Restore Your Van’s Core Performance and Reliability
Is your 1998-1999 Chevrolet Express 3500 Van suddenly stalling, running rough, or refusing to start? As a technician with over two decades of experience, I’ve seen these symptoms countless times. Often, the culprit isn’t a mechanical part, but the vehicle’s central computer—the Powertrain Control Module (PCM). This critical component is the brain of your engine, managing everything from fuel injection and spark timing to transmission shifting. When it fails, it can cause a cascade of frustrating and hard-to-diagnose problems.
This isn’t just a replacement part; it’s a complete solution. We offer a reliable, tested, and used OEM PCM that is professionally programmed to your van’s specific Vehicle Identification Number (VIN). This means it arrives at your door with the latest GM software updates already installed, ready for a straightforward installation. You get to skip the expensive trip to the dealership and the hassle of coordinating a tow just for programming. This is the direct, cost-effective fix to get your workhorse back on the job.
A Technician’s Notebook: The Intermittent Stall Case
I once had a 1999 Savana 3500 come into my bay with an issue that was driving the owner crazy. The van, used for a delivery business, would run perfectly for days and then suddenly stall at a stoplight. No check engine light, no consistent codes. After checking fuel pressure, spark, and sensors, everything seemed fine. On a hunch, I tapped the PCM with a screwdriver handle while the engine was idling, and it immediately stumbled. The internal connections were failing intermittently from years of heat and vibration. A replacement, pre-programmed PCM like this one had the van back in reliable service the same afternoon. It’s a classic failure mode for these hard-working vehicles.
Is Your Van Exhibiting These PCM Failure Symptoms?
A faulty engine computer can manifest in many ways. If you’re experiencing any of the following, a failing 1998-1999 Express 3500 PCM could be the root cause:
- ✔ Check Engine Light is on with codes like P0601 (Internal Memory Error) or P0606 (PCM Processor Fault).
- ✔ The engine cranks but refuses to start.
- ✔ Unexplained stalling or rough idling, especially when warm.
- ✔ A noticeable drop in fuel economy.
- ✔ Harsh or erratic automatic transmission shifting.
- ✔ Communication errors with your scan tool.
A Straightforward Guide to Installation
Installing your programmed PCM is a manageable job for a DIYer with basic tools. Following these steps will ensure a smooth process.
- Safety First: Always disconnect the negative terminal from your vehicle’s battery and wait at least 15 minutes for the system capacitors to discharge.
- Locate the PCM: On the Express/Savana vans, the PCM is typically located in the engine compartment on the driver’s side, near the firewall or inner fender.
- Disconnect Connectors: Carefully unclip the wiring harness connectors from the old PCM. These connectors have locking tabs; do not force them. Inspect the pins for any corrosion or damage.
- Remove the Old Module: Unbolt the old PCM from its mounting bracket and remove it from the vehicle.
- Install the New PCM: Mount your new, pre-programmed PCM onto the bracket and securely reconnect the wiring harnesses. Ensure they click into place.
- Reconnect Battery: Reattach the negative battery terminal.
- Perform Security Relearn: You will likely need to perform a GM Security Relearn procedure. This typically involves turning the key to the ‘ON’ position for 10-15 minutes, then ‘OFF’ for 10 seconds, and repeating this cycle three times. This allows the vehicle’s anti-theft system to recognize the new PCM.
Guaranteed Fitment for Your GM Truck or Van
This module, identified by service number 16266645 or ID 9355699, is a direct replacement for a wide range of GM vehicles. Please verify your part number before ordering. This part is compatible with the following models:
- ✔ 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)
- ✔ 1999 Cadillac Escalade
- ✔ 1998 Chevrolet Astro & GMC Safari
- ✔ 1998 Chevrolet S10, GMC Sonoma, Isuzu Hombre (4.3L V6)
- ✔ 1998 Chevrolet S10 Blazer & GMC S15 Jimmy
- ✔ 1998 Oldsmobile Bravada & GMC Envoy
Frequently Asked Questions
Do I need to do any programming myself?
No. This PCM comes fully programmed to your vehicle’s VIN with the latest GM software. All you need to do is provide us with your VIN at checkout, and we handle the rest before shipping.
What is a ‘Security Relearn’ and is it difficult?
The Security Relearn (or anti-theft relearn) is a simple procedure that syncs the new PCM to your vehicle’s security system. It doesn’t require any special tools and typically involves a series of key cycles. We can provide instructions for this easy, but necessary, step.
Is this a new part?
No, this is a thoroughly tested, genuine OEM part sourced from a salvaged vehicle. This provides OEM reliability and function at a fraction of the cost of a new-from-dealer part.
Will this fix my transmission shifting problems?
In many cases, yes. The PCM also controls transmission functions, including shift points and line pressure. If your shifting issues are caused by a faulty computer, this part will resolve them. However, it will not fix mechanical issues within the transmission itself.
Where do I find my vehicle’s VIN?
Your 17-digit Vehicle Identification Number (VIN) can be found on your vehicle’s registration, insurance card, or on a metal plate on the driver’s side of the dashboard, visible through the windshield.