Restore Peak Performance to Your GM Truck or Van
Is your 1998-1999 GMC Savana, Chevrolet Express, or another GM truck from this era suffering from frustrating issues like stalling, rough idling, or a persistent check engine light? The Powertrain Control Module (PCM), the central computer for your engine and transmission, is often the culprit. This isn’t just a replacement part; it’s a complete, ready-to-install solution. We offer a genuine, used OEM PCM, part number 16266645, that is professionally programmed with the latest GM software updates specifically for your vehicle’s VIN. This critical programming step ensures proper communication between all vehicle systems, restoring the original performance and efficiency you expect from your truck.
From the Diagnostic Bay
We had a ’99 Silverado 1500 in the shop that was driving the owner crazy. It had a random misfire, would sometimes refuse to start, and the transmission shifted harshly. He had already replaced the spark plugs, wires, and even the fuel pump. The symptoms all pointed to a failing PCM. Before swapping the module, we did our due diligence and checked the main power and ground connections. We found the main engine-to-chassis ground strap near the firewall was corroded and brittle. After cleaning the contact points and replacing the strap, all the symptoms vanished. It’s a powerful reminder: always verify the basics like power and grounds before condemning an expensive electronic module. A faulty PCM can cause these issues, but so can a ten-dollar ground strap.
Common Symptoms of a Failing PCM
A failing PCM can manifest in various ways, often mimicking other component failures. If your vehicle is experiencing several of the following issues, it’s a strong indicator that your engine computer may need replacement. Here are the most common signs to watch for:
- ✔ No-Start or Intermittent Starting: The engine cranks but won’t start, or starts unreliably.
- ✔ Check Engine Light: The light is on, often with communication-related trouble codes (U-codes) or multiple, seemingly unrelated sensor codes.
- ✔ Poor Engine Performance: Noticeable loss of power, hesitation during acceleration, and a significant drop in fuel economy.
- ✔ Rough Idle or Stalling: The engine idles erratically or stalls unexpectedly, either while driving or at a stop.
- ✔ Erratic Transmission Shifting: The transmission may shift harshly, slip between gears, or get stuck in one gear (limp mode).
- ✔ Failed Emissions Test: Inability to pass smog or emissions testing due to PCM-related faults.
Why Our VIN-Programmed 1998-1999 Savana PCM is the Right Choice
Replacing the PCM on these GM vehicles isn’t as simple as swapping a box. The module must be correctly calibrated for your vehicle’s specific engine, transmission, and options. Our service eliminates the guesswork and the need for expensive dealership programming. We handle the complex part for you. By providing us with your Vehicle Identification Number (VIN) at checkout, you receive a module that is a direct-fit, plug-and-play solution. This used, OEM unit has been thoroughly inspected and is flashed with the most current GM calibrations, often resolving issues that were present even when the vehicle was new. This is the most reliable and cost-effective way to get your truck back on the road and running smoothly.
Installation is Straightforward
Physically replacing the PCM is typically a simple process. It’s located in the engine bay (often on the driver’s side) and is held in by a few bolts with several large electrical connectors. After swapping the module, you will need to perform a security relearn procedure, often called the VATS or Passlock relearn. This procedure syncs the new PCM with your vehicle’s anti-theft system and is required for the engine to start. It’s a simple process that you can do yourself in about 30 minutes with no special tools required.
Frequently Asked Questions
What do I need to do after I purchase this PCM?
After you place your order, you must provide us with your vehicle’s 17-digit VIN. We cannot program and ship the module without it. You can add the VIN to the notes section at checkout or send it to us in a message.
Is this part truly plug-and-play?
Yes, it is programmed to your VIN and requires no further computer programming. However, you MUST perform the security relearn procedure after installation for the vehicle to start. Instructions for this are widely available online and are simple to follow.
My original part number is different from 16266645. Will this work?
This module is a direct replacement for several part numbers, including 09355699, 16250279, 16258815, and more. Please check the extensive compatibility list in the description to confirm it fits your specific make, model, and engine.
Do I need to return my old PCM?
No, there is no core charge for this part. You can keep or dispose of your old module.
Will this fix my transmission shifting problems?
In many cases, yes. The PCM controls both the engine and the transmission. If the transmission’s electronic controls are malfunctioning due to a faulty PCM, this replacement will resolve those shifting issues.
Is this a new part?
No, this is a high-quality, tested, used OEM part sourced from a salvaged vehicle. This ensures OEM reliability and perfect fitment, combined with our professional programming service.