If you’re dealing with a 1998-1999 Chevy Express Van that’s giving you headaches—stalling at stoplights, refusing to start, or showing a persistent Check Engine Light—you’ve likely pinpointed the problem: a failing Powertrain Control Module (PCM). As a technician with over two decades of experience, I’ve seen firsthand how a faulty PCM can turn a reliable workhorse into a frustrating, unpredictable vehicle. This isn’t just a part; it’s the central computer managing everything from fuel mixture and spark timing to transmission shifting. When it fails, the symptoms can be all over the map.
This is your direct, no-hassle solution. We’re offering a dependable, used OEM PCM that has been thoroughly inspected and is ready for service. The best part? We handle the programming for you. Simply provide your vehicle’s VIN at checkout, and we will flash this module with the latest GM factory software specific to your Express Van. This critical step ensures all systems communicate correctly, restoring the performance and reliability you depend on. You get a part that’s ready to install right out of the box, saving you a costly trip to the dealership and the expense of specialized programming tools.
A Technician’s Notebook: The Intermittent No-Start Nightmare
A customer brought in a ’99 Savana 2500, a sister van to the Express, with a ghost of a problem. It would run perfectly for days, then refuse to start for an hour. No codes, no clear pattern. After checking fuel pressure, spark, and grounds until I was blue in the face, I noticed the security light was flashing randomly during the no-start events. This pointed me toward the PCM. These older modules are notorious for developing microscopic cracks in the solder joints from years of heat cycles. This creates intermittent connection breaks that don’t always set a hard fault code like a P0601. Swapping in a known-good, correctly programmed PCM solved the issue instantly. It’s a classic failure mode for these work vans.
Is Your Van Showing These Classic PCM Failure Signs?
- ✔ Persistent Check Engine Light with codes like P0601 (Internal Control Module Memory Check Sum Error) or other communication faults.
- ✔ Unexplained engine stalling, especially when coming to a stop or at idle.
- ✔ Complete no-start condition where the engine cranks but won’t fire up.
- ✔ Harsh or erratic automatic transmission shifting.
- ✔ Noticeable decrease in fuel economy.
- ✔ Failure to pass an emissions or smog test.
Your Straightforward PCM Installation Guide
Installing your replacement 1998-1999 Express 1500 PCM is a manageable job for a DIYer with basic tools. Follow these steps carefully to ensure a smooth process.
- Safety First: Always disconnect the negative terminal from your vehicle’s battery and secure it away from the post to prevent accidental reconnection.
- Locate the PCM: On most Express and Savana vans, the PCM is located in the engine compartment on the driver’s side, near the battery or firewall.
- Disconnect the Wiring Harnesses: Carefully unclip and disconnect all electrical connectors from the old PCM. These connectors have locking tabs that may need to be gently pried or squeezed to release. Inspect the connectors for any corrosion or damage.
- Remove the Old Module: Unbolt the PCM from its mounting bracket. Keep the mounting hardware, as you will need it for the new module.
- Install the New Module: Mount your replacement PCM onto the bracket and secure it with the original hardware. Reconnect all wiring harnesses firmly until they click into place.
- Reconnect the Battery: Reattach the negative battery terminal.
- Perform Security Relearn Procedure: This is a crucial final step. Turn the key to the ‘ON’ position (without starting the engine) and leave it for 10-15 minutes. The ‘Security’ light on the dash should turn off. Turn the key off for 10 seconds, then the vehicle should start and run normally. This syncs the new PCM with your vehicle’s anti-theft system.
Verified Fitment For These GM Trucks & Vans
This module is a direct replacement for units with service numbers 09355699, 16266645, 9355699, 16250279, 16258815, or 09366810. It is guaranteed to fit the following vehicles with matching options. Please verify your original part number or consult with us if you are unsure.
CHEVROLET 2500 PICKUP 98-99
CHEVROLET 3500 PICKUP 98-99
EXPRESS 1500 VAN 98-99
EXPRESS 2500 VAN 98-99 (gasoline)
EXPRESS 3500 VAN 98-99 (gasoline)
SUBURBAN 1500/2500 98-99 (gasoline)
TAHOE 98-99 (gasoline)
ASTRO 98
BLAZER S10 98
S10/S15/SONOMA 98 (4.3L)
GMC 1500 PICKUP 98-99 (5.0L, 5.7L)
GMC 2500 PICKUP 98-99
GMC 3500 PICKUP 98-99
SAVANA 1500 VAN 98-99
SAVANA 2500 VAN 98-99 (gasoline)
SAVANA 3500 VAN 98-99 (gasoline)
YUKON 98-99
SAFARI (GMC) 98
JIMMY S15 98
CADILLAC ESCALADE 99
OLDSMOBILE BRAVADA 98
ISUZU HOMBRE 98 (4.3L)
GMC ENVOY 98
Frequently Asked Questions
Do I need to do any programming myself?
No. We handle all the programming before we ship the part. Just provide your VIN during checkout, and it will arrive ready to install with the latest GM software for your specific vehicle.
What is the ‘Security Relearn Procedure’ and is it difficult?
It’s a simple, mandatory step to sync the new PCM with your vehicle’s anti-theft system. It requires no tools—you just need to follow the key-on/key-off sequence described in our installation guide. It typically takes about 10-15 minutes.
Is this a new part?
No, this is a quality-inspected, genuine OEM part sourced from a salvaged vehicle. This provides OEM reliability at a fraction of the cost of a new dealer part.
How 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.
What if my original part number isn’t on the list?
The list of compatible part numbers (09355699, 16266645, etc.) covers most applications for these vehicles. If your number is different, please contact us with your VIN and original part number. We can verify compatibility for you.