Is Your 1999-2000 Sierra 2500 Running Rough?
If you’re dealing with a frustrating check engine light, bizarre shifting behavior, or an engine that just won’t run right, the problem often points directly to the heart of your truck’s electronics: the Powertrain Control Module (PCM). As a technician with over two decades of experience under the hood of these exact GM trucks, I’ve seen firsthand how a failing PCM can turn a reliable workhorse into a source of constant headaches. It’s the central computer, the brain that manages everything from fuel injection and spark timing to transmission shift points. When it starts to fail, the symptoms can be confusing and widespread.
Diagnosing a Failing PCM: What to Look For
A faulty PCM doesn’t always fail completely at once. Often, the symptoms start small and get progressively worse. Heat, vibration, and moisture—especially from a leaking battery located directly above it in these trucks—can wreak havoc on the delicate internal circuits over time. Here are the classic signs I look for in the shop when a GM truck from this era comes in with electrical gremlins:
- ✔ Unexplained Check Engine Light (CEL) with various communication or sensor codes.
- ✔ Harsh or erratic automatic transmission shifting.
- ✔ Engine stalling, stumbling, or misfiring for no apparent reason.
- ✔ A sudden, significant drop in fuel economy.
- ✔ Complete no-start condition where the engine cranks but won’t fire up.
- ✔ Inconsistent or non-functional dashboard gauges.
- ✔ The security or anti-theft light stays on, preventing the engine from starting.
From the Shop Floor: A Real-World Diagnostic
“A customer’s 2000 Sierra 2500 came in last week with these exact symptoms. It had an intermittent no-start and a P0601 ‘Internal Control Module Memory Check Sum Error’ code that would come and go. We checked all the grounds and power feeds to the PCM—they were perfect. The issue was internal to the module itself. After swapping in a properly programmed PCM, the truck fired up on the first try and all the codes were gone. It’s a classic failure mode for these units after 20+ years of service.”
The Direct-Fit, Programmed Solution
Don’t let a faulty computer sideline your truck. This Powertrain Control Module is the reliable, straightforward solution to restore your vehicle’s performance and dependability. We take all the guesswork and additional expense out of the equation. Unlike a generic part from a salvage yard that would require a costly trip to a dealership for programming, this module arrives at your door ready to install.
The process is simple: After you complete your purchase, you provide us with your truck’s 17-digit Vehicle Identification Number (VIN). Our technicians then use that VIN to flash the module with the latest, most stable software updates directly from GM. This ensures perfect compatibility with your truck’s specific engine, transmission, and options.
Why VIN-Specific Programming is Crucial
Flashing the PCM with the correct software is not just about making it work; it’s about making it work *correctly*. Over the years, manufacturers release software updates to fix bugs and improve vehicle operation. Our programming service ensures your new PCM has these benefits baked in.
- ✔ Corrects common factory drivability issues.
- ✔ Ensures proper communication with all other modules on the vehicle.
- ✔ Calibrates the engine and transmission for optimal performance and efficiency.
- ✔ Resolves many software-related diagnostic trouble codes (DTCs).
Installation & Part Number Confirmation
On the 1999-2000 Sierra 2500, the PCM is located on the driver’s side of the engine bay, typically mounted to a bracket underneath the battery tray. Installation is a matter of disconnecting the battery, removing the old module, and plugging this new one in. Once installed, you may need to perform a security relearn procedure, which is a simple process that can be done without special tools.
This module is a direct replacement for the following GM part numbers:
09354896, 9354896, and 19109040
Please check the part number on your existing module to confirm compatibility. This part is guaranteed to fit the extensive list of GM vehicles detailed in the compatibility chart, restoring your vehicle’s function and getting you back on the road with confidence.