Is Your GM Truck or Van Running Rough?
If you’re dealing with a no-start condition, erratic engine behavior, or a check engine light that just won’t go away on your 1998-1999 GM vehicle, a failing Powertrain Control Module (PCM) is often the culprit. In my 20+ years in the shop, I’ve seen countless GMT400 trucks and Express/Savana vans with these exact issues. You replace sensors, check wiring, and still, the problem persists. The PCM is the brain of your engine, and when it fails, it can cause a cascade of frustrating and hard-to-diagnose symptoms.
The Direct Solution: A VIN-Programmed PCM
This isn’t just a replacement part; it’s a complete, ready-to-install solution. This is a reliable, used OEM PCM that we program specifically to your vehicle’s Vehicle Identification Number (VIN) before it ships. This critical step ensures that the module communicates perfectly with your engine, transmission, and all related systems. We load the latest GM software updates, which can often resolve underlying drivability issues that were present even from the factory. Forget expensive dealer visits and towing fees—this module is designed for a straightforward installation right in your own driveway.
Expert Pro Tip: Check Your Grounds Before You Swap!
Before you condemn your old PCM, take 10 minutes to check the main ground connections. On these late 90s GM trucks and vans, the primary ground strap from the engine block to the frame is notorious for corrosion. A poor ground can cause voltage drops and create bizarre electrical issues that perfectly mimic a bad computer. A quick cleaning with a wire brush can sometimes solve the problem entirely. If the grounds are clean and tight, you can proceed with the PCM replacement with confidence.
Common Symptoms of a Failing GM PCM:
- ✔ Persistent Check Engine Light (CEL) with various codes
- ✔ Engine cranks but will not start
- ✔ Harsh or erratic automatic transmission shifting
- ✔ Poor fuel economy and loss of power
- ✔ Stalling or intermittent misfires
- ✔ Communication errors with scan tools
Easy Installation for Your 1998-1999 Express 3500 PCM
Getting your truck back on the road is simple. No special tools or dealer programming required.
- Safety First: Disconnect the negative terminal from your vehicle’s battery.
- Locate the PCM: On most of these vehicles, it’s found in the engine compartment, typically on the driver’s side fender or near the battery.
- Disconnect Connectors: Carefully unclip the wiring harness connectors from the old PCM. Inspect the pins for any corrosion or damage.
- Swap the Module: Unbolt the old PCM and secure the new, pre-programmed module in its place.
- Reconnect and Test: Plug the wiring harnesses firmly into the new PCM, reconnect your battery terminal, and start the vehicle. Your issues should be resolved.
Guaranteed Compatibility
This used PCM, part number 16266645, is a direct replacement for several service numbers. Please verify your part number or match your vehicle in the list below. After purchase, simply provide us with your VIN so we can ensure a perfect software match.
Replaces Part Numbers: 09355699, 16266645, 9355699, 16250279, 16258815, 09366810, 9366810
This module fits a wide range of 1998-1999 GM models, including:
Astro, Blazer S10, Bravada, Chevrolet/GMC Pickups (1500, 2500, 3500), Escalade, Envoy, Express/Savana Vans (1500, 2500, 3500), Isuzu Hombre, Jimmy S15, S10/S15/Sonoma, Suburban, Tahoe, and Yukon. Please refer to the detailed fitment list in the original description to confirm your specific application and options.