Restore Your Vehicle’s Performance and Reliability
Is your truck, van, or SUV giving you headaches? A faulty Powertrain Control Module (PCM) can be the hidden cause of some of the most frustrating and difficult-to-diagnose engine problems. As a technician with over two decades of experience, I’ve seen firsthand how a failing PCM can mimic other issues, leading to wasted time and money on unnecessary repairs. This genuine, used OEM PCM, part number 09355699, is the dependable and cost-effective solution to get your vehicle back in top form.
The biggest hurdle with replacing a PCM isn’t the physical installation—it’s the programming. This module solves that problem for you. Before we ship it, we flash it with the latest official GM software updates, tailored specifically to your vehicle using the VIN you provide. This means it arrives at your door ready to install, saving you a costly trip to the dealership and the hassle of coordinating programming. This isn’t just a part; it’s a complete, ready-to-go fix for your 1998 Envoy PCM and many other GM models.
Case Study: A Tricky Diagnosis
A customer brought in a ’99 Suburban that would crank but not start. They had already replaced the fuel pump and filter, but the problem persisted. The scan tool showed no communication with the PCM. After verifying power and ground at the module connectors—a critical first step—we suspected the PCM itself. We connected a test module, and the engine fired right up. The original PCM’s internal driver circuit had failed, a common issue in these units after years of heat cycles. This programmed replacement is the exact fix we used to get that Suburban reliably back on the road for its owner.
Is Your GM Truck or SUV Showing These Signs?
A failing PCM can manifest in various ways. If you’re experiencing any of the following, your engine computer could be the culprit:
- âś” Check Engine Light is on with codes like P0601 (Internal Control Module Memory Check Sum Error) or other communication faults.
- âś” The engine cranks but refuses to start.
- âś” Unexplained stalling or rough idling, especially after warming up.
- âś” Noticeable decrease in fuel economy.
- âś” Harsh or erratic automatic transmission shifting.
- âś” Failure to pass an emissions test.
- âś” No communication with your scan tool.
A Straightforward Guide to Installation
Installing your programmed 1998 Envoy PCM is a job most DIYers can handle with basic tools. Just follow these steps carefully for a smooth replacement.
- 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 of these vehicles, the PCM is located in the engine compartment, typically on the driver’s or passenger’s side fender well or near the battery.
- Disconnect the Connectors: Carefully unlatch and remove the electrical harness connectors from the old module. Inspect them for any corrosion or damaged pins.
- Remove the Old Module: Unbolt the old PCM from its mounting bracket and remove it from the vehicle.
- Install the New PCM: Mount your replacement PCM securely onto the bracket and reconnect the electrical harnesses. Ensure they click firmly into place.
- Reconnect the Battery: Reattach the negative battery terminal.
- Perform Security Relearn: Some GM vehicles of this era require a security relearn procedure to allow the vehicle to start. This simple process can typically be done without special tools by cycling the key. Search for the “GM Passlock Relearn Procedure” for your specific model.
Verified Vehicle Compatibility
This module is a direct replacement for service number 09355699 and is interchangeable with part numbers 16266645, 16250279, 16258815, and 09366810. It is confirmed to fit the following vehicles:
- Astro / Safari (GMC): 1998
- Blazer S10 / Jimmy S15: 1998 (w/o build date opt ZN4)
- Bravada: 1998 (w/o build date opt ZN4)
- Cadillac Escalade: 1999
- Chevrolet / GMC 1500, 2500, 3500 Pickups: 1998-1999 (Gasoline)
- Chevrolet / GMC Suburban 1500, 2500: 1998-1999 (Gasoline)
- Envoy: 1998 (w/o build date opt ZN4)
- Express / Savana 1500, 2500, 3500 Vans: 1998-1999 (Gasoline)
- Isuzu Hombre: 1998 (4.3L, w/o extended build date opt ZN4)
- S10 / S15 / Sonoma: 1998 (4.3L, w/o build date opt ZN4)
- Tahoe / Yukon: 1998-1999 (Gasoline)
Frequently Asked Questions About Your 1998 Envoy PCM
Frequently Asked Questions
Why do you need my VIN?
Your Vehicle Identification Number (VIN) allows us to program the PCM with the exact software and calibrations your vehicle’s specific configuration requires. This ensures proper engine and transmission function, and compatibility with its options.
Is any other programming needed after I install it?
In most cases, no further programming is needed. However, you may need to perform a simple, tool-free “Security Relearn Procedure” (also known as Passlock relearn) to sync the module with your vehicle’s anti-theft system. This typically involves a few cycles of the ignition key.
Is this a new part?
No, this is a thoroughly tested, genuine OEM part sourced from a salvaged vehicle. We guarantee its functionality and back it with our expertise. This provides OEM reliability at a fraction of the cost of a new dealer part.
How do I confirm this is the right part for my vehicle?
The best way is to match the part number on your existing PCM. This module replaces part number 09355699 and several others listed in the description. Verifying the number on your old unit ensures a perfect match.
What’s the difference between a PCM, ECM, and ECU?
The terms are often used interchangeably. PCM (Powertrain Control Module) is most accurate for these vehicles as it controls both the engine and transmission. ECM (Engine Control Module) and ECU (Electronic Control Unit) are more general terms. For this application, they all refer to the same computer.