Restore Peak Performance to Your GM Truck or Van
If you’re dealing with a frustrating check engine light, poor fuel mileage, erratic shifting, or a no-start condition in your 1999-2000 GMC 3500 Pickup, a failing Powertrain Control Module (PCM) is often the culprit. As the central computer of your vehicle, the PCM governs everything from fuel injection and spark timing to transmission shift points. When it falters, the entire vehicle’s performance suffers. This isn’t just an inconvenience; it’s a problem that affects your truck’s reliability and your peace of mind.
We offer a dependable and straightforward solution. This Powertrain Control Module is not just a replacement part; it’s a fully prepared component, programmed with the latest official GM software updates specifically for your vehicle. Simply provide us with your Vehicle Identification Number (VIN) after purchase, and our technicians will flash the module before it ships. This critical step ensures seamless integration with your truck’s systems, eliminating the need for an expensive trip to the dealership for programming. Get your workhorse back on the road with a reliable, correctly configured 1999-2000 GMC 3500 PCM.
A Technician’s Notebook
I remember a 2000 Chevy Express van that came into the shop with a complaint that stumped two other mechanics. The van would randomly stall at idle, but only when warm. No consistent codes were stored, except for an occasional random misfire. We checked fuel pressure, ignition components, and sensors—all tested fine. On a hunch, I monitored the live data stream from the PCM and noticed the injector pulse width would suddenly drop to zero right before it stalled. After swapping in a known-good, programmed PCM, the problem vanished. The original module had an internal fault, likely a hairline crack in a solder joint that only opened up when it reached a certain temperature. It’s a classic example of how a failing 1999-2000 GMC 3500 PCM (or its equivalent in other GM models) can create ghost-like issues that are impossible to trace with conventional diagnostics.
Is Your Truck Showing These Signs of PCM Failure?
- ✔ Check Engine Light is illuminated with codes like P0601 (Internal Control Module Memory Check Sum Error) or other communication errors.
- ✔ The engine cranks but refuses to start.
- ✔ Noticeable decrease in fuel economy.
- ✔ The transmission shifts harshly, late, or not at all.
- ✔ Stalling, stuttering, or rough idling, especially when the engine is warm.
- ✔ Communication issues with your diagnostic scan tool.
A Straightforward Guide to Installation
Replacing the PCM in these GM trucks is a job most DIYers can handle with basic tools. Our pre-programming service saves you the most complicated step. Follow this general guide for a smooth installation.
- Safety First: Always disconnect the negative terminal from your vehicle’s battery and secure it away from the post to prevent accidental reconnection.
- Locate the Module: On most GMT400 and early GMT800 trucks and vans, the PCM is located in the engine compartment, typically on the driver’s side fender well or near the battery.
- Disconnect Wiring: Carefully release the locking tabs on the large electrical connectors and pull them straight out from the module. Avoid pulling on the wires themselves. There are usually multiple connectors, often color-coded.
- Remove the Old PCM: Unbolt the mounting bracket holding the old PCM in place. It’s typically held by a few 10mm or 13mm bolts. Remove the old unit from the vehicle.
- Install the New PCM: Mount your new, pre-programmed PCM into the bracket and secure the bolts. Reconnect the electrical connectors, ensuring they click securely into place.
- Reconnect Battery: Reattach the negative battery terminal.
- Perform Security Relearn (CRITICAL): Your vehicle’s anti-theft system (PassLock/VATS) needs to sync with the new PCM. Turn the key to the ‘ON’ position (don’t start) for 10-15 minutes, or until the ‘Security’ light on the dash stops flashing and turns off. Turn the key off for 10 seconds, then the vehicle should start. This may need to be repeated up to three times.
Verified Vehicle Compatibility
This module is a direct replacement for part numbers 16263494, 16265035, and 8162634940. It is guaranteed to fit the following vehicles. Please verify your specific model and options before ordering.
CHEVROLET/GMC TAHOE/YUKON/ESCALADE (99-00)
CHEVROLET/GMC SUBURBAN 1500/2500 (99, Gasoline)
CHEVROLET EXPRESS / GMC SAVANA 1500/2500/3500 VAN (99-02, Gasoline)
CHEVROLET ASTRO / GMC SAFARI (99-01)
CHEVROLET S10 / GMC SONOMA (98-00, 4.3L)
CHEVROLET BLAZER / GMC JIMMY / OLDSMOBILE BRAVADA (98-00)
GMC ENVOY (98-00)
ISUZU HOMBRE (98-00, 4.3L)
Note: Some 1998 models require build date option ZN4. Some models require matching the ID number 16263494. Please check your original part.
Frequently Asked Questions About Your New PCM
Frequently Asked Questions
Why do you need my VIN?
Your VIN (Vehicle Identification Number) allows us to program the PCM with the exact software and calibrations your specific vehicle requires. This includes engine size, transmission type, and emissions equipment, ensuring it works perfectly right out of the box.
Is this a plug-and-play part?
Almost. Because we pre-program the module to your VIN, the complex part is done. You will only need to perform a simple security relearn procedure after installation, which takes about 30 minutes and requires no special tools.
Will this fix my check engine light?
If the check engine light is caused by a faulty PCM (e.g., code P0601), then yes, this replacement module will resolve the issue. However, if the light is on for another reason, like a bad oxygen sensor, that issue will still need to be addressed separately.
Can I install this myself?
Absolutely. For someone with basic mechanical skills and common hand tools, this is a very manageable DIY job. Our installation guide above outlines the key steps. The most important part is remembering to disconnect the battery and perform the security relearn.
What is the difference between a PCM and an ECM?
The terms are often used interchangeably. ECM (Engine Control Module) traditionally controlled only the engine. PCM (Powertrain Control Module) is a more modern term for a module that controls both the engine and the automatic transmission. For these vehicles, this module functions as the PCM.