Restore Peak Performance to Your GM Vehicle
Is your 1998-1999 Chevy Express 2500, or another compatible GM truck or van, suffering from mysterious and frustrating issues? Problems like a persistent check engine light, poor engine performance, erratic shifting, or even a no-start condition can often be traced back to a single, critical component: the Powertrain Control Module (PCM). As the central computer for your engine and transmission, a failing PCM can disrupt countless vehicle functions, making diagnosis a nightmare. This genuine, used OEM engine computer, part number 09366810, is the reliable and cost-effective solution to get your vehicle back on the road and running smoothly.
From the Diagnostic Bay
I once had a ’99 GMC Suburban towed in that had stumped two other shops. The complaint was intermittent stalling and a complete no-start when hot. The owner had already replaced the fuel pump and crank sensor. My scan tool would intermittently lose communication with the PCM, a classic sign of a failing computer. Before condemning the module, I always check the basics. I inspected the main PCM connectors for corrosion and tested the power and ground circuits directly at the module. One of the main ground wires showed high resistance when I wiggled the harness. It turned out the ground point on the engine block was corroded under the bolt head. After cleaning the connection point to bare metal, the Suburban ran perfectly. Always verify your main power and ground connections before replacing a PCM—it can save you time and money!
Diagnosing a Faulty 1998-1999 Express 2500 PCM
The PCM is the brain of your vehicle’s operation. When it begins to fail, the symptoms can be widespread and confusing. If you’re experiencing any of the following issues, a faulty engine computer may be the culprit. This replacement module is designed to resolve these common problems and restore your vehicle’s factory operation.
Common Symptoms of PCM Failure
- ✔ Check Engine Light: The light may be on with codes related to internal module failure or communication errors (U-codes).
- ✔ No-Start or Intermittent Start: The engine may crank but fail to start, or start unreliably.
- ✔ Poor Engine Performance: Noticeable loss of power, rough idling, stalling, or hesitation during acceleration.
- ✔ Decreased Fuel Economy: A failing PCM can’t properly manage the air-fuel mixture, leading to wasted gas.
- ✔ Transmission Issues: Harsh, delayed, or incorrect gear shifting, as the PCM also controls transmission functions.
- ✔ Failed Emissions Test: The vehicle may not be able to pass an emissions inspection due to PCM-related faults.
- ✔ No Communication: A diagnostic scan tool may be unable to connect or communicate with the PCM.
The Critical Advantage: VIN-Specific Programming
Simply swapping an engine computer from another vehicle will not work. Each PCM is programmed with specific software and a Vehicle Identification Number (VIN) that is unique to the vehicle it came from. Our service eliminates this problem. When you purchase this module, we will flash it with the latest official GM software updates and program it specifically to your vehicle’s VIN. This ensures complete compatibility with your engine, transmission, and all factory options. This plug-and-play solution saves you an expensive trip to the dealership for programming, getting you back on the road faster.
Installation Process
After receiving your pre-programmed PCM, the physical installation is straightforward. Disconnect the battery, locate your old PCM (typically in the engine bay), unplug the electrical connectors, and swap the module. After installation, you will need to perform a simple security relearn procedure (often called VATS or Passlock) to sync the new computer with your vehicle’s anti-theft system. This procedure does not require special tools and typically involves a sequence of turning the key on and off. We can provide instructions for this simple process.
This module is a direct replacement for multiple part numbers, including 09355699, 16266645, 16250279, 16258815, and 9366810. It fits a wide variety of 1998-1999 GM trucks, vans, and SUVs like the Chevrolet and GMC 1500/2500/3500 pickups, Suburban, Tahoe, Yukon, Astro, Safari, and more. Please verify your part number or consult the detailed fitment list to ensure compatibility.
Frequently Asked Questions
How do I provide my vehicle’s VIN?
After placing your order, please send us your 17-digit VIN by replying to the order confirmation email or by adding it to the ‘notes’ section during checkout. We cannot program and ship the module without your VIN.
Is this a difficult part to install myself?
The physical installation is typically very simple, requiring only basic hand tools to access and unbolt the old module. The most important step after installation is performing the security relearn procedure, which allows the engine to start. Instructions for this process are readily available and easy to follow.
Will this computer need any other programming at the dealer?
No. We pre-program the PCM to your VIN with the latest GM calibrations, so it is ready to install right out of the box. This saves you the time, hassle, and expense of a dealership visit for programming.
What is a CASE Relearn and will I need one?
A Crankshaft Variation Relearn (CASE Relearn) synchronizes the PCM with the crankshaft position sensor. After installation, you may have a Check Engine Light with code P1336. While the vehicle will run and drive fine, this code can only be cleared by performing a CASE relearn with a compatible bi-directional scan tool. Many local repair shops can perform this service for a small fee.
Is this a new part?
No, this is a genuine, used OEM part sourced from a salvaged vehicle. Each unit is thoroughly inspected and tested to ensure full functionality before being programmed and shipped.