1998-1999 GMC 1500 PCM 16250279 | Programmed to Your VIN

Is Your Trusty GM Truck or Van Acting Up?

If you’re dealing with frustrating issues on your 1998 or 1999 GMC 1500, Chevrolet truck, or another GM vehicle from that era, the problem might be deeper than a simple sensor. After 20+ years on the road, the original Powertrain Control Module (PCM) can start to fail, leading to problems that are often difficult to diagnose. As the ‘brain’ of your vehicle, a faulty PCM can cause a cascade of confusing symptoms.

Common Signs of a Failing GM PCM

In my two decades of hands-on diagnostics, I’ve seen countless late-90s GM trucks and vans come into the shop with these exact issues. A failing PCM is often the root cause if you’re experiencing:

• ✔ Unexplained Check Engine Light that won’t go away.
• ✔ Rough or erratic idling, sometimes stalling at stops.
• ✔ Harsh or incorrect transmission shifting.
• ✔ A complete no-start condition where the engine cranks but won’t fire up.
• ✔ Poor fuel economy and a noticeable loss of power.
• ✔ Communication errors with diagnostic scan tools.

The Direct Solution: A VIN-Programmed 1998-1999 GMC 1500 PCM

Don’t let a bad computer sideline your reliable vehicle. This is a dependable, used OEM Powertrain Control Module that has been sourced from a salvaged vehicle and is ready for a new life in your truck. The key to our service is that we flash the module with the latest GM-approved software specifically for your vehicle’s VIN. This isn’t a generic, one-size-fits-all part; it’s prepared to communicate perfectly with your truck’s specific engine, transmission, and options right out of the box.

Expert Pro Tip from 20+ Years in the Bay: Before you swap out your PCM, do a simple but critical check. On these GMT400 and similar platform vehicles, a corroded or loose ground wire can cause symptoms identical to a failing PCM. Look for the main ground straps from the engine block to the frame and the firewall. I’ve seen customers save hundreds of dollars just by cleaning these connections with a wire brush. If your grounds are solid and the problems persist, the PCM is your next logical step.

Plug-and-Play Installation: No Dealer Visit Required

We handle the programming so you don’t have to. Once you receive your module, installation is straightforward for a DIYer with basic tools. Here’s a general guide:

1. Safety First: Always disconnect the negative terminal from your vehicle’s battery.
2. Locate the PCM: On most 1998-1999 GM trucks, the PCM is located in the engine compartment on the driver’s side, often near the fender or firewall. In vans, it’s typically in the LH rear engine compartment.
3. Disconnect the Harnesses: Carefully unclip and remove the electrical connectors. Inspect them for any corrosion or bent pins.
4. Remove the Old Module: Unbolt the PCM from its mounting bracket.
5. Install the New Module: Bolt your replacement PCM into place and securely reconnect the electrical harnesses. You should hear a ‘click’ as they lock in.
6. Reconnect the Battery: Attach the negative battery terminal. The vehicle may need to complete a security relearn procedure, which typically involves turning the key to ‘ON’ for 10-15 minutes.

Guaranteed Compatibility

This module is a direct replacement for a wide range of GM vehicles and is guaranteed to work if your original part number is one of the following. It is specifically compatible with vehicles that use service ID 9355699.

• Part Numbers: 09355699, 16266645, 16250279, 16258815, 09366810, 9366810
• Primary Fitment: 1998-1999 Chevrolet & GMC C/K 1500, 2500, 3500 Pickups, Suburban, Tahoe, Yukon, Escalade, Express, Savana, and more. Please verify your part number or consult the detailed fitment list to ensure this is the correct part for your vehicle.

IMPORTANT: After your purchase, you must provide us with your vehicle’s 17-digit VIN. We cannot ship your order until we have this information to program the module correctly.