Restore Your Truck’s Brain: Pre-Programmed PCM for 1998-1999 GMC 3500
Is your reliable GMC 3500 suddenly giving you headaches? Stalling, running rough, or flashing a stubborn Check Engine Light can be incredibly frustrating, especially when you depend on your truck for work. Often, the root cause isn’t a mechanical failure but a problem with the Powertrain Control Module (PCM)—the central computer of your vehicle. This replacement 1998-1999 GMC 3500 PCM is the straightforward, reliable solution to get your truck back in top form without the excessive cost and hassle of a dealership visit.
We take the guesswork and complexity out of the repair. This is a quality, inspected used OEM module that we program specifically for your truck. Simply provide your Vehicle Identification Number (VIN) after purchase, and our technicians will flash the unit with the latest GM software updates. This ensures it communicates perfectly with your engine, transmission, and all other onboard systems right out of the box. It’s a direct-fit replacement for part number 16266645 and several other compatible service numbers, designed to restore original performance and reliability.
Case Study: The Ghost in the Machine
A few months back, a 1999 Chevy Suburban (which uses the same family of PCM) was towed into the shop. The owner had already replaced the fuel pump and ignition coil trying to solve an intermittent no-start and stalling issue. It would run fine for days, then die without warning. After hooking up my scan tool, I noticed a key symptom: the scanner would lose communication with the PCM right before it stalled. This is a classic sign of internal PCM failure. We installed one of our pre-programmed modules, performed the quick security relearn, and the truck fired up instantly. The customer called a week later, thrilled that his truck was finally dependable again. It wasn’t a ghost, just a faulty computer.
Is Your GMC Truck Showing These Signs?
A failing PCM can cause a wide range of confusing symptoms. If you’re experiencing any of the following, a faulty module is a likely culprit:
- ✔ Check Engine Light is on with communication error codes (like U0100) or internal processor fault codes (like P0601, P0606).
- ✔ The engine cranks but refuses to start.
- ✔ Unexplained stalling or rough idling, even after a tune-up.
- ✔ Noticeable decrease in fuel economy.
- ✔ Harsh or erratic automatic transmission shifting.
- ✔ Failure to pass an emissions test.
A Straightforward Guide to Installation
Installing your pre-programmed 1998-1999 GMC 3500 PCM is a job most DIYers can handle in under an hour. While the exact location can vary slightly, it’s typically found in the engine bay. After installation, you will need to perform a security relearn procedure, which does not require a scan tool.
- Safety First: Disconnect the negative terminal from your truck’s battery.
- Locate the PCM: On most GMT400 platform trucks, the PCM is located on the driver’s side of the engine compartment, near the fender or firewall.
- Disconnect Connectors: Carefully unclip and remove all wiring harness connectors from the old PCM. Inspect the connectors for any corrosion or bent pins.
- Remove the Old Module: Unbolt the 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-fasten the bolts.
- Reconnect Everything: Firmly plug all wiring harnesses back into their correct slots on the new PCM. Reconnect the negative battery terminal.
- Perform Security Relearn: A simple key-cycle procedure is required to sync the new PCM with your vehicle’s anti-theft system. Instructions will be included with your part.
Verified Vehicle Compatibility
This module, identified by hardware ID 9355699, is the correct replacement for a wide range of General Motors trucks and vans. We program it specifically for your vehicle’s VIN. It is a guaranteed fit for the following models requiring this specific ID:
- ✔ 1998-1999 Chevrolet & GMC 1500, 2500, & 3500 Pickups (Gasoline)
- ✔ 1998-1999 Chevrolet Tahoe & GMC Yukon (Gasoline)
- ✔ 1998-1999 Chevrolet & GMC Suburban (Gasoline)
- ✔ 1998-1999 Chevrolet Express & GMC Savana 1500, 2500, 3500 Vans (Gasoline)
- ✔ 1999 Cadillac Escalade
- ✔ 1998 Chevrolet Astro & GMC Safari
- ✔ 1998 Oldsmobile Bravada, GMC Envoy, S10/S15/Sonoma, Blazer/Jimmy, Isuzu Hombre (4.3L V6 models)
Note: This part directly replaces service numbers 09355699, 16266645, 16250279, 16258815, and 09366810. Please verify your original part number or contact us for fitment confirmation.
Frequently Asked Questions
Frequently Asked Questions
Do I need to do anything after I install it?
Yes. While we program the module to your VIN, you must perform a security relearn procedure (also known as a CASE or Crankshaft Variation Relearn) so it syncs with your truck’s anti-theft system. This is a simple procedure that involves turning the key on and off and does not require special tools. We include instructions to make it easy.
Is this a new part?
No, this is a high-quality, inspected, and tested used OEM part sourced from a salvaged vehicle. This provides OEM reliability at a fraction of the cost of a new module.
What information do you need from me?
After you complete your purchase, you must provide us with your 17-digit Vehicle Identification Number (VIN). We cannot ship your part until we receive your VIN, as it is required for the programming service.
Will this fix my truck’s problem?
This part is a direct solution for a failed PCM. If your vehicle has been properly diagnosed with a faulty PCM, this part will resolve the related issues. It will not fix other mechanical or electrical problems (e.g., a bad fuel pump or wiring short).
What if my part number is slightly different?
This module is compatible with several part numbers, including 09355699, 16250279, and others listed. The key is the hardware ID and the correct programming. If you’re unsure, send us a message with your VIN and original part number, and we’ll verify compatibility for you.