PCM without it. Please double-check it for accuracy to ensure perfect compatibility.
Will this fix my specific problem?
This PCM will resolve issues directly caused by a faulty module, such as internal processor errors (P0601, P0606), and many drivability problems. However, it’s important to ensure your vehicle’s issues are not caused by other failing parts like sensors or bad wiring. A proper diagnosis is always recommended.
What if I have modifications on my vehicle?
Our programming service installs the latest official GM calibration for your vehicle based on the VIN you provide. This programming is intended for stock or near-stock vehicles. It is not designed for vehicles with significant engine or powertrain modifications.