Restore Peak Performance to Your GM Truck or Van
Is your late-90s GM vehicle suffering from perplexing issues like a persistent check engine light, rough idling, stalling, or erratic shifting? These are classic symptoms of a failing Powertrain Control Module (PCM), the central computer that governs your engine and transmission. This genuine used OEM PCM, service number 9355699, is the reliable and affordable solution to get your truck or van running smoothly again. Unlike a generic unit from a local parts store, this module is specifically programmed to your vehicle’s unique Vehicle Identification Number (VIN), ensuring seamless integration and correct operation of all systems right out of the box.
From the Diagnostic Bay
I once had a 1999 Chevy Suburban in the shop that was driving the owner crazy. He’d replaced the fuel pump, spark plugs, and multiple sensors trying to chase down an intermittent stalling problem that never set a consistent code. After hooking up the scan tool and watching the live data, I noticed the injector pulse width was fluctuating wildly at idle. The sensors were sending good signals, but the computer wasn’t commanding the injectors correctly. We swapped in a VIN-programmed PCM like this one, and the truck immediately idled perfectly. It wasn’t a bad sensor or a fuel issue; the original computer’s driver circuit was simply worn out. This part saved him from throwing more money at parts he didn’t need.
Diagnosing a Faulty 1998 Envoy PCM
The PCM is the brain of your vehicle’s powertrain. When it starts to fail, it can cause a wide range of confusing symptoms that often mimic other component failures. By understanding these signs, you can avoid replacing unnecessary parts and target the root cause of the problem. This module is the correct fix for a vehicle experiencing these issues due to a faulty computer.
Common Symptoms of PCM Failure
- âś” Check Engine Light: Your check engine light is on, often with communication error codes (U-codes) or codes for multiple, unrelated sensors.
- âś” No-Start or Hard Starting: The engine cranks but refuses to start, or takes an excessive amount of time to fire up, either hot or cold.
- âś” Poor Engine Performance: You may experience a noticeable loss of power, hesitation during acceleration, and a significant drop in fuel economy.
- âś” Rough or Stalling Idle: The engine idles erratically or stalls unexpectedly, especially when coming to a stop.
- âś” Erratic Transmission Shifting: The PCM also controls transmission functions, so a failure can lead to harsh shifts, delayed engagement, or getting stuck in one gear.
- âś” Failed Emissions Test: A malfunctioning PCM can prevent the emissions system monitors from running, leading to an automatic failure at the inspection station.
Why VIN Programming is Essential
Modern vehicles are complex, and the PCM needs to know everything about your specific truck—from the engine and transmission type to the axle ratio and tire size. Our process ensures this is a true plug-and-play solution. When you provide your VIN, we flash this module with the latest factory software from GM, tailored precisely to your vehicle’s build. This critical step eliminates compatibility conflicts and ensures your engine, transmission, anti-lock brakes, and other systems all communicate correctly, restoring original factory performance and reliability.
Frequently Asked Questions
What information do I need to provide for programming?
After you complete your purchase, you will need to send us your vehicle’s 17-digit VIN (Vehicle Identification Number). We cannot ship the part until we have this information to program the module correctly.
Is this a new part?
No, this is a genuine, used OEM part sourced from a salvaged vehicle. Each unit is thoroughly inspected and tested to ensure it is fully functional before being programmed and shipped.
Will I need to do any additional programming myself?
The core engine and transmission programming is done for you. However, on many of these GM vehicles, you may need to perform a simple Security Relearn Procedure (also known as a CASE relearn or Passlock relearn) after installation. This procedure can typically be done without special tools and involves a sequence of key turns. Instructions are widely available online for your specific model.
How do I know if this part number is correct for my vehicle?
This PCM with service number 9355699 is a direct replacement for several other part numbers, including 16266645, 16250279, and 09366810. Please check the comprehensive fitment list on this page and verify the part number on your original module to ensure compatibility.
Will this fix my check engine light?
If the check engine light and associated codes are being caused by a faulty PCM, then yes, this part will resolve the issue. However, it’s crucial to ensure your vehicle’s underlying issues (like a bad sensor or wiring short) have been fixed first, as a new PCM will not fix a separate mechanical or electrical problem.