Restore Your Truck’s Performance and Reliability
Is your trusty GMC 1500 or another GM vehicle suddenly giving you headaches? If you’re dealing with a persistent Check Engine Light, unpredictable stalling, rough idling, or poor fuel economy, the problem might be deeper than a simple sensor. As the central computer of your vehicle, the Powertrain Control Module (PCM) is responsible for managing everything from fuel mixture and ignition timing to transmission shifting. When it fails, it can create a cascade of frustrating and hard-to-diagnose issues. This is the definitive solution: a replacement 1999 GMC 1500 PCM, professionally programmed with the latest GM software updates specifically for your vehicle.
We take the guesswork and high dealership costs out of the equation. Simply provide us with your Vehicle Identification Number (VIN) after your purchase, and our experts will flash this module to match your vehicle’s exact specifications. This ensures seamless communication between all your vehicle’s systems, restoring the performance and dependability you count on. Forget about expensive towing or scheduling appointments for programming—this module arrives ready for a straightforward installation.
From the Diagnostic Bay: The Ghost in the Machine
I remember a 1999 Chevy Silverado that came into my shop a few years back. The owner had spent a fortune replacing the throttle position sensor, the mass airflow sensor, and even a couple of oxygen sensors trying to chase down an intermittent stalling problem and a P0601 (Internal Control Module Memory Check Sum Error) code that kept coming back. He was at his wit’s end. We hooked up our pro-level scanner and saw erratic data streams across the board—a classic sign the PCM itself was the culprit. The internal processor was failing, sending faulty signals that made other good components look bad. We installed a VIN-programmed PCM just like this one, and the truck ran perfectly. It’s a common scenario with these older GM vehicles, and a new PCM is often the one true fix.
Is Your Vehicle Showing These Telltale Signs?
- ✔ Persistent Check Engine Light with codes like P0601, P0602, P0604, or P0606.
- ✔ Unexplained drop in fuel efficiency (MPG).
- ✔ Harsh or erratic automatic transmission shifting.
- ✔ Engine cranks but refuses to start (no-start condition).
- ✔ Stalling for no apparent reason, either at idle or while driving.
- ✔ Failure to pass an emissions or smog test.
- ✔ Rough or unstable engine idle.
Your Straightforward Installation Guide
Installing your new 1999 GMC 1500 PCM is a manageable job for a DIYer with basic tools. While the exact location can vary by model, here is a general guide.
- Safety First: Always disconnect the negative terminal from your vehicle’s battery and wait at least 10 minutes to allow the system to fully discharge.
- Locate the PCM: On most GM trucks and SUVs from this era, the PCM is in the engine compartment, typically on the driver’s side fender well or near the battery. On vans, it’s often in the LH rear engine compartment. Check your specific model for its location.
- Disconnect the Connectors: Carefully unclip the wiring harness connectors from the old PCM. There are usually two or three large multi-pin connectors. They have locking tabs that need to be released before you can pull them off.
- Remove the Old Module: Unbolt the old PCM from its mounting bracket. It’s typically held in place by a few small bolts (often 10mm).
- Install the New Module: Mount your new, pre-programmed PCM onto the bracket and securely fasten the bolts.
- Reconnect Everything: Firmly plug the wiring harness connectors into the new module until they click into place. Reconnect your vehicle’s negative battery terminal.
- Final Step: Some vehicles may require a security relearn procedure, which can often be done by cycling the key. Your vehicle is now ready to start.
Verified Compatibility for Your GM Vehicle
This module is a direct replacement for part numbers 16263494, 16265035, 8162634940, and 21811787. It is guaranteed to fit the following models, among others. Please verify your part number or contact us to ensure compatibility.
GMC 1500/2500/3500 PICKUP (99-00)
SIERRA/SILVERADO 1500 PICKUP (99-00)
CHEVROLET EXPRESS 1500/2500/3500 VAN (99-02)
GMC SAVANA 1500/2500/3500 VAN (99-02)
CHEVROLET ASTRO / GMC SAFARI (99-01)
CHEVROLET S10 / GMC SONOMA (98-00)
CHEVROLET BLAZER / GMC JIMMY (98-00)
OLDSMOBILE BRAVADA (98-00)
CADILLAC ESCALADE (99-00)
CHEVROLET TAHOE / GMC YUKON (99-00)
ISUZU HOMBRE (98-00)
…and more. Please check the full fitment list.
Frequently Asked Questions about this 1999 GMC 1500 PCM
Frequently Asked Questions
Why do you need my VIN?
Your VIN (Vehicle Identification Number) is essential for us to program the PCM with the correct factory software for your vehicle’s specific engine, transmission, and options. This ensures it works perfectly right out of the box.
Is this a plug-and-play part?
Yes! Because we pre-program it to your VIN, no further programming is required. In some cases, a simple key-cycle security relearn procedure may be necessary, which does not require special tools.
Will this fix my transmission shifting problems?
If the shifting issues are caused by faulty signals from the PCM, then yes, this will resolve them. The PCM controls transmission shift points, and a failing module is a very common cause of erratic shifting in these vehicles.
What if my original part number is slightly different?
This module replaces several part numbers, including 16263494 and 16265035. As long as your vehicle is on the compatibility list, this module will function correctly once programmed to your VIN.
How do I know for sure my PCM is bad?
The best way is a professional diagnosis. However, common symptoms like a no-start condition with fuel and spark present, multiple unrelated trouble codes, or a specific P0601 code are strong indicators of PCM failure.