Restore Your Truck’s Brain and Get Back on the Road
If you’re dealing with frustrating, hard-to-diagnose issues on your 1998-1999 GM truck or van, the problem often points to a failing Powertrain Control Module (PCM). As a technician with over two decades of experience under the hood, I’ve seen it all: no-start conditions that appear out of nowhere, erratic transmission shifting, a persistent Check Engine Light, and poor fuel economy that just won’t resolve. These aren’t just annoyances; they’re signs that the central computer of your vehicle is failing. This isn’t just a part; it’s the solution to getting your reliable workhorse running right again.
This is a dependable, tested, and used OEM PCM, part number 9355699, sourced from a salvaged vehicle. The real value here is our in-house programming service. Before we ship it, we flash the module with the latest official GM software updates, specifically matched to your vehicle using the VIN you provide. This means you receive a 1998-1999 Suburban 1500 PCM that is ready for installation, saving you a costly trip to the dealership and the headache of coordinating programming. It’s the smart, efficient fix for both seasoned mechanics and DIY enthusiasts.
A Technician’s Notebook: The Ghost in the Machine
I remember a ’99 Tahoe that came into the bay with a laundry list of intermittent electrical gremlins. The owner was at his wit’s end. Sometimes it wouldn’t start, other times the transmission would slam into gear, and the check engine light would flicker on and off with a P0601 (Internal Control Module Memory Check Sum Error) code. We checked wiring, grounds, and sensors for days. Everything seemed fine. On a hunch, we swapped in a known-good, programmed PCM. Every single issue vanished instantly. The original PCM’s internal processor was failing under thermal stress—a common fate for these units after 20+ years of heat cycles. This is why a reliable, correctly programmed PCM is often the definitive fix for problems that seem impossible to trace.
Is Your GM Truck Showing These Signs of PCM Failure?
A failing PCM can cause a wide range of symptoms. If your vehicle is experiencing any of the following, this module is likely the solution you need:
- ✔ Persistent Check Engine Light (CEL)
- ✔ Stored diagnostic trouble codes (DTCs) such as P0601, P0602, P0605, or other communication errors.
- ✔ Vehicle will not start or has a hard-starting condition.
- ✔ Harsh, erratic, or delayed transmission shifting.
- ✔ A noticeable drop in fuel economy.
- ✔ Engine stalling, sputtering, or misfiring.
- ✔ Failure to pass an emissions inspection.
A Straightforward Guide to Installation
Installing your replacement 1998-1999 Suburban 1500 PCM is a manageable job for a DIYer with basic tools. Follow these steps carefully for a smooth installation.
- Safety First: Always disconnect the negative terminal from your vehicle’s battery and wait at least 10 minutes to allow 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 inner fender or near the battery.
- Disconnect the Connectors: Carefully unclip and remove the electrical wiring harnesses from the old PCM. These connectors have locking tabs; be gentle to avoid breaking them.
- Remove the Old Module: Unbolt the old PCM from its mounting bracket. Keep the hardware as you will need it for the new module.
- Install the New Module: Mount your new, pre-programmed PCM onto the bracket and secure it with the original hardware.
- Reconnect and Secure: Firmly plug the wiring harnesses back into the new PCM until they click into place. Reconnect the negative battery terminal.
- Security Relearn Procedure: After installation, you will need to perform a security relearn (often called a Passlock relearn). This simple procedure typically involves turning the key to the ‘ON’ position for 10-15 minutes, then off, and repeating two more times. This allows your vehicle’s anti-theft system to recognize the new PCM.
Verified Vehicle Compatibility
This PCM, identified by part number 9355699, is a direct fit for a wide range of GM vehicles. It is compatible with other part numbers including 16266645, 16250279, 16258815, and 09366810. While programmed specifically for your VIN, it fits models such as:
- ✔ 1998-1999 Chevrolet & GMC Suburban (1500 & 2500, gasoline)
- ✔ 1998-1999 Chevrolet Tahoe & GMC Yukon (gasoline)
- ✔ 1998-1999 Cadillac Escalade
- ✔ 1998-1999 Chevrolet & GMC C/K Pickups (1500, 2500, 3500, gasoline)
- ✔ 1998-1999 Chevrolet Express & GMC Savana Vans (1500, 2500, 3500, gasoline)
- ✔ 1998 Chevrolet Astro & GMC Safari
- ✔ 1998 Oldsmobile Bravada, GMC Envoy, Chevrolet S10 Blazer, GMC S15 Jimmy
- ✔ 1998 Isuzu Hombre (4.3L)
Important: Always match your original part number or use our fitment guide to confirm compatibility. When you provide your VIN, we ensure the programming is a perfect match for your vehicle’s specific options.
Frequently Asked Questions
What information do I need to provide for programming?
After your purchase, you must provide us with your vehicle’s 17-digit Vehicle Identification Number (VIN). This allows us to load the correct, updated GM software for your specific engine, transmission, and options.
Is this a new part?
No, this is a high-quality, tested used OEM part that has been sourced from a salvaged vehicle. This provides OEM reliability at a fraction of the cost of a new module from a dealer.
Will I need to do anything else after installation?
Yes. After installing the PCM and reconnecting the battery, you must perform the vehicle’s security relearn procedure. This allows the anti-theft system to sync with the new computer. For some vehicles, a Crankshaft Variation Relearn (CASE relearn) may be needed with a scan tool to clear a P1336 code, though the vehicle will run and drive without it.
How do I find my VIN?
Your VIN can be found on your vehicle’s registration, insurance card, or on a metal plate on the driver’s side of the dashboard, visible through the windshield.
What if my original part number is slightly different?
This module (9355699) replaces several other part numbers like 16266645, 16250279, and more. As long as your vehicle is on the compatibility list, our VIN-based programming ensures it will function correctly.