Restore Peak Performance to Your GM Truck or SUV
If you’re dealing with frustrating issues like a persistent check engine light, poor fuel economy, stalling, or a no-start condition, a failing Powertrain Control Module (PCM) is often the culprit. As a technician with over two decades of experience under the hood, I’ve seen firsthand how a faulty PCM can cripple an otherwise solid vehicle. This isn’t just a part; it’s the central computer of your engine and transmission, and when it fails, nothing works right. This direct-fit replacement PCM is the reliable, straightforward solution to get your vehicle running smoothly again.
We take the guesswork and hassle out of the repair. Unlike sourcing a part from a salvage yard, this module comes professionally programmed with the latest GM software updates, specifically matched to your vehicle using your VIN. This means no expensive trips to the dealership for flashing or programming. It arrives at your door ready for installation, saving you time and money.
A Technician’s Notebook: The Intermittent No-Start Nightmare
I remember a 1999 GMC Jimmy S15 that came into the shop on a tow truck. The owner was at his wit’s end. The truck would run fine for weeks, then suddenly refuse to start. No spark, no fuel injector pulse. He had replaced the fuel pump, ignition coil, and crank sensor, but the problem kept coming back. After confirming power and ground to the PCM, my diagnostic scanner kept losing communication with it during cranking. This is a classic sign of internal failure. We installed a pre-programmed 1998-2000 Envoy PCM (the same unit used in the Jimmy), and the problem was solved instantly. The internal circuitry, specifically the processor, was failing under load—a common issue in these older modules.
Is Your Vehicle Showing These Symptoms?
A failing PCM can cause a wide range of problems. If you’re experiencing any of the following, this module is likely the solution you need:
- ✔ Check Engine Light (CEL) is on with codes like P0601, P0602, P0604, or P0606
- ✔ Engine stalling or shutting off while driving
- ✔ Intermittent or complete no-start condition
- ✔ Harsh or erratic transmission shifting
- ✔ Noticeable drop in fuel economy
- ✔ Communication errors with diagnostic scan tools
- ✔ Failure to pass emissions testing
A Straightforward Guide to Your 1998-2000 Envoy PCM Installation
Installing your new computer is a job most DIYers can handle in under an hour with basic hand tools. Just follow these steps 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 any accidental reconnection.
- Locate the PCM: On most compatible vehicles like the Envoy, S10/Sonoma, and Blazer/Jimmy, the PCM is located in the engine bay, typically on the right-hand (passenger) side fender well. On Express/Savana vans, it’s often in the left rear of the engine compartment.
- Disconnect the Connectors: Carefully unplug the wiring harness connectors from the old module. These usually have a locking tab or lever that needs to be released. Inspect the connectors for any corrosion or damage.
- Remove the Old Module: Unbolt the old PCM from its mounting bracket. Keep the hardware, as you may need it to install the new unit.
- Install the New PCM: Mount your new, pre-programmed PCM onto the bracket and secure it with the original hardware.
- Reconnect Everything: Firmly plug the wiring harnesses into the new module until they click into place. Reconnect your vehicle’s negative battery terminal.
- Final Step: In some cases, a security relearn procedure may be necessary. This can typically be done without special tools by cycling the key. Your vehicle’s service manual will have the specific instructions.
Verified Vehicle Compatibility
This module is a direct replacement for part numbers 16263494, 16265035, 8162634940, and 21811787. It is guaranteed to fit the following models, but please verify your part number or contact us with your VIN to ensure a perfect match.
– ASTRO/SAFARI (99-01) 4.3L
– BLAZER/JIMMY/ENVOY/BRAVADA (98-00) 4.3L
– S10/SONOMA/HOMBRE (98-00) 4.3L
– EXPRESS/SAVANA 1500/2500/3500 (99-02) Gas Engines
– C/K PICKUP 1500/2500/3500 (99-00) Gas Engines
– SILVERADO/SIERRA 1500 (99-00) 6-Cylinder
– SUBURBAN 1500/2500 (99) Gas Engines
– TAHOE/YUKON (99-00) Gas Engines
– ESCALADE (99-00)
*Note: Some 1998 models require build date option ZN4. Please check your service parts sticker.*
Frequently Asked Questions
Frequently Asked Questions
Do I need to do anything after I buy it?
Yes. After your purchase, you must send us your vehicle’s 17-digit VIN (Vehicle Identification Number). We cannot ship your module until we have this information, as we use it to program the unit specifically for your vehicle.
Is this a simple plug-and-play installation?
Absolutely. Because we program the module to your VIN, it’s ready to install right out of the box. In most cases, you will not need any additional programming or trips to a mechanic. Some vehicles may require a simple security relearn procedure, which is detailed in your owner’s manual.
How do I find my original part number?
Your original part number is printed on a sticker on the PCM itself. You can cross-reference it with the numbers listed here (16263494, 16265035, etc.) to confirm compatibility.
Will this fix my transmission shifting problems?
In many cases, yes. The PCM controls both engine and transmission functions. If the module is failing, it can send incorrect signals to the transmission, causing hard shifts, slipping, or delayed engagement. Replacing a faulty PCM often resolves these issues.
What if my vehicle isn’t on the fitment list?
The provided list is extensive but may not cover every single application. The best way to ensure compatibility is to match the part number on your existing module. If you’re still unsure, please contact us with your VIN, and our experts will verify the correct fitment for you.