Restore Peak Performance to Your GM Van or Truck
Is your 1998-1999 Chevrolet Express 1500 or other GM vehicle suffering from frustrating, hard-to-diagnose issues? A failing Powertrain Control Module (PCM) is often the hidden culprit behind problems like a persistent check engine light, erratic engine behavior, or poor fuel economy. As a technician with over two decades of experience, I’ve seen firsthand how a faulty PCM can disrupt the entire vehicle. This isn’t just a part; it’s the brain of your engine and transmission, and when it falters, everything else does too. We offer a dependable, cost-effective solution: a quality-tested, used OEM PCM, professionally flashed with the latest GM software updates specific to your vehicle’s VIN.
This process eliminates the guesswork and the expensive trip to the dealership. You’re not just buying a replacement part; you’re getting a plug-and-play solution that restores your vehicle’s factory-specified performance and reliability. By providing your VIN at checkout, you ensure this 1998-1999 Express 1500 PCM arrives ready for installation, getting you back on the road quickly and confidently.
Is Your Van Exhibiting These PCM Failure Signs?
A failing PCM can manifest in various ways. If you’re experiencing any of the following, your engine computer may be at fault. Look out for these common indicators:
- ✔ Unexplained Check Engine Light (CEL) illumination
- ✔ Diagnostic Trouble Codes (DTCs) like P0601, P0605, or P0606 pointing to internal module failure
- ✔ Engine stalling, stumbling, or refusing to start
- ✔ Noticeable decrease in fuel mileage
- ✔ Harsh or erratic automatic transmission shifting
- ✔ Failure to pass state emissions testing
- ✔ Communication errors with diagnostic scan tools
From the Diagnostic Bay: Solving the Phantom Stall
I remember a 1999 Express 2500 work van that came into my shop with a maddening intermittent stalling problem. The owner, a plumber, said it would die at stoplights without warning, but always restart. He’d already replaced the fuel pump and ignition coil pack with no success. After hooking up my scan tool, I noticed the data stream would freeze just before the engine quit—a classic sign of a processor issue. We confirmed the wiring and grounds were solid. The culprit was the PCM. Instead of a costly new unit and dealer programming, we sourced a tested, used module just like this one. We flashed it with his VIN, installed it, and performed a quick CASE relearn. The van ran perfectly, and the owner was back on the job the same afternoon. This is the exact, reliable fix we provide to you.
A Straightforward Guide to Installation
Installing your pre-programmed 1998-1999 Express 1500 PCM is a manageable job for a DIYer with basic tools. Follow these steps carefully for a smooth installation.
- Safety First: Always disconnect the negative terminal from your vehicle’s battery and secure it away from the post to prevent any accidental power surges.
- Locate the PCM: On most GM vans and trucks of this era, the PCM is located in the engine compartment, typically on the driver’s side fender well or near the battery.
- Disconnect the Connectors: Carefully unclip and remove the wiring harness connectors from the old PCM. These connectors have locking tabs that need to be released. Avoid pulling on the wires themselves.
- Remove the Old Module: Unbolt the old PCM from its mounting bracket. There are typically 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 harness connectors into the new module until they click into place. Reconnect the negative battery terminal.
- Security & Crankshaft Relearn: In many cases, you will need to perform a security relearn procedure (often involves cycling the key) and a Crankshaft Variation (CASE) relearn with a capable scan tool for optimal performance and to clear any related trouble codes.
Verified Compatibility For Your GM Vehicle
This PCM, identified by part numbers 16266645 and service ID 09355699 / 9355699, is a direct replacement for a wide range of GM vehicles. Please verify your original part number or consult the list below. This module is compatible with the following models:
- ✔ 1998-1999 Chevrolet & GMC C/K 1500/2500/3500 Pickups (Gasoline)
- ✔ 1998-1999 Chevrolet Suburban 1500/2500 (Gasoline)
- ✔ 1998-1999 Chevrolet Tahoe & GMC Yukon (Gasoline)
- ✔ 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)
- ✔ 1998 Chevrolet Blazer, GMC Jimmy, Oldsmobile Bravada, GMC Envoy (4.3L)
Important: This part is programmed using your VIN. A correct VIN is essential for proper function. Please double-check the VIN from your vehicle’s driver-side door jamb or dashboard plate.
Frequently Asked Questions About This PCM
Why do you need my VIN?
Your Vehicle Identification Number (VIN) allows us to flash the PCM with the exact software and calibrations your vehicle needs. This includes engine size, transmission type, and any specific options, ensuring it works perfectly right out of the box.
Is a used PCM reliable?
Absolutely. This is an Original Equipment (OE) module that has been sourced from a salvaged vehicle and thoroughly inspected. OE parts are often more durable than aftermarket alternatives. We then program it with the latest software, providing a reliable and affordable solution.
What is a ‘CASE Relearn’ and will I need to do one?
A Crankshaft Variation (CASE) relearn synchronizes the PCM with the crankshaft position sensor’s signal. While the vehicle will run without it, performing a CASE relearn with a compatible scan tool is highly recommended to ensure accurate misfire detection and optimal engine performance.
Is this part difficult to install myself?
The physical swap is straightforward for most DIYers. With the programming already done by us, you avoid the most complex step. You’ll need basic hand tools and may need a scan tool for the final relearn procedures for best results.
What if I have a different part number on my old computer?
This module replaces several part numbers, including 16266645, 09355699, 16250279, 16258815, and 09366810. As long as your vehicle is on the compatibility list, our VIN-based programming will ensure it functions correctly as a replacement.