Restore Peak Performance to Your GM Truck or Van
As a technician with over two decades of experience under the hood, I’ve seen firsthand how a failing Powertrain Control Module (PCM) can turn a reliable workhorse into a source of constant frustration. If your 1999-2000 GMC Sierra 1500 or other compatible GM vehicle is experiencing baffling issues like stalling, erratic shifting, or a persistent Check Engine Light, the problem often lies with the vehicle’s electronic brain. This isn’t just a replacement part; it’s a direct-fit, reliable solution to get your truck running right again.
We take the guesswork and dealer-level expense out of the equation. This PCM, part number 21811787, is professionally programmed with the latest official GM software updates specifically for your vehicle. All we need is your Vehicle Identification Number (VIN) at checkout. This ensures that when the module arrives, it communicates flawlessly with your truck’s engine, transmission, and other systems, restoring the smooth operation and efficiency you depend on.
A Technician’s Notebook: The Misleading Fuel Pump
I remember a 2000 Sierra 1500 that came into the shop with a classic no-start condition. The owner had already replaced the fuel pump, convinced that was the issue. When it still wouldn’t fire, he brought it to us. A quick scan showed no communication with the PCM. After checking the power and ground circuits to the module, we found they were solid. The culprit? A failed driver circuit inside the original PCM. It couldn’t command the fuel pump relay to activate. We installed a VIN-programmed module just like this one, performed the security relearn, and the truck fired up on the first try. It’s a common scenario that highlights why correctly diagnosing the PCM is crucial.
Is Your Truck Showing These Telltale Signs?
A failing PCM can manifest in numerous ways. If you’re experiencing any of the following, a faulty module could be the root cause. This isn’t just about a light on the dash; it’s about the core drivability and safety of your vehicle.
- ✔ Unexplained Check Engine Light illumination
- ✔ Stalling or cutting out while driving
- ✔ Harsh or erratic automatic transmission shifting
- ✔ A no-start condition where the engine cranks but won’t fire
- ✔ Noticeable decrease in fuel economy
- ✔ Communication error codes, such as the dreaded P0601 (Internal Control Module Memory Check Sum Error) or P0606 (ECM/PCM Processor Fault)
- ✔ Failure to pass state emissions testing
A Straightforward Guide to Installation
Replacing the PCM on these GM trucks is a job most DIYers can handle with basic tools. Our pre-programmed module makes it even simpler. Here’s a typical process:
- Safety First: Always disconnect the negative terminal from your vehicle’s battery and secure it away from the post.
- Locate the Module: On most 1999-2000 Sierra/Silverado models, the PCM is located in the engine bay on the driver’s side, often under or near the battery tray.
- Disconnect and Remove: Carefully unclip and remove the electrical harness connectors. They have locking tabs, so be gentle. Then, unbolt the module from its mounting bracket.
- Install the New PCM: Mount the new module securely in the bracket and firmly reconnect the electrical harnesses until they click into place.
- Reconnect Battery: Re-attach the negative battery terminal.
- Perform Security Relearn: This is a critical step. You will need to perform the vehicle’s anti-theft relearn procedure (Passlock/VATS). This typically involves turning the key to ‘ON’ for 10-15 minutes, then ‘OFF’, and repeating the cycle two more times. This syncs the new PCM with your vehicle’s security system.
Verified Vehicle Compatibility
This module is a direct replacement for service numbers 16263494, 16265035, and 8162634940. Please verify your part number and check the extensive fitment list below to ensure this is the correct component for your vehicle.
CHEVROLET 2500 PICKUP 00 Electronic Control Module; gasoline (LH front engine compartment)
EXPRESS 1500 VAN 00 Electronic Control Module; (LH rear engine compartment)
EXPRESS 2500 VAN 00 Electronic Control Module; (LH rear engine compartment), gasoline
EXPRESS 3500 VAN 00 Electronic Control Module; (LH rear engine compartment), gasoline
SAVANA 1500 VAN 01-02 Electronic Control Module; (LH rear engine compartment), ID 16263494
ASTRO 00-01 Electronic Control Module; (LH front by battery), ID 16263494
GMC 3500 PICKUP 00 Electronic Control Module; gasoline (LH front engine compartment)
EXPRESS 2500 VAN 01-02 Electronic Control Module; (LH rear engine compartment), gasoline, ID 16263494
S10/S15/SONOMA 99-00 Electronic Control Module; (RH front engine compartment), 4.3L
SAVANA 1500 VAN 00 Electronic Control Module; (LH rear engine compartment)
ASTRO 99 Electronic Control Module; (LH front by battery), (4.3L), ID 16263494
ISUZU HOMBRE 99-00 Electronic Control Module; (RH front engine compartment), 4.3L (6 cylinder)
SAFARI (GMC) 99-01 Electronic Control Module; (LH front by battery), ID 16263494
SAVANA 3500 VAN 01-02 Electronic Control Module; (LH rear engine compartment), gasoline, ID 16263494
EXPRESS 1500 VAN 99 Electronic Control Module; (LH rear engine compartment), ID 16263494
GMC 1500 PICKUP 99 Electronic Control Module; 5.0L, (LH engine compartment), ID 16263494
BLAZER S10/JIMMY S15 98 Electronic Control Module; (RH front engine compartment), w/build date opt ZN4
GMC 1500 PICKUP 99 Electronic Control Module; 5.7L, (LH engine compartment), ID 16263494
SAVANA 3500 VAN 99 Electronic Control Module; (LH rear engine compartment), gasoline, ID 16263494
SAVANA 3500 VAN 00 Electronic Control Module; (LH rear engine compartment), gasoline
TAHOE 00 Electronic Control Module; Classic style (LH front engine compartment)
YUKON 99 Electronic Control Module; (LH engine compartment), ID 16263494
ESCALADE 99 Electronic Control Module; (LH front engine compartment), ID 16263494
ESCALADE 00 Electronic Control Module; (LH front under battery)
EXPRESS 2500 VAN 99 Electronic Control Module; (LH rear engine compartment), gasoline, ID 16263494
S10/S15/SONOMA 98 Electronic Control Module; 6-262 (4.3L), w/build date opt ZN4
YUKON 00 Electronic Control Module; (LH front under battery), Denali
BRAVADA 98 Electronic Control Module; (6-262, 4.3L), w/build date opt ZN4
CHEVROLET 3500 PICKUP 00 Electronic Control Module; gasoline (LH front engine compartment)
ENVOY 99-00 Electronic Control Module; (RH front engine compartment)
EXPRESS 1500 VAN 01-02 Electronic Control Module; (LH rear engine compartment), ID 16263494
EXPRESS 3500 VAN 99 Electronic Control Module; (LH rear engine compartment), gasoline, ID 16263494
GMC 3500 PICKUP 99 Electronic Control Module; gasoline (LH front engine compartment), ID 16263494
ISUZU HOMBRE 98 Electronic Control Module; 4.3L (6 cylinder), w/extended build date opt ZN4
SIERRA 1500 PICKUP 99-00 Electronic Control Module; (LH front under battery), 6 cylinder
SAVANA 2500 VAN 00 Electronic Control Module; (LH rear engine compartment), gasoline
SUBURBAN 1500 99 Electronic Control Module; gasoline (LH front engine compartment), ID 16263494
CHEVROLET 1500 PICKUP 99 Electronic Control Module; 5.7L, (LH engine compartment), ID 16263494
EXPRESS 3500 VAN 01-02 Electronic Control Module; (LH rear engine compartment), gasoline, ID 16263494
GMC 2500 PICKUP 00 Electronic Control Module; gasoline (LH front engine compartment)
SILVERADO 1500 PICKUP 99-00 Electronic Control Module; (LH front under battery), 6 cylinder
SUBURBAN 2500 99 Electronic Control Module; gasoline (LH front engine compartment), ID 16263494
BLAZER S10/JIMMY S15 99-00 Electronic Control Module; (RH front engine compartment)
CHEVROLET 3500 PICKUP 99 Electronic Control Module; gasoline (LH front engine compartment), ID 16263494
SAVANA 1500 VAN 99 Electronic Control Module; (LH rear engine compartment), ID 16263494
TAHOE 99 Electronic Control Module; gasoline (LH front engine compartment), ID 16263494
BRAVADA 99-00 Electronic Control Module; (RH front engine compartment)
CHEVROLET 1500 PICKUP 99 Electronic Control Module; 5.0L, (LH engine compartment), ID 16263494
SAVANA 2500 VAN 99 Electronic Control Module; (LH rear engine compartment), gasoline, ID 16263494
SAVANA 2500 VAN 01-02 Electronic Control Module; (LH rear engine compartment), gasoline, ID 16263494
ENVOY 98 Electronic Control Module; (RH front engine compartment), w/build date opt ZN4
GMC 2500 PICKUP 99 Electronic Control Module; gasoline (LH front engine compartment), ID 16263494
Frequently Asked Questions
Why do you need my VIN?
Your VIN is essential for us to program the 1999-2000 Sierra 1500 PCM with the exact software and calibrations for your truck’s specific engine, transmission, and options. This ensures perfect compatibility and performance, just like a module from the factory.
Is this a simple plug-and-play installation?
It is very close. The module is programmed to your VIN, so no dealer visit is needed for software flashing. However, after physical installation, you must perform the vehicle’s security relearn procedure to sync the new PCM to your keys. This is a simple process that you can do yourself in about 30 minutes.
Will this fix my check engine light?
If the check engine light is caused by an internal PCM failure (like codes P0601, P0606) or a faulty component driver within the module, then yes, this will resolve the issue. It’s important to ensure the problem isn’t an external sensor or wiring issue before replacing the PCM.
What if my original part number is not listed?
The listed part numbers (16263494, 16265035, etc.) are the most common service numbers for this hardware. If your number is different, please contact us with your VIN and original part number. We can verify compatibility for you.
Do I need to send my old PCM back?
No core charge is required for this module. You can keep or responsibly dispose of your old part, making the process faster and more convenient for you.