Is your 1999 or 2000 Chevrolet Silverado or GMC Sierra running poorly, shifting erratically, or showing a persistent check engine light? These are classic signs of a failing Powertrain Control Module (PCM), the central computer that manages your truck’s engine and transmission performance. Don’t let a faulty module keep you off the road. This direct-fit replacement PCM, part number 16265035, is the reliable solution to restore your vehicle’s original performance and efficiency.
We take the guesswork and high costs out of the equation. Unlike a generic part from a local store, each module we ship is professionally programmed with the latest GM software updates specifically for your vehicle. All we need is your Vehicle Identification Number (VIN) at checkout. This ensures that when the part arrives, it’s ready to integrate seamlessly with your truck’s systems, managing everything from fuel mixture and ignition timing to transmission shift points just as the factory intended. This critical programming step saves you a costly trip to the dealership and eliminates compatibility headaches.
From the Diagnostic Bay
We had a 2000 Sierra 1500 with the 4.3L V6 come into the shop with a bizarre issue. The owner complained of intermittent stalling at stoplights and a random hard shift from first to second gear, but there were no consistent trouble codes. We checked fuel pressure, sensors, and wiring, but everything seemed fine. On a hunch, we connected a scope to the PCM’s main processor. We found that the processor would occasionally drop voltage internally, causing it to ‘reboot’ for a split second. This was enough to cause the stall or shift issue without logging a permanent code. Replacing the PCM with a correctly programmed unit like this one solved the problem instantly. It’s a reminder that not all PCM failures throw a clear P0601 ‘Internal Memory Error’ code.
Common Symptoms of a Failing GM PCM
If you’re experiencing any of the following issues, a faulty PCM could be the culprit. Replacing your old module with our pre-programmed 1999-2000 Silverado PCM can resolve these problems and get your truck running like new again.
- ✔ Persistent Check Engine Light (CEL) illumination
- ✔ Stored diagnostic trouble codes (DTCs) related to internal module failure (e.g., P0601, P0606)
- ✔ Poor or erratic automatic transmission shifting
- ✔ Engine stalling, stumbling, or misfiring
- ✔ Noticeable decrease in fuel economy
- ✔ Failure to pass emissions testing
- ✔ Complete no-start condition where the engine cranks but won’t fire
This Powertrain Control Module is a vital component, acting as the brain for your entire powertrain. It constantly analyzes data from sensors throughout your vehicle to make real-time adjustments for optimal performance, emissions, and fuel efficiency. When it begins to fail, the symptoms can be widespread and confusing. Our solution provides a fully tested and properly prepared module that acts as a direct replacement for service numbers 16265035 and 16263494, ensuring a reliable and lasting repair.
Installation is straightforward for a DIY mechanic with basic tools. The module is typically located in the engine bay on the driver’s side. After disconnecting the battery, simply unbolt the old unit, disconnect the wiring harnesses, and install the new one in its place. Once installed, you will need to perform a security relearn procedure (often called a CASE relearn or Passlock relearn), which pairs the new PCM to your vehicle’s anti-theft system. This procedure is simple and can be done without special tools, typically involving a series of key cycles.
Frequently Asked Questions
Why do you need my VIN?
Your Vehicle Identification Number (VIN) is essential because it allows us to program the PCM with the exact software calibration file for your truck’s specific engine, transmission, and emissions equipment. This ensures perfect compatibility and performance without needing a trip to the dealer.
Is this part difficult to install?
Installation is generally simple for those with basic mechanical skills. It involves disconnecting the battery, unplugging the electrical connectors, and removing a few bolts. The most important step after installation is the security relearn procedure, which can be done at home and instructions are widely available online.
Will this fix my check engine light?
If the check engine light is caused by a faulty PCM (e.g., internal processor error codes), then yes, this replacement module will resolve the issue. However, if the light is on due to a bad sensor or other mechanical problem, you will still need to diagnose and fix that separate issue.
Is this a plug-and-play part?
Because we program it to your VIN, it is as close to plug-and-play as possible. However, you will still need to perform the vehicle’s security relearn procedure after installation to sync the new computer with your anti-theft system. This is a mandatory step for all replacement PCMs on these vehicles.
What vehicles does this PCM fit?
This PCM fits a wide range of 1998-2002 GM trucks and vans, including the Chevrolet Silverado, Express, Tahoe, and S10, as well as the GMC Sierra, Savana, Yukon, and Sonoma. Please refer to the detailed fitment list on this page to confirm compatibility with your specific model and engine.