Restore Your Workhorse: The Reliable Fix for Your GM Van or Truck
As a technician with over two decades of experience, I know the frustration when a reliable work vehicle like your 1998-1999 Express 3500 Van starts acting up. Unexplained stalling, a persistent Check Engine Light, and poor performance don’t just cause headaches—they cost you time and money. The Powertrain Control Module (PCM) is the electronic brain of your engine and transmission, and when it fails, it can create a cascade of confusing problems. This isn’t just a part; it’s the solution to getting your vehicle back on the road and running as it should.
This is a genuine, tested OEM PCM, part number 09366810, sourced from a salvaged vehicle. The real value here is our in-house programming service. Before we ship it, we flash the module with the latest official GM software updates, tailored specifically to your vehicle’s VIN. This means you receive a part that is truly plug-and-play, eliminating the need for an expensive trip to the dealership for programming. This is the most direct and cost-effective way to solve complex electronic issues and restore your engine’s original performance and efficiency.
A Technician’s Notebook: The Misleading Sensor Code
I remember a 1999 GMC Sierra coming into the shop with a persistent code for the throttle position sensor (TPS). The owner had already replaced the sensor twice with no luck. The engine would hesitate badly under light acceleration. Instead of just throwing another sensor at it, we hooked up the scope. We found the 5-volt reference signal to the sensor was dropping out intermittently. Tracing it back, the issue wasn’t the sensor or the wiring—it was a failing driver inside the PCM. A new PCM, programmed correctly, solved the problem instantly. It’s a classic case where the symptom (bad sensor reading) points away from the true cause (the failing computer). This highlights why a quality, correctly programmed 1998-1999 Express 3500 PCM is critical.
Is Your GM Truck or Van Showing These Signs?
A failing PCM can manifest in many ways. If you’re experiencing any of the following, a faulty module is a likely culprit:
- ✔ Vehicle will not start or is very difficult to start.
- ✔ Check Engine Light is illuminated with codes like P0601, P0602, P0605, or P0606 (Internal Module Errors).
- ✔ Unexplained drop in fuel economy.
- ✔ Engine stalls, stumbles, or misfires randomly.
- ✔ Harsh or erratic automatic transmission shifting.
- ✔ Failure to pass an emissions/smog test.
- ✔ Communication errors with diagnostic scan tools.
A Straightforward Guide to Installation
Replacing the PCM is a job most DIYers can handle with basic tools. Our pre-programming service saves you the hardest step. Follow this general guide for a smooth installation:
- Safety First: Disconnect the negative terminal from your vehicle’s battery and secure it away from the post.
- Locate the PCM: On most of these GM trucks and vans, the PCM is located in the engine compartment, typically on the driver’s side inner fender or near the battery.
- Disconnect the Old Unit: Carefully unplug the electrical harness connectors. They have locking tabs that need to be released—be gentle to avoid breaking them. Once disconnected, unbolt the module from its bracket.
- Install the New PCM: Bolt your new, pre-programmed PCM into place. Reconnect the electrical harnesses, ensuring they click securely into position.
- Reconnect the Battery: Re-attach the negative battery terminal.
- Perform Security Relearn (If Necessary): For many of these vehicles, you’ll need to perform a simple security relearn procedure so the vehicle recognizes the new PCM. This usually involves turning the key to the ‘ON’ position for 10-15 minutes, then off, and repeating two more times. This allows the anti-theft system to sync with the new module.
Verified Compatibility for a Wide Range of GM Vehicles
This PCM, identified by service number 09366810 or interchange ID 09355699, fits a large family of GM trucks and vans. While this listing is for a 1998-1999 Express 3500 PCM, please check your original part number and the list below to confirm fitment. Providing your VIN at checkout is the best way to guarantee perfect compatibility.
- ✔ Chevrolet/GMC C/K 1500, 2500, 3500 Pickups (1998-1999)
- ✔ Chevrolet/GMC Suburban 1500, 2500 (1998-1999)
- ✔ Chevrolet Tahoe & GMC Yukon (1998-1999)
- ✔ Cadillac Escalade (1999)
- ✔ Chevrolet Express & GMC Savana 1500, 2500, 3500 Vans (1998-1999)
- ✔ Chevrolet Astro & GMC Safari Vans (1998)
- ✔ Chevrolet S10, GMC Sonoma, Oldsmobile Bravada, Isuzu Hombre (1998)
- ✔ Chevrolet Blazer S10, GMC Jimmy S15, GMC Envoy (1998)
Frequently Asked Questions
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 specific vehicle requires. This includes engine size, transmission type, and emissions equipment, ensuring flawless operation right out of the box.
Is this a new part?
No, this is a high-quality, used OEM part that has been thoroughly tested and inspected. We source them from salvaged vehicles, allowing us to offer a reliable, factory-grade component at a significant cost saving compared to a new dealer part.
Will I need to do anything after installing it?
Because we program it to your VIN, no further programming is needed. However, you will likely need to perform a simple security relearn procedure, which can be done without any special tools. Instructions are widely available online or in your vehicle’s service manual.
How do I find my part number?
Your original PCM will have a sticker on it with the service number. It’s crucial to match this number to one of the compatible numbers listed (09366810, 09355699, 16266645, etc.) to ensure physical compatibility before we program it.
Will this fix my vehicle’s problem?
This part corrects issues directly caused by a faulty PCM. While the symptoms listed are common for PCM failure, it’s always best practice to have a proper diagnosis performed by a qualified mechanic to rule out other potential causes like wiring or sensor faults.
What is the benefit of the ‘latest GM updates’?
Over a vehicle’s life, manufacturers often release software updates to improve things like transmission shift points, fuel efficiency, and idle stability. By flashing your replacement PCM with these latest updates, you’re not just replacing a broken part—you’re getting the most refined operational software available for your vehicle.