Restore Your Truck’s Core Performance and Reliability
As a technician with over two decades of experience, I’ve seen firsthand how a failing Powertrain Control Module (PCM) can bring even the toughest trucks to a dead stop. If your 1998-1999 GMC 3500, or another compatible GM vehicle, is suffering from baffling issues like intermittent stalling, no-start conditions, poor fuel economy, or a persistent check engine light, the PCM is often the culprit. It’s the brain of your vehicle, and when it malfunctions, nothing works right. This isn’t just an inconvenience; it’s a reliability issue that can leave you stranded.
This is a dependable, tested, and pre-programmed replacement PCM, service number 09355699. We take the guesswork and high cost out of the repair. Instead of paying for an expensive new unit and then paying the dealer again for programming, we handle it all for you. Simply provide your vehicle’s 17-digit VIN during checkout, and our experts will flash this module with the latest GM software specific to your truck. This ensures it communicates perfectly with your engine, transmission, and security system right out of the box.
A Technician’s Notebook: The Phantom No-Start
I remember a 1999 Chevy Suburban that came into my bay with a frustrating intermittent no-start. The owner had already replaced the battery, starter, and fuel pump. It would run fine for days, then refuse to start, only to fire right up an hour later. After hours of tracing wires and checking grounds, I noticed the failure only happened on hot days after the truck had been sitting. On a hunch, I used a heat gun on the PCM. Sure enough, once it got warm, the engine wouldn’t start. A quick swap with a known-good module confirmed it: the original PCM had an internal failure that was sensitive to temperature. This is a classic symptom I’ve seen dozens of times on these GM platforms.
Is Your Truck Exhibiting These Failure Signs?
A failing PCM can cause a wide range of symptoms. If you’re experiencing any of the following, this module is a likely solution:
- ✔ Check Engine Light is on with communication error codes (e.g., P0601, P0605, U-series codes).
- ✔ Engine cranks but will not start.
- ✔ Intermittent stalling or rough idling for no apparent reason.
- ✔ Noticeable decrease in fuel efficiency.
- ✔ Harsh or erratic automatic transmission shifting.
- ✔ Apparent loss of spark or fuel injector pulse.
- ✔ The vehicle’s security or anti-theft light stays on.
A Straightforward Guide to Installation
Replacing the PCM on these GM trucks is a job most DIYers can handle in under 30 minutes with basic hand tools. Because we pre-program the unit to your VIN, you skip the most difficult step. After installation, you will only need to perform a simple security relearn procedure.
- Safety First: Disconnect the negative terminal from your vehicle’s battery to prevent any electrical shorts.
- Locate the PCM: On most trucks and SUVs, it’s located in the engine compartment on the driver’s side, near the fender or firewall. On Express/Savana vans, it’s often in the LH rear engine compartment.
- Disconnect the Connectors: Carefully unclip and remove the electrical harness connectors from the old PCM. Inspect them for any corrosion or damage.
- Remove the Old Module: Unbolt the old PCM from its mounting bracket and remove it from the vehicle.
- Install the New Module: Mount your new, pre-programmed PCM onto the bracket and securely re-attach the electrical connectors. You should hear a ‘click’ as they lock in place.
- Reconnect the Battery: Re-attach the negative battery terminal.
- Perform Security Relearn: You will need to complete the GM Passlock/VATS security relearn procedure. This typically involves turning the key to the ‘ON’ position for 10-15 minutes, then off, and repeating the cycle 2-3 times until the security light goes out. This syncs the new PCM to your vehicle’s anti-theft system.
Verified Compatibility for Your GM Vehicle
This module, identified by service number 09355699, is a direct replacement for several part numbers, including 16266645, 16250279, 16258815, and 09366810. It is guaranteed to fit the following gasoline-engine vehicles, provided the ID on your original module matches:
- ✔ Chevrolet/GMC 1500/2500/3500 Pickups (1998-1999)
- ✔ Chevrolet/GMC Suburban 1500/2500 (1998-1999)
- ✔ Chevrolet Tahoe / GMC Yukon (1998-1999)
- ✔ Cadillac Escalade (1999)
- ✔ Chevrolet Express / GMC Savana 1500/2500/3500 Vans (1998-1999)
- ✔ Chevrolet Astro / GMC Safari (1998)
- ✔ Chevrolet S10 / GMC Sonoma / Isuzu Hombre (1998, 4.3L V6)
- ✔ Chevrolet Blazer / GMC Jimmy / Oldsmobile Bravada (1998)
Frequently Asked Questions
What exactly does this PCM do?
The Powertrain Control Module (PCM) is the central computer for your vehicle’s engine and transmission. It controls critical functions like fuel injection, ignition timing, emissions systems, and automatic transmission shift points to ensure optimal performance and efficiency.
Do I really need to provide my VIN?
Yes, absolutely. Providing your 17-digit Vehicle Identification Number (VIN) is critical. We use it to load the correct GM-certified software for your vehicle’s specific engine, transmission, and options. This step is what makes the installation simple and ensures the module works correctly upon arrival.
Is a security relearn procedure difficult?
Not at all. The GM security relearn is designed to be done without any special tools. It’s a simple key-cycle process that takes about 30 minutes. Instructions are widely available online for your specific model, or you can consult your vehicle’s service manual.
Is this a new part?
No, this is a high-quality, used OEM part sourced from a salvaged vehicle. Each unit is thoroughly inspected, tested, and professionally programmed to function like new. This provides you with the reliability of a genuine GM part at a fraction of the cost of a new one from a dealer.
What if my part number is slightly different?
This module replaces a range of compatible part numbers, including 16266645, 9355699, 16250279, 16258815, and 09366810. As long as your vehicle is on the compatibility list and your original module has one of these service numbers, this part will work perfectly once programmed to your VIN.