Is Your GM Truck or Van Running Rough?
The Powertrain Control Module (PCM), often called the Engine Control Module (ECM), is the electronic brain of your 1998-1999 GM vehicle. It manages everything from fuel injection and ignition timing to transmission shifting and emissions control. When it starts to fail, it can cause a cascade of confusing and frustrating problems that can be difficult to diagnose. A faulty PCM can leave you stranded, fail an emissions test, or simply make your vehicle unreliable and inefficient.
From the Diagnostic Bay
I once had a ’99 Suburban in the shop that was driving the owner crazy. It would randomly stall at red lights, shift hard from first to second, and threw intermittent codes for the MAF sensor and an O2 sensor. The owner had already replaced both sensors, but the problems persisted. After hours of checking wiring and grounds, we hooked up a scope to the PCM’s 5-volt reference circuit. We saw the voltage erratically dropping out, a classic sign of an internal PCM failure. We installed a VIN-programmed module just like this one, performed the security relearn, and the truck ran like it just rolled off the assembly line. It’s a reminder that sometimes the root cause is the component controlling everything else.
Symptoms of a Failing Powertrain Control Module
If you’re experiencing any of the following issues, a failing PCM could be the culprit. Don’t let a faulty computer keep your reliable GM truck or van off the road. This replacement 1998-1999 Express 3500 PCM is the definitive solution to restore your vehicle’s performance and dependability.
- ✔ Check Engine Light is on with various, often unrelated, trouble codes (DTCs).
- ✔ Vehicle refuses to start or stalls intermittently.
- ✔ Noticeable decrease in fuel economy.
- ✔ Harsh or erratic automatic transmission shifting.
- ✔ Engine misfires, stumbles, or runs poorly.
- ✔ Communication errors with diagnostic scan tools.
- ✔ Failure to pass state emissions inspections.
The Right Part, Programmed for Your Vehicle
This isn’t just a used part pulled from a shelf. This is a genuine, used OEM Powertrain Control Module that undergoes a crucial programming process before it ships. When you place your order, you provide us with your vehicle’s 17-digit Vehicle Identification Number (VIN). Our technicians then use that VIN to flash the module with the latest, most up-to-date software calibration directly from General Motors. This ensures the PCM is a perfect electronic match for your vehicle’s specific engine, transmission, and options.
This service eliminates the need for expensive trips to the dealership for programming. The module arrives ready for installation. While the programming is handled, you will likely need to perform a simple security relearn procedure after installation, which pairs the new PCM to your vehicle’s anti-theft system. This procedure can typically be done in your driveway without any special tools.
Guaranteed Compatibility
This module, identified by part number 09355699, is a direct replacement for several other service numbers, including 16266645, 9355699, 16250279, 16258815, 09366810, and 9366810. It fits a massive range of popular 1998-1999 GM trucks, vans, and SUVs, such as the Chevrolet Express, GMC Savana, Tahoe, Yukon, Suburban, C/K Pickups, Astro, Safari, and Cadillac Escalade. Please verify the part number on your original module to ensure a perfect match.
Frequently Asked Questions
Why is VIN programming necessary for this Express 3500 PCM?
Programming the PCM with your VIN ensures it has the correct software for your vehicle’s specific engine, transmission, emissions equipment, and other options. An incorrectly programmed module can cause poor performance, check engine lights, or even prevent the vehicle from starting.
Is this a new part?
No, this is a high-quality, tested, used OEM (Original Equipment Manufacturer) part sourced from a salvaged vehicle. This ensures OEM-level fit and function without the high cost of a new module.
What do I need to do after I install the computer?
After installation, you will need to perform a security relearn procedure, also known as a Passlock or Passkey relearn. This procedure pairs the new PCM to your vehicle’s anti-theft system and allows the engine to start. Instructions for this are widely available online and typically involve a sequence of turning the key on and off.
Where do I find my vehicle’s VIN?
Your 17-digit 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.
Will this fix my vehicle’s problem?
This PCM will resolve issues directly caused by a faulty original module. However, it’s crucial to ensure your vehicle has been properly diagnosed. This part will not fix problems related to bad sensors, faulty wiring, or other mechanical issues.