Restore Peak Performance to Your GM Truck or Van
Is your trusty 1998-1999 GMC 1500 Pickup running rough, stalling unexpectedly, or showing a persistent Check Engine Light? As a technician with over two decades of experience under the hood, I’ve seen these symptoms countless times. Often, the root cause isn’t a faulty sensor or a bad fuel pump—it’s the vehicle’s brain, the Powertrain Control Module (PCM). This vital component manages everything from fuel injection and spark timing to transmission shifting. When it fails, it can create a cascade of frustrating and hard-to-diagnose problems.
This is a reliable, tested Powertrain Control Module (service number 16266645) that offers a direct-fit, cost-effective solution. We take the guesswork and hassle out of the repair. Before this PCM ships, our experts will program it specifically to your vehicle using your VIN. This ensures it has the latest GM software updates and communicates perfectly with your truck’s systems right out of the box. You get a part that’s ready for installation, saving you a costly trip to the dealership for programming.
A Technician’s Notebook: The Misleading No-Start
I once had a 1999 Chevy Tahoe towed into my bay that had stumped two other shops. The owner had already replaced the fuel pump, filter, and crank sensor, but it still wouldn’t start consistently. The scanner showed no communication with the PCM. After confirming the module was getting power and ground, it was clear the PCM itself had failed internally—a common issue on these GMT400 platforms. A replacement, programmed PCM like this one had the truck running perfectly in under 30 minutes. It’s a reminder that sometimes the most complex-seeming problems have a straightforward solution if you start with the central controller.
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 for your 1998-1999 GMC 1500 PCM issues:
- ✔ Check Engine Light is on with codes like P0601, P0605, or other internal controller errors.
- ✔ The engine cranks but refuses to start.
- ✔ Harsh, erratic, or delayed automatic transmission shifts.
- ✔ A noticeable drop in fuel economy.
- ✔ Intermittent stalling or rough idling.
- ✔ Failure to pass an emissions or smog test.
- ✔ No communication with your scan tool.
A Straightforward Guide to Installation
Installing your newly programmed 1998-1999 GMC 1500 PCM is a job most DIYers can handle with basic tools. Follow these steps for a smooth installation:
- Safety First: Always disconnect the negative terminal from your vehicle’s battery and wait 10-15 minutes for the system to fully discharge.
- Locate the PCM: On most of these GM trucks and vans, the PCM is located in the engine compartment, typically on the driver’s side fender well or near the battery.
- Disconnect the Wiring: Carefully unplug the electrical connectors from the old PCM. These connectors have locking tabs that may need to be gently pried up or squeezed to release.
- Remove the Old Module: Unbolt the old PCM from its mounting bracket. Keep the hardware, as you may need to reuse it.
- Install the New PCM: Mount your new, pre-programmed PCM onto the bracket and secure it. Reconnect the wiring harnesses, ensuring they click firmly into place.
- Reconnect the Battery: Reattach the negative battery terminal.
- Security Relearn (If Necessary): In some cases, a security relearn procedure may be required. This typically involves turning the key to the ‘ON’ position for 10-15 minutes, then ‘OFF’, and repeating two more times before starting the engine. Your vehicle’s service manual will have the exact procedure.
Verified Vehicle Compatibility
This module is a direct replacement for service number 16266645 and other part numbers listed below. It fits a wide range of GM vehicles from 1998-1999 that require the hardware ID 09355699. Please verify your part number or contact us with your VIN to confirm compatibility.
Interchangeable Part Numbers: 09355699, 16266645, 9355699, 16250279, 16258815, 09366810, 9366810
Partial Fitment List:
- Chevrolet & GMC C/K 1500/2500/3500 Pickups (1998-1999)
- Chevrolet Tahoe & GMC Yukon (1998-1999)
- Chevrolet & GMC Suburban (1998-1999)
- Chevrolet Express & GMC Savana Vans (1998-1999)
- Cadillac Escalade (1999)
- Chevrolet Astro & GMC Safari Vans (1998)
- Oldsmobile Bravada, Chevrolet S10 Blazer, GMC S15 Jimmy/Sonoma (1998)
- And more models requiring ID 09355699.
Frequently Asked Questions
Frequently Asked Questions
Do I need to do any programming myself?
No. We program the module to your vehicle’s specific VIN before we ship it. It arrives ready for installation, with no dealership visit required.
Is this a new part?
This is a high-quality, tested used part sourced from a salvaged vehicle. This allows us to provide a reliable, cost-effective solution for your repair needs.
What information do you need from me?
After you complete your purchase, you will need to provide us with your vehicle’s 17-digit VIN (Vehicle Identification Number). This is crucial for correct programming.
Where is the PCM located on my 1999 GMC Sierra?
On most 1998-1999 GMC and Chevy trucks, the PCM is located in the engine bay, mounted to the inner fender on the driver’s side.
Will this fix my transmission shifting problems?
In many cases, yes. The PCM controls transmission line pressure and shift points. If the module is faulty, it can cause harsh or erratic shifting, and a correctly programmed replacement will resolve these issues.
Is a security relearn procedure difficult?
Not at all. The GM Passlock/VATS security relearn is a simple key-cycle procedure that takes about 30 minutes and requires no special tools. We can provide instructions if needed.