Restore Your GM Truck’s Brain and Get Back on the Road
If your trusty 1998-1999 Chevrolet Express 2500 Van is suddenly giving you headaches—stalling, running rough, refusing to start, or flashing a stubborn Check Engine Light—the problem often lies with the very heart of its electronic system: the Powertrain Control Module (PCM). As a technician with over two decades of experience under the hood, I’ve seen countless drivers replace expensive sensors and chase electrical gremlins, only to find the root cause was a failing PCM. This component is the central computer for your engine and transmission, and when it falters, your vehicle’s reliability disappears.
This isn’t just a replacement part; it’s a complete, ready-to-install solution. We take a reliable, tested OEM computer and professionally program it with the latest GM software updates, specifically tailored to your vehicle’s VIN. This critical step ensures your engine’s fuel maps, transmission shift points, and emissions controls are perfectly calibrated, restoring the performance and dependability you count on. By purchasing a pre-programmed module, you bypass the expensive trip to the dealership for flashing, saving you both time and money.
A Technician’s Notebook: Chasing an Intermittent Stall
I once had a 1999 Suburban in the shop that would stall without warning, but only after it was driven for 30 minutes. The owner had already replaced the fuel pump and ignition coil. No codes were stored. On a hunch, I monitored the 5-volt reference signal from the PCM to the sensors. Sure enough, after the engine bay heated up, the voltage would erratically drop, causing the stall. The culprit? A heat-sensitive capacitor failing inside the PCM. A simple swap with a quality, tested module like this one had the customer back on the road permanently. These intermittent issues are classic signs of a failing 1998-1999 Express 2500 PCM and its counterparts.
Is Your GM Truck or Van Showing These Symptoms?
A failing PCM can manifest in numerous ways. If you’re experiencing any of the following, this module is the likely solution after you’ve ruled out basic sensor or wiring faults:
- ✔ Check Engine Light is on with internal module codes like P0601 (Internal Control Module Memory Check Sum Error) or P0605 (Internal Control Module Read Only Memory (ROM) Error).
- ✔ The engine cranks but will not start.
- ✔ Unexplained drops in fuel economy.
- ✔ The transmission shifts harshly, late, or not at all.
- ✔ Intermittent stalling, especially when the engine is warm.
- ✔ Your diagnostic scan tool cannot communicate with the PCM.
- ✔ Failure to pass a state emissions inspection.
A Straightforward Guide to Your PCM Swap
For the confident DIYer or professional mechanic, installing this 1998-1999 Express 2500 PCM is a manageable job. Since we handle the programming, you won’t need any special scan tools for that step. Just follow these general instructions:
- Safety First: Always disconnect the negative terminal from your vehicle’s battery before starting any electrical work.
- Locate the PCM: On most GM trucks and vans of this era, the PCM is located in the engine compartment, typically on the driver’s side inner fender or near the battery.
- Disconnect the Connectors: Carefully unclip and remove the electrical harness connectors from the old PCM. Inspect them for any corrosion or damage.
- Remove the Old Unit: Unbolt the old PCM from its mounting bracket. Keep the hardware as you may need to reuse it.
- Install the New PCM: Mount your new, pre-programmed PCM onto the bracket and securely reconnect all electrical harnesses. Ensure they click into place.
- Reconnect the Battery: Reattach the negative battery terminal.
- Perform Security Relearn (If Needed): Some vehicles may require a simple security relearn procedure to recognize the new PCM. This typically involves turning the key to the ‘ON’ position for 10-15 minutes. Consult a service manual for your specific model’s procedure. A Crankshaft Variation (CASE) relearn may also be needed with a capable scan tool for optimal performance.
Verified Vehicle Compatibility
This module is a direct replacement for several part numbers and fits a wide range of GM vehicles. The most important factor is matching the Service ID number on your original computer’s sticker. This unit is compatible with modules identified as ID 9355699. Please verify your part number before ordering. This part is a confirmed fit for the following vehicles, among others:
- ✔ 1998-1999 Chevrolet & GMC C/K 1500, 2500, 3500 Pickups (Gasoline)
- ✔ 1998-1999 Chevrolet Express & GMC Savana 1500, 2500, 3500 Vans (Gasoline)
- ✔ 1998-1999 Chevrolet Suburban & GMC Yukon XL (Gasoline)
- ✔ 1998-1999 Chevrolet Tahoe & GMC Yukon (Gasoline)
- ✔ 1999 Cadillac Escalade
- ✔ 1998 Chevrolet Astro & GMC Safari
- ✔ 1998 Oldsmobile Bravada, Chevrolet Blazer/S10, GMC Jimmy/Sonoma, Isuzu Hombre (4.3L V6)
This module replaces part numbers: 09355699, 16266645, 16250279, 16258815, 09366810.
Frequently Asked Questions
Why do you need my VIN?
Your Vehicle Identification Number (VIN) is essential. We use it to load the exact, correct GM factory software for your vehicle’s specific engine, transmission, and options. This ensures perfect compatibility and performance, eliminating the need for a dealership visit.
Is this part difficult to install?
For someone with basic mechanical skills and tools, this is a very straightforward replacement. The main task is unbolting the old unit and plugging in the new one. Since the programming is already done, the most complex part of the job is handled before it even arrives at your door.
Will I need to do anything after installation?
In many cases, the vehicle will start and run immediately. However, some GM vehicles require a simple security relearn procedure to sync the new PCM with the anti-theft system. For best results, a Crankshaft Position System Variation (CASE) relearn using a compatible scan tool is recommended to prevent a P1336 trouble code, though the vehicle will still run without it.
How do I know if the PCM is actually the problem?
While the symptoms listed are strong indicators, it’s always best to perform a thorough diagnosis. Check for consistent power and ground at the PCM connector and rule out faulty sensors or wiring. If all other components check out and you have communication errors or internal module fault codes (like P0601), the PCM is the most likely culprit.
What does ‘used’ mean for this part?
This PCM is a genuine OEM part sourced from a salvaged vehicle. Each unit is inspected and tested to ensure it is fully functional before being programmed with fresh, updated software. This provides the reliability of an original factory part at a significant cost savings compared to a new unit.