Get Your Workhorse Back on the Road
If your trusty 1998-1999 GMC 1500 is suddenly stalling, shifting erratically, or refusing to start, the problem often points directly to a failing Powertrain Control Module (PCM). As a technician with over two decades of experience, I’ve seen firsthand how a faulty PCM can cause a cascade of frustrating, hard-to-diagnose issues. It’s the brain of your truck’s operation, and when it goes, everything from fuel delivery to spark timing is compromised. This isn’t just an inconvenience; it’s a reliability issue that can leave you stranded.
This is a reliable, tested, and ready-to-install solution. We’ve taken a quality, used OEM PCM and prepared it specifically for your vehicle. The biggest headache with PCM replacement is the programming—a step that usually requires an expensive trip to the dealership. We handle that for you. Simply provide your vehicle’s VIN at checkout, and we will flash this module with the latest, most stable GM software updates specific to your truck. This ensures optimal performance and resolves many of the software glitches that may have developed in your original unit over the years. This is the most direct path to solving your truck’s electronic woes and restoring its dependability.
From the Diagnostic Bay: The Intermittent No-Start Nightmare
I remember a ’99 Chevy 1500 that came into my shop on a tow truck. The owner was at his wit’s end. It would start and run perfectly for weeks, then suddenly refuse to start for a day. He’d already replaced the battery, starter, and fuel pump. When I connected my scan tool, I got a ‘No Communication’ error with the PCM. After checking the power and ground circuits to the module—which were solid—I knew the culprit. The internal circuits of the original PCM were failing intermittently due to heat and age. We installed a VIN-programmed PCM just like this one, and the truck never had the issue again. It’s a classic failure on these GMT400 and early GMT800 platform vehicles.
Is Your GM Truck or Van Showing These Symptoms?
- ✔ Check Engine Light is on with codes like P0601 (Internal Control Module Memory Check Sum Error) or other communication faults.
- ✔ The engine cranks but refuses to start (no-start condition).
- ✔ Unexplained stalling, especially after the engine has warmed up.
- ✔ Harsh or erratic automatic transmission shifting.
- ✔ A noticeable drop in fuel economy.
- ✔ The anti-theft or security light stays on, preventing the engine from starting.
- ✔ Inconsistent or non-functional gauges on the instrument cluster.
A Straightforward Guide to Installation
Replacing the 1998-1999 GMC 1500 PCM is a job most DIYers can handle with basic tools. The key is our pre-programming service, which eliminates the most complex step.
- Safety First: Always disconnect the negative terminal from your vehicle’s battery and wait at least 10 minutes for the system capacitors to discharge.
- 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. It’s a silver metal box with several large wiring harness connectors.
- Disconnect the Harnesses: Carefully release the locking tabs on each electrical connector and pull them straight out from the PCM. Avoid pulling on the wires themselves.
- Remove the Old Module: Unbolt the PCM from its mounting bracket. There are typically two or three bolts holding it in place.
- Install the New Module: Mount your new, pre-programmed PCM onto the bracket and secure it with the bolts. Reconnect the wiring harnesses, ensuring they click securely into place.
- Reconnect the Battery: Reattach the negative battery terminal.
- Perform Security Relearn: You will likely need to perform a simple security relearn procedure. This 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 module, identified by part number 09355699, is a direct fit for a wide range of GM vehicles. Please match your original part number or confirm your vehicle is on this list. This unit is compatible with service numbers 16266645, 9355699, 16250279, 16258815, 09366810, and 9366810.
ASTRO 98, BLAZER S10/JIMMY S15 98, BRAVADA 98, CADILLAC ESCALADE 99, CHEVROLET/GMC 1500/2500/3500 PICKUPS 98-99, ENVOY 98, EXPRESS/SAVANA 1500/2500/3500 VANS 98-99, ISUZU HOMBRE 98, S10/S15/SONOMA 98, SAFARI (GMC) 98, SUBURBAN 1500/2500 98-99, TAHOE/YUKON 98-99.
Note: Specific engine and option compatibility is detailed in the original product data. Please verify your specific application.
Frequently Asked Questions
Do I need to do any programming after I receive this PCM?
No. This PCM arrives pre-programmed to your vehicle’s specific VIN. The only additional step you may need is a simple key-cycle security relearn procedure, which does not require any special tools.
How do I provide my VIN?
After you complete your purchase, you will need to send us your 17-digit Vehicle Identification Number (VIN). We cannot ship your part until we receive this information for programming.
Is this a new part?
No, this is a high-quality, tested used OEM part that has been sourced from a salvaged vehicle. It has been inspected and flashed with the latest GM software for your VIN.
What is a security relearn procedure?
It’s a simple process that syncs the new PCM with your vehicle’s anti-theft system. It typically involves turning the ignition on for 10 minutes, off for 10 seconds, and repeating this cycle three times. Your vehicle’s manual will have the exact steps.
Will this fix my truck’s check engine light?
If the check engine light is caused by a faulty PCM (e.g., code P0601), then yes, this part is the correct fix. However, you should always diagnose the codes properly to ensure the PCM is the root cause and not another sensor or component.