Restore Your GM Truck’s Core Performance
If your truck or SUV is suddenly stalling, refusing to start, or throwing a check engine light that won’t go away, the problem often lies with the Powertrain Control Module (PCM). As a technician with over 20 years of experience, I’ve seen firsthand how a failing PCM can cause a cascade of frustrating, hard-to-diagnose issues. This isn’t just a part; it’s the brain of your engine, responsible for everything from fuel mixture and spark timing to transmission shifting. A faulty one can leave you stranded.
This listing is for a reliable, tested, and pre-programmed engine computer, compatible with part number 09366810 and many others. We take a quality used OEM unit and flash it with the latest official GM software tailored specifically to your vehicle’s VIN. This means you get a component that’s ready for installation right out of the box, saving you from a costly trip to the dealership for programming.
Case Study: The Intermittent Stall
A customer brought in a ’98 GMC Jimmy S15—a vehicle that shares its core electronics with the Envoy—with a maddening problem. It would run perfectly for days, then suddenly die at a stoplight and refuse to restart for 10-15 minutes. There were no consistent trouble codes, just a history of random communication errors. After checking all the usual suspects like the fuel pump and ignition system, we hooked up a scope to the PCM’s power and ground circuits. We found that the internal voltage regulation was dropping out intermittently when the module got hot. We swapped in a pre-programmed PCM just like this one, and the problem was solved instantly. It’s a classic example of how a failing 1998 Envoy PCM can mimic other, more expensive problems.
Is Your Vehicle Showing These Signs of PCM Failure?
A failing engine computer can manifest in several ways. If you’re experiencing any of the following, a faulty PCM is a likely culprit:
- ✔ Check Engine Light is on with codes like P0601 (Internal Memory Error), P0605 (ROM Error), or U-series communication codes.
- ✔ The engine cranks but refuses to start.
- ✔ Unexplained drops in fuel economy.
- ✔ Harsh or erratic automatic transmission shifting.
- ✔ The vehicle stalls for no apparent reason, especially after warming up.
- ✔ Misfires or rough idling that can’t be traced to plugs, wires, or coils.
A Straightforward Guide to Installation
One of the best parts about our VIN-programmed modules is the ease of installation. While professional installation is always an option, this is a job many DIYers can handle with basic tools.
- Safety First: Always disconnect the negative terminal from your vehicle’s battery before working on any electronic components.
- Locate the PCM: On most of these GM trucks and SUVs, including the 1998 Envoy, the PCM is located in the engine compartment, often on the driver’s or passenger’s side fender well or firewall. It’s a metal box with several large wiring harness connectors.
- Disconnect the Harnesses: Carefully release the locking tabs on the electrical connectors and pull them straight out from the module. Avoid pulling on the wires themselves.
- Remove the Old Module: Unbolt the PCM from its mounting bracket. There are typically two or three bolts holding it in place.
- Install the New PCM: Mount your new, pre-programmed PCM onto the bracket and securely fasten the bolts.
- Reconnect Everything: Plug the wiring harnesses back into the new module until they click firmly into place. Reconnect your negative battery terminal.
- Security Relearn (If Needed): On these GM vehicles, you may need to perform a simple security relearn procedure. Typically, this involves turning the key to the ‘ON’ position for 10-15 minutes, then ‘OFF’ for 10 seconds, and repeating this two more times before starting the engine. This allows the vehicle’s security system to recognize the new PCM.
Verified Vehicle Compatibility
This module is a direct replacement for service ID 09355699 and part number 09366810. It is guaranteed to fit the following vehicles. Please match your part number or vehicle to this list to ensure proper fitment.
CHEVROLET 2500 PICKUP 98-99 (Gasoline)
CHEVROLET 3500 PICKUP 98-99 (Gasoline)
GMC 1500 PICKUP 98-99 (Gasoline)
GMC 2500 PICKUP 98-99 (Gasoline)
GMC 3500 PICKUP 98-99 (Gasoline)
ASTRO 98
BLAZER S10/JIMMY S15 98 (w/o build date opt ZN4)
BRAVADA 98 (w/o build date opt ZN4)
ESCALADE 99
ENVOY 98 (w/o build date opt ZN4)
EXPRESS 1500 VAN 98-99
EXPRESS 2500 VAN 98-99 (Gasoline)
EXPRESS 3500 VAN 98-99 (Gasoline)
ISUZU HOMBRE 98 (4.3L, w/o extended build date opt ZN4)
S10/S15/SONOMA 98 (4.3L, w/o build date opt ZN4)
SAFARI (GMC) 98
SAVANA 1500 VAN 98-99
SAVANA 2500 VAN 98-99 (Gasoline)
SAVANA 3500 VAN 98-99 (Gasoline)
SUBURBAN 1500 98-99 (Gasoline)
SUBURBAN 2500 98-99 (Gasoline)
TAHOE 98-99 (Gasoline)
YUKON 98-99
Frequently Asked Questions
Frequently Asked Questions
How do I provide my VIN for programming?
After you complete your purchase, simply send us a message with your 17-digit Vehicle Identification Number (VIN). We will program the module before shipping it to you.
Is this a new part?
No, this is a high-quality, fully tested used OEM part sourced from a salvaged vehicle. This allows us to offer a reliable and affordable solution compared to a new dealership part.
Will I need to do any programming myself?
No. The main programming is done by us before shipment. The only potential step you might need to perform is a simple, no-tool security relearn procedure, which we’ve outlined in the installation guide.
What if my original part number doesn’t match 09366810 exactly?
This PCM is a direct replacement for several part numbers, including 09355699, 16266645, 16250279, and 16258815. As long as your vehicle is on the compatibility list, this module will work.
What tools are required for installation?
You’ll typically only need basic hand tools, such as a socket set and a ratchet, to remove the mounting bolts and disconnect the battery. No special electronic tools are required.