Restore Your Van’s Brain and Get Back to Work
Is your 1998-1999 Chevrolet Express 3500 Van giving you headaches? If you’re dealing with a frustrating no-start condition, erratic idling, poor fuel mileage, or a persistent Check Engine Light, the problem often points directly to a failing Powertrain Control Module (PCM). As the central computer for your engine and transmission, when the PCM falters, your entire vehicle’s performance suffers. This isn’t just an inconvenience; for a work van, it’s lost time and money.
We offer a dependable and straightforward solution: a tested, genuine OEM PCM with service number 9355699. This isn’t just a part in a box. We flash it with the latest official GM software updates and program it specifically to your van’s Vehicle Identification Number (VIN) before it ships. This crucial step ensures that it communicates perfectly with your vehicle’s specific options and systems, making installation a breeze and eliminating the need for an expensive trip to the dealership for programming.
A Technician’s Notebook: The Intermittent Gremlin
I once had a 1998 Savana 2500 in my bay with an issue that was driving the owner crazy. It would run perfectly for days, then suddenly stall at a stoplight and refuse to restart for an hour. There were no consistent trouble codes, just a history of random communication errors. After checking all the usual suspects—fuel pressure, ignition components, wiring harnesses—I focused on the PCM. On these older GM vans, heat cycles and vibrations can cause microscopic cracks in the PCM’s internal solder joints. We swapped in a VIN-programmed PCM like this one, and the problem vanished instantly. The customer saved hundreds compared to a dealership diagnosis and was back on the road for his delivery business the same day.
Is Your Van Exhibiting These PCM Failure Signs?
A faulty PCM can manifest in numerous ways. If you’re experiencing any of the following, this module is the likely solution for your 1998-1999 Express 3500 PCM issues:
- ✔ Check Engine Light is on with codes like P0601 (Internal Control Module Memory Check Sum Error) or P0606 (PCM Processor Fault).
- ✔ The engine cranks but refuses to start.
- ✔ Unexplained stalling or rough, erratic idling.
- ✔ Noticeable decrease in fuel economy.
- ✔ Harsh or incorrect automatic transmission shifting.
- ✔ Communication errors with your scan tool.
Your Straightforward Installation Guide
Installing your pre-programmed PCM is a job most DIYers can handle in under an hour with basic hand tools. This process avoids the need for specialized programming equipment.
- Safety First: Disconnect the negative terminal from your vehicle’s battery to prevent any electrical shorts.
- Locate the PCM: On the Express/Savana vans, the PCM is typically located in the engine compartment on the driver’s side, near the air filter housing.
- Disconnect and Remove: Carefully unplug the electrical connectors. There are usually retaining clips that need to be released. Once disconnected, unbolt the module from its mounting bracket.
- Install the New Module: Bolt the new PCM into the mounting bracket. Firmly and carefully reconnect the electrical harnesses, ensuring they click securely into place.
- Reconnect Power: Reattach the negative battery terminal.
- Perform Security Relearn (If Needed): In many cases, you will need to perform a simple security relearn procedure. Turn the key to the ‘ON’ position for 10-15 minutes, then ‘OFF’ for 10 seconds. Repeat this cycle three times. On the fourth try, the vehicle should start and run normally.
Verified Compatibility for Your GM Truck or Van
While this listing is for the 1998-1999 Express 3500 PCM, this versatile module, identified by service number 9355699, is the correct replacement for a vast range of popular GM vehicles from that era. It directly interchanges with part numbers 16266645, 16250279, 16258815, and 09366810. Always verify your original part has one of these numbers for guaranteed compatibility.
This module fits, but is not limited to, the following vehicles (with ID 9355699):
- ✔ 1998-1999 Chevrolet & GMC C/K 1500, 2500, 3500 Pickups (Gasoline)
- ✔ 1998-1999 Chevrolet Suburban & GMC Suburban (Gasoline)
- ✔ 1998-1999 Chevrolet Tahoe & GMC Yukon
- ✔ 1998-1999 Chevrolet Express & GMC Savana 1500, 2500, 3500 Vans (Gasoline)
- ✔ 1998 Chevrolet Astro & GMC Safari
- ✔ 1999 Cadillac Escalade
- ✔ 1998 Oldsmobile Bravada, S10 Blazer, S15 Jimmy, Isuzu Hombre (4.3L)
Frequently Asked Questions
Why do I need to provide my VIN?
Your VIN allows us to load the exact, correct GM software for your vehicle’s engine, transmission, and factory options. This ensures seamless integration and performance, just like the original module from the factory.
Is this part difficult to install?
No. With basic hand tools and our step-by-step guide, most people can complete the installation in under an hour. Because the module arrives pre-programmed, you avoid complex computer work.
Is this a new part?
This is a high-quality, used OEM (Original Equipment Manufacturer) part sourced from a salvaged vehicle. Each unit is thoroughly tested for functionality before being programmed and shipped, offering OEM reliability at a great value.
Will I need to do anything after installation?
You may need to perform a simple key-cycle security relearn procedure, which takes about 30 minutes and requires no special tools. Instructions are included above.
What if my original part has a different number on the sticker?
This PCM (9355699) is a direct replacement for several other part numbers, including 16266645, 16250279, 16258815, and 09366810. As long as your module has one of these numbers, this part will work perfectly.
What is the benefit of the newest GM updates?
Over the years, GM often released software updates to address common problems, improve transmission shifting, and enhance engine efficiency. By flashing your module with the latest software, you’re getting a part that can perform better than your original one did.