Restore Your Truck’s Brain and Get Back on the Road
Is your trusty 1998-1999 GMC 2500 Pickup suddenly running rough, refusing to start, or throwing a stubborn Check Engine Light? You’re not just dealing with a simple sensor failure; you could be facing a faulty Powertrain Control Module (PCM), the central computer of your vehicle. A failing PCM can cause a cascade of frustrating issues, from poor fuel mileage to unpredictable stalling. This isn’t just an inconvenience; it’s a reliability problem that can leave you stranded. This replacement module is your direct-fit, hassle-free solution to restore your truck’s performance and dependability.
From the Diagnostic Bay: The Case of the Intermittent Sierra
I remember a ’99 GMC Sierra 2500 that came into my shop a while back. The owner was at his wit’s end. The truck would run fine for days, then suddenly stall at a stoplight or hesitate badly under acceleration. He’d already replaced the fuel pump and a couple of sensors with no luck. When I hooked up my professional scan tool, I found the tell-tale code: P0601 – Internal Control Module Memory Check Sum Error. This code doesn’t point to a sensor or wire; it’s a definitive sign that the PCM’s internal processor is failing. We swapped in a VIN-programmed module just like this one, and the truck ran perfectly. It’s a classic scenario for these workhorse trucks, and this is the correct fix.
Is Your GM Truck Showing These Signs?
A failing PCM can manifest in many ways. If you’re experiencing any of the following, it’s a strong indicator that your engine computer needs replacement. This 1998-1999 GMC 2500 PCM is designed to solve these exact problems.
- ✔ Stubborn Check Engine Light that won’t clear
- ✔ Engine cranks but refuses to start (no-start condition)
- ✔ Unexplained drop in fuel economy
- ✔ Harsh or erratic automatic transmission shifting
- ✔ Engine stalling, stumbling, or hesitating
- ✔ Failed emissions test
- ✔ Diagnostic Trouble Codes (DTCs) such as P0601, P0605, or other U-codes indicating communication loss
A Straightforward Guide to Installation
One of the biggest advantages of this module is that it arrives programmed to your vehicle’s VIN. This eliminates the need for an expensive trip to the dealership. You can install this at home with basic hand tools.
- Safety First: Always disconnect the negative terminal from your vehicle’s battery before starting any electrical work.
- Locate the PCM: On most 1998-1999 GMC 2500 trucks, the PCM is located in the engine compartment on the driver’s side, often near the fender or firewall. It’s a silver box with multiple large wiring harness connectors.
- Disconnect and Remove: Carefully unplug the wiring harness connectors. They have locking tabs that need to be released. Once disconnected, unbolt the old PCM from its mounting bracket.
- Install the New Module: Bolt the new PCM into the bracket and securely reconnect all wiring harnesses. Ensure they click into place.
- Reconnect Power: Reattach the negative battery terminal.
- Perform Idle Relearn (Recommended): Start the engine and let it idle in Park for 3-5 minutes. Then, turn it off for one minute. Repeat this cycle once more to allow the computer to learn the engine’s idle characteristics. Your truck is now ready to drive.
Verified Vehicle Compatibility
This module is a direct replacement for part numbers 09355699, 16250279, and 09366810. It is guaranteed to fit the following vehicles. Please match your vehicle and original part ID to ensure proper fitment.
GMC/CHEVROLET 1500 PICKUP 98-99 (Gasoline, LH engine compartment), ID 16250279
GMC/CHEVROLET 2500 PICKUP 98-99 (Gasoline, LH front engine compartment), ID 16250279
GMC/CHEVROLET 3500 PICKUP 98-99 (Gasoline, LH front engine compartment), ID 16250279
SUBURBAN 1500/2500 98-99 (Gasoline, LH front engine compartment), ID 16250279
TAHOE/YUKON 98-99 (LH engine compartment), ID 16250279
ASTRO/SAFARI 98-99 (LH front by battery), ID 16250279
EXPRESS/SAVANA 1500/2500/3500 VAN 98 (Gasoline), ID 16250279
BLAZER S10/JIMMY S15 98 (RH front engine compartment), w/o build date opt ZN4; ID 16250279 or 16258815
S10/S15/SONOMA 98 (4.3L), w/o build date opt ZN4; ID 16250279 or 16258815
BRAVADA 98 (4.3L), w/o build date opt ZN4; ID 16250279 or 16258815
ENVOY 98 (RH front engine compartment), w/o build date opt ZN4; ID 16250279 or 16258815
ISUZU HOMBRE 98 (4.3L), w/o extended build date opt ZN4; ID 16258815
Frequently Asked Questions
Do I need to do anything after I purchase?
Yes. After your purchase, please send us a message with your vehicle’s 17-digit VIN. We need this to program the module with the latest GM software specific to your truck before we ship it.
Is this a plug-and-play part?
Absolutely. Because we program it with your VIN, it is ready for installation right out of the box. No dealer visit or special tools are required for programming. Some vehicles may require a simple idle relearn procedure as outlined in our installation guide.
Will this fix my transmission shifting problems?
In many cases, yes. The PCM controls both engine and transmission functions. If the computer is failing, it can send incorrect signals to the transmission, causing harsh or erratic shifting. Replacing a faulty PCM often resolves these issues.
What if my original part number is 16250279?
This module is a fully compatible replacement. Part number 09355699 is an updated or interchangeable part for 16250279 and 09366810, and it will function identically in your vehicle once programmed.
Do I need to send my old PCM back?
No, there is no core charge or requirement to return your old module.