Restore Your Van’s Performance and Reliability
Is your 1998 or 1999 GMC Savana 1500 giving you headaches? Unexplained stalling, a persistent Check Engine Light, or a complete no-start condition can bring your work or travels to a grinding halt. As a technician with over two decades of experience, I’ve seen countless vehicles sidelined by a faulty Powertrain Control Module (PCM). This isn’t just a part; it’s the brain of your engine, and when it fails, it can create some of the most frustrating diagnostic mysteries.
This is a dependable, tested OEM PCM, service number 9355699, sourced from a salvaged vehicle. The real value here is our professional 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 get a component that’s ready to install right out of the box, eliminating the need for an expensive trip to the dealership for programming. This service ensures your engine and transmission operate exactly as the manufacturer intended, restoring lost power, fuel economy, and smooth operation.
From the Diagnostic Bay: The Intermittent Ghost
A customer brought in a ’99 Express van—a work vehicle that was losing him money every day it sat. It had an intermittent no-start condition. Two other shops had already replaced the fuel pump and the ignition switch to no avail. When it arrived at my bay, it started fine. The challenge with a failing PCM is that the symptoms can be erratic. I hooked up my scope and monitored the 5-volt reference signal from the PCM to the sensors. After letting it run for 30 minutes, I saw the voltage signal become erratic and then drop completely, stalling the engine. The PCM was failing internally when it got warm. A new, correctly programmed 1998-1999 Savana 1500 PCM solved the problem permanently. This simple swap saved the customer from throwing more parts at a problem he didn’t have.
Is Your Van Exhibiting These PCM Failure Signs?
A failing engine computer can manifest in numerous ways. If you’re experiencing any of the following, a faulty PCM could be the culprit:
- ✔ Check Engine Light is on with codes like P0601 (Internal Control Module Memory Check Sum Error) or other communication errors.
- ✔ The engine cranks but refuses to start.
- ✔ Intermittent stalling, especially after the engine warms up.
- ✔ Noticeable decrease in fuel economy.
- ✔ Harsh or erratic automatic transmission shifting.
- ✔ The scan tool cannot communicate with the PCM.
- ✔ Other modules on the vehicle are setting ‘loss of communication with PCM’ codes (U-codes).
Your Straightforward PCM Installation Guide
Replacing the PCM on these vans is a job most DIYers can handle with basic tools. Following these steps will ensure a smooth installation process for your 1998-1999 Savana 1500 PCM.
- Safety First: Disconnect the negative terminal from your vehicle’s battery and secure it away from the post to prevent accidental reconnection.
- Locate the PCM: On the Savana/Express vans, the PCM is typically located in the engine compartment, on the left-hand (driver’s) side, near the rear.
- Disconnect the Wiring: Carefully unplug the electrical connectors from the old PCM. These connectors have locking tabs that may need to be lifted or squeezed to release. Inspect the connectors for any corrosion or damage.
- Remove the Old Module: Unbolt the PCM from its mounting bracket. There are usually two or three bolts holding it in place.
- Install the New PCM: Mount your new, pre-programmed PCM onto the bracket and secure it with the bolts.
- Reconnect Everything: Firmly plug the wiring harnesses back into the new module until they click into place. Reconnect the negative battery terminal.
- Perform Security Relearn: After installation, you will likely need to perform a security relearn procedure (often called a CASE relearn or Passlock relearn). This procedure syncs the new PCM with your vehicle’s anti-theft system. It typically involves turning the key to the ‘ON’ position for 10-15 minutes, then ‘OFF’, and repeating two more times. Consult your vehicle’s service information for the exact procedure.
Verified Compatibility for Your GM Vehicle
This PCM, identified by service number 9355699, is a direct replacement for a wide range of GM trucks and vans. Please verify your vehicle is on this list and that your original module carries the ID ‘9355699’ or one of the interchangeable part numbers (09355699, 16266645, 16250279, 16258815, 09366810, 9366810). This module fits:
CHEVROLET EXPRESS / GMC SAVANA 1500/2500/3500 VAN (1998-1999)
CADILLAC ESCALADE (1999)
CHEVROLET TAHOE / GMC YUKON (1998-1999)
CHEVROLET / GMC SUBURBAN 1500/2500 (1998-1999)
CHEVROLET ASTRO / GMC SAFARI (1998)
OLDSMOBILE BRAVADA (1998)
GMC ENVOY (1998)
CHEVROLET S10 / GMC SONOMA (S15) (1998)
CHEVROLET BLAZER S10 / GMC JIMMY S15 (1998)
ISUZU HOMBRE (1998)
Do I need to do anything after I buy it?
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 program and ship the module without it. This ensures the PCM has the correct software for your specific vehicle configuration.
Is this a new part?
No, this is a high-quality, used OEM (Original Equipment Manufacturer) part that has been sourced from a salvaged vehicle. We inspect and test each unit before programming and shipping.
Will I need a mechanic to install this?
While the physical installation is straightforward for many DIYers, some vehicles require a security relearn procedure after installation. We provide general instructions, but you may need to consult a service manual for your specific vehicle’s procedure if you are unfamiliar with it.
What if my part number is slightly different?
This PCM with service number 9355699 is compatible with several other part numbers, including 16266645, 16250279, and more, as listed in the description. As long as your vehicle is listed and your original part number is in our compatibility list, this module will work once programmed to your VIN.