Restore Peak Performance to Your GM Truck or Van
Is your trusty Chevrolet Express or GMC Savana suddenly unreliable? If you’re dealing with frustrating issues like stalling, a persistent check engine light, or a no-start condition, a failing Powertrain Control Module (PCM) is a very common culprit on these workhorse vehicles. As a technician with over two decades of experience under the hood, I’ve seen firsthand how a faulty PCM can create a cascade of baffling problems. This isn’t just a part; it’s the solution to getting your vehicle’s brain back in working order and restoring the dependability you rely on.
Case Study: A Tricky Diagnosis
I remember a 1999 Suburban that came into my bay with an intermittent no-start and random stalling that had stumped two other shops. The owner was a contractor who was losing money every day the truck was down. There were no consistent trouble codes, just a history of random communication errors. After verifying the wiring and power/ground circuits to the PCM, we connected a scope. We found that the 5-volt reference signal from the PCM would periodically drop out, causing the engine to die. It was a classic internal PCM failure. We replaced it with a VIN-programmed module just like this one, and the truck has been running solid for him ever since. This simple swap saved him from replacing countless sensors and chasing phantom electrical gremlins.
Is Your GM Truck or Van Showing These Signs?
A failing PCM can manifest in many ways. If you’re experiencing any of the following, it’s a strong indicator that your engine computer may need replacement:
- ✔ Unexplained Check Engine Light (CEL) with codes like P0601 (Internal Control Module Memory Check Sum Error) or P0606 (PCM Processor Fault).
- ✔ Engine stalling, sputtering, or cutting out while driving.
- ✔ Complete no-start condition where the engine cranks but won’t fire up.
- ✔ Harsh or erratic automatic transmission shifting.
- ✔ A noticeable drop in fuel economy.
- ✔ Communication issues with diagnostic scan tools.
The Smart Solution: VIN-Programmed and Ready for Installation
Don’t waste time and money at a dealership. This is a reliable, tested, used OEM 1998-1999 Express 2500 PCM that offers a dependable and affordable fix. The real value is in our professional programming service. Before we ship it, our technicians will flash the module with the latest official GM software updates, specifically matched to your vehicle’s VIN. This critical step ensures all operating parameters for the engine, transmission, and emissions systems are correct for your exact configuration. It arrives at your door ready for a straightforward installation, eliminating the need for expensive specialty tools or a trip to the dealer for programming.
A Straightforward Guide to Installation
Replacing the PCM on these GM vehicles is a job most DIYers can handle in their own driveway. Follow these general steps to get your vehicle back on the road.
- Safety First: Always disconnect the negative terminal from your vehicle’s battery and secure it away from the post to prevent any accidental reconnection.
- Locate the PCM: On most of these trucks and vans (like the Express, Savana, Tahoe, and pickups), the PCM is located in the engine compartment, typically on the driver’s side near the firewall or fender.
- Disconnect the Connectors: Carefully unclip and remove the electrical harness connectors from the old module. These connectors have locking tabs that need to be released before they can be pulled off. Avoid forcing them.
- Remove the Old Module: Unbolt the PCM from its mounting bracket and remove it from the vehicle.
- Install the New Module: Mount your new, pre-programmed PCM into the bracket and securely re-attach the electrical connectors, ensuring they click into place.
- Reconnect the Battery: Re-attach the negative battery terminal.
- Perform Security Relearn (if necessary): Some GM vehicles with Passlock or VATS security systems may require a simple key-cycle relearn procedure to sync the new PCM. This typically involves turning the key to the ‘ON’ position for 10-15 minutes, then off, and repeating two more times. Your vehicle’s service manual will have the specific steps if needed.
Verified Vehicle Compatibility
This module, identified by service number 9355699, is a direct replacement for a wide range of GM vehicles. It is also interchangeable with part numbers 16266645, 16250279, 16258815, and 9366810. Please verify your part number or match your vehicle from the list below. This part fits:
- ✔ Cadillac Escalade: 1999
- ✔ Chevrolet Astro / GMC Safari: 1998
- ✔ Chevrolet Blazer / GMC Jimmy S15 / Oldsmobile Bravada: 1998
- ✔ Chevrolet/GMC C/K 1500, 2500, 3500 Pickups: 1998-1999
- ✔ Chevrolet/GMC Suburban 1500, 2500: 1998-1999
- ✔ Chevrolet/GMC Tahoe/Yukon: 1998-1999
- ✔ Chevrolet Express / GMC Savana 1500, 2500, 3500 Vans: 1998-1999
- ✔ GMC Envoy: 1998
- ✔ Isuzu Hombre: 1998
- ✔ Chevrolet S10 / GMC Sonoma: 1998
This is a cost-effective and reliable way to solve complex engine management problems. By purchasing this programmed 1998-1999 Express 2500 PCM, you’re getting a part that is ready to restore your vehicle’s original performance and efficiency.
Frequently Asked Questions
Why do you need my Vehicle Identification Number (VIN)?
Your VIN is essential. It allows us to load the exact, correct GM factory software for your vehicle’s specific engine, transmission, and options. This ensures seamless integration and proper function without any additional programming required on your end.
Is a used computer module a reliable part?
Absolutely. These OEM modules were built to be very durable. Failures are typically due to age or electrical shorts, not widespread defects. Each unit we sell is sourced from a salvaged vehicle and inspected before being programmed and shipped, offering a dependable and affordable alternative to a new part.
Will I need to have a dealer do anything after I install it?
No. Because we program the module to your VIN before shipping, you can skip the expensive trip to the dealership. In some cases, a simple ‘security relearn’ procedure may be needed, which you can do yourself in about 30 minutes with just the ignition key.
My original part number is 16266645. Will this part 9355699 work?
Yes, it will. Part number 9355699 is the base service number for a family of modules. It is a direct, interchangeable replacement for part numbers 16266645, 16250279, 16258815, and 9366810, among others listed in our fitment data.