Restore Your Truck’s Brain and Get Back on the Road
As a mechanic with over two decades of experience under the hood, I know the frustration of a truck that won’t run right. When your 1998-1999 Chevrolet 3500 starts acting up with bizarre electrical gremlins, stalling for no reason, or refusing to start, the problem often points to the very brain of the operation: the Powertrain Control Module (PCM). This isn’t just another part; it’s the central command for your engine and transmission. A failing one can make even the toughest truck feel unreliable.
This is a dependable, tested, and ready-to-install PCM, service number 16258815. We take the guesswork and hassle out of the replacement process. Before this module ships, we flash it with the latest official GM software updates, specifically programmed to your truck’s unique Vehicle Identification Number (VIN). This ensures seamless communication between all your vehicle’s systems, restoring the performance and reliability you depend on. You’re not just getting a replacement part; you’re getting a plug-and-play solution that corrects common issues and gets your workhorse back in service.
From the Diagnostic Bay: The Case of the Intermittent Stall
I remember a customer bringing in his ’99 GMC Sierra 2500, a cousin to this Chevy 3500, with a problem that had two other shops stumped. It would run perfectly for days, then suddenly stall at a stoplight and refuse to restart for an hour. There were no consistent trouble codes, just a random P0601 (Internal Control Module Memory Check Sum Error) that would appear and disappear. After checking all the usual suspects—fuel pressure, ignition system, grounds—we focused on the PCM. On these GMT400 trucks, years of heat cycles and engine vibration can cause microscopic cracks in the PCM’s circuit board. We swapped in a VIN-programmed module just like this one, and the problem vanished instantly. The customer called a month later, thrilled that his truck was finally reliable again. That’s the difference a quality, correctly programmed PCM can make.
Is Your Truck Showing These Symptoms?
A failing PCM can manifest in numerous ways. If you’re experiencing any of the following, this module is the likely solution:
- ✔ Check Engine Light is on with codes like P0601, P0604, or P0606.
- ✔ The engine cranks but refuses to start.
- ✔ Unexplained stalling or rough idling.
- ✔ A noticeable drop in fuel economy.
- ✔ Harsh or erratic automatic transmission shifting.
- ✔ Communication errors with your scan tool.
A Straightforward Guide to Installation
Replacing the 1998-1999 Chevrolet 3500 PCM is a job most DIYers can handle in their own driveway. Follow these steps for a smooth installation.
- Safety First: Always disconnect the negative terminal from your truck’s battery and secure it away from the post to prevent any accidental power surges.
- Locate the PCM: On most of these trucks, 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 electrical connectors.
- Disconnect the Connectors: Carefully unlatch and remove all wiring harness connectors from the old PCM. These connectors have locking tabs that need to be released. Avoid pulling on the wires themselves.
- Remove the Old Module: Unbolt the PCM from its mounting bracket. Keep the hardware, as you may need it for the new module.
- Install the New PCM: Mount your new, pre-programmed PCM onto the bracket and securely fasten it. Reconnect the wiring harnesses, ensuring each plug is fully seated and the locking tabs click into place.
- Reconnect the Battery: Reattach the negative battery terminal and tighten it.
- Perform Security Relearn: Your vehicle’s anti-theft system (PassLock/VATS) needs to sync with the new PCM. The standard procedure is to turn the key to the ‘ON’ position (without starting) for 10-15 minutes, then turn it ‘OFF’ for 10 seconds. Repeat this cycle 3 times. On the fourth try, the vehicle should start.
Verified Vehicle Compatibility
This module is a direct replacement for service number 16258815 and other interchangeable part numbers (such as 09355699 and 16266645). It is guaranteed to fit a wide range of GM trucks and vans, including:
- ✔ 1998-1999 Chevrolet & GMC C/K 1500, 2500, 3500 Pickups (Gasoline)
- ✔ 1998-1999 Chevrolet Suburban & GMC Suburban (Gasoline)
- ✔ 1998-1999 Chevrolet Tahoe & GMC Yukon (Gasoline)
- ✔ 1999 Cadillac Escalade
- ✔ 1998-1999 Chevrolet Express & GMC Savana 1500, 2500, 3500 Vans (Gasoline)
- ✔ 1998 Chevrolet Astro & GMC Safari
- ✔ 1998 Oldsmobile Bravada, GMC Envoy, Chevrolet Blazer S10, GMC Jimmy S15, Chevrolet S10, GMC Sonoma, Isuzu Hombre (4.3L V6)
Please provide your VIN upon purchase to ensure we send you a perfectly matched and programmed 1998-1999 Chevrolet 3500 PCM for your specific vehicle.