Restore Your Van’s Performance and Reliability
Is your 1998 or 1999 Chevrolet Express 3500 Van running rough, stalling unexpectedly, or refusing to start? A failing Powertrain Control Module (PCM) is often the culprit behind these frustrating and costly issues. As the brain of your vehicle, the PCM controls everything from fuel mixture and ignition timing to transmission shifting. When it fails, your workhorse van can quickly become unreliable. This is a dependable, cost-effective solution to get you back on the road with confidence.
This isn’t just a replacement part; it’s a complete, ready-to-install solution. Each module is a genuine, used OEM unit sourced from a salvaged vehicle and is meticulously programmed with the latest GM software updates specific to your van’s Vehicle Identification Number (VIN). This critical step ensures perfect communication between the module and your vehicle’s systems, eliminating the need for an expensive trip to the dealership for programming. For the professional mechanic or the savvy DIYer, this means less downtime and a more efficient repair. This is the smart way to fix your 1998-1999 Express 3500 PCM and restore its original performance.
A Technician’s Notebook: The Intermittent Stall Case
I remember a customer bringing in his ’99 Savana 3500—a sister vehicle to the Express—with a ghost of a problem. It would run perfectly for days, then suddenly stall at a red light and refuse to restart for 20 minutes. No consistent check engine light, just random chaos. We checked fuel pressure, spark, and sensors, and everything looked fine. After hours of diagnostics, I noticed the scanner would lose communication with the PCM right before it stalled. That’s the classic sign. Heat soak was causing an internal solder joint in the original PCM to fail intermittently. We swapped in a VIN-programmed module just like this one, and the problem was solved instantly. These failures are common in this generation of GM trucks and vans, and a quality replacement is the only permanent fix.
Is Your Van Exhibiting These Classic PCM Failure Signs?
A faulty engine computer can cause a wide range of symptoms. If you’re experiencing any of the following, a failing PCM is a likely cause. Look out for:
- ✔ 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 will not start.
- ✔ Unexplained stalling or rough idling, especially after the engine warms up.
- ✔ A significant drop in fuel economy.
- ✔ Harsh or erratic automatic transmission shifting.
- ✔ Communication errors with your scan tool (U-codes).
- ✔ Apparent failure of multiple sensors at once.
Your Straightforward Installation Guide
Replacing the 1998-1999 Express 3500 PCM is a job most DIYers can handle with basic tools. Our pre-programmed module makes it even easier. Follow these steps for a successful installation:
- Safety First: Disconnect the negative terminal from your vehicle’s battery to prevent any electrical shorts.
- Locate the PCM: On most Express and Savana vans, the PCM is located in the engine compartment on the driver’s side, near the air filter housing.
- Disconnect the Connectors: Carefully unplug the electrical harness connectors from the old PCM. There are typically release tabs that need to be pressed or lifted.
- Remove the Old Module: Unbolt the old PCM from its mounting bracket. Keep the hardware, as you may need it for the new module.
- Install the New PCM: Mount your new, VIN-programmed PCM onto the bracket and securely plug in the electrical connectors. You should hear a click as they lock into place.
- Reconnect the Battery: Re-attach the negative battery terminal.
- Perform Security Relearn (If Needed): Some GM vehicles of this era require a simple security relearn procedure. This usually involves turning the key to the ‘ON’ position for 10-15 minutes, then off, and repeating two more times before starting the engine. This allows the new PCM to sync with your vehicle’s anti-theft system.
Verified Fitment for Your GM Truck or Van
This module, identified by part number 16250279 or service ID 9355699, is a direct replacement for a wide array of GM trucks, vans, and SUVs from the late 90s. Please confirm your vehicle is on this list and provide your VIN upon purchase for correct programming. This part fits:
- Chevrolet Express / GMC Savana Vans (1500, 2500, 3500): 1998-1999 (Gasoline engines)
- Chevrolet / GMC Pickups (1500, 2500, 3500): 1998-1999 (Gasoline engines, including 5.0L & 5.7L)
- Chevrolet Tahoe / GMC Yukon: 1998-1999 (Gasoline engines)
- Chevrolet Suburban (1500, 2500): 1998-1999 (Gasoline engines)
- Cadillac Escalade: 1999
- Chevrolet Astro / GMC Safari: 1998
- Chevrolet S10 / GMC Sonoma / Isuzu Hombre: 1998 (4.3L V6)
- Oldsmobile Bravada / Chevrolet Blazer / GMC Jimmy / GMC Envoy: 1998 (4.3L V6)
This module replaces part numbers: 09355699, 16266645, 9355699, 16250279, 16258815, 09366810, 9366810.
Frequently Asked Questions About Your New PCM
Frequently Asked Questions
What information do you need to program my PCM?
After you complete your purchase, we will need your vehicle’s 17-digit Vehicle Identification Number (VIN). This ensures we load the exact, correct GM software for your van’s specific options and configuration.
Is this a used part?
Yes, this is a fully tested, genuine OEM computer that was recovered from a salvaged vehicle. We inspect and program it to ensure it functions correctly before shipping it to you.
Will I need to do anything after I install it?
Because this unit comes programmed to your VIN, it’s a direct installation. In some cases, you may need to perform a simple security relearn procedure, which takes about 30 minutes and requires no special tools. We can provide instructions for this process.
What is the difference between a PCM and an ECM?
ECM stands for Engine Control Module, while PCM stands for Powertrain Control Module. In many modern vehicles, including your 1998-1999 Express 3500, the PCM controls both the engine and the transmission, so the terms are often used interchangeably. This unit is a PCM.
Will this fix my check engine light?
If the check engine light is caused by an internal failure of your existing PCM (like code P0601), then yes, this part is the correct fix. It’s always best to have the codes read by a professional or with a code reader to properly diagnose the issue before ordering parts.