Is Your GM Truck or Van Running Rough?
If you’re dealing with a persistent check engine light, stalling, poor fuel economy, or a vehicle that just won’t start, the problem might be deeper than a simple sensor. The Powertrain Control Module (PCM), often called the Engine Control Module (ECM), is the central computer of your vehicle. It manages everything from fuel injection and ignition timing to transmission shifting. When it fails, it can cause a wide range of frustrating and difficult-to-diagnose issues. Don’t let a faulty computer keep your reliable GM vehicle off the road. This fully programmed PCM is the definitive solution to restore your engine’s performance and reliability.
Common Symptoms of a Failing PCM
A failing engine computer can mimic many other problems. If you’re experiencing any of the following, it’s a strong indicator that your PCM may need replacement:
- ✔ Check Engine Light: Your check engine light is on, and you may have codes related to PCM internal failure, communication errors (U-codes), or multiple unrelated sensor faults.
- ✔ Engine Stalling or Misfiring: The engine may stall for no reason, run rough, or misfire, especially after warming up.
- ✔ No-Start Condition: The engine cranks but refuses to start, often due to the PCM not firing the fuel injectors or ignition coils.
- ✔ Poor Performance & Fuel Economy: A noticeable drop in power, acceleration, and a significant increase in fuel consumption.
- ✔ Erratic Transmission Shifting: The PCM also controls transmission functions, and a failure can lead to harsh shifts, getting stuck in gear, or incorrect shift points.
- ✔ Failed Emissions Test: An inability to pass smog or emissions testing is a common sign of a malfunctioning engine computer.
From the Diagnostic Bay
We had a 1998 Chevy C1500 in the shop that was driving the owner crazy. It had a random, intermittent misfire that no one could pinpoint. The owner had already replaced the spark plugs, wires, cap, rotor, and even the fuel injectors. The codes were inconsistent. After hooking up our diagnostic scanner and monitoring live data, we noticed the injector pulse width for cylinder 3 would occasionally drop out. We checked the wiring from the PCM to the injector and found it was perfect. The problem was internal—the injector driver circuit inside the original PCM was failing. We installed a correctly programmed GM PCM 09355699, performed a quick security relearn, and the truck ran like it just rolled off the assembly line. It’s a classic case where chasing symptoms costs more than fixing the root cause.
The Smart Solution: A VIN-Programmed PCM
Why choose our PCM? Because this isn’t just a part in a box. It’s a complete, ready-to-install solution. We take a tested, genuine used GM module and flash it with the latest official GM software calibration for your specific vehicle. This is done using the Vehicle Identification Number (VIN) you provide at checkout. This critical step ensures that the computer is a perfect match for your vehicle’s engine, transmission, and factory options.
By programming the module before shipping, we save you a trip to the dealership and the high costs associated with their programming services. This makes the replacement process faster, easier, and much more affordable. This is a direct-fit replacement for multiple part numbers, including 09355699, 16266645, 16250279, 16258815, and 09366810.
Simple Installation Process
Replacing the PCM is a straightforward job for a DIY mechanic or any professional technician. While specific locations vary slightly, it’s typically found in the engine bay.
- Disconnect the Battery: Always disconnect the negative battery terminal before working on any electronic components.
- Locate and Remove the Old PCM: Unplug the wiring harness connectors and unbolt the module from its bracket.
- Install the New PCM: Bolt the new module in place and securely reconnect the wiring harnesses. Ensure the clips are fully seated.
- Reconnect the Battery: Reattach the negative battery terminal.
- Perform Security Relearn (if necessary): In most cases, the vehicle will start and run immediately. Some GM vehicles may require a simple security relearn procedure (often called a CASE relearn) to sync with the vehicle’s anti-theft system, which can be done with a capable scan tool or by a local shop.
By purchasing this GM PCM 09355699, you are getting a cost-effective, reliable part that is guaranteed to be compatible with your vehicle’s system, restoring its original performance and functionality.
Frequently Asked Questions
Why do you need my vehicle’s VIN?
Your VIN is essential for us to load the exact, correct GM factory software for your vehicle’s specific engine, transmission, and options. This ensures perfect compatibility and function right out of the box, eliminating the need for expensive dealership programming.
Is this part difficult to install?
Installation is straightforward for anyone with basic mechanical skills. It involves disconnecting the battery, unplugging the old module, and plugging in the new one. No special tools are typically required for the physical replacement.
Will this fix my check engine light?
If the check engine light is caused by a faulty PCM, then yes, this part will resolve the issue. It’s crucial to have your vehicle properly diagnosed to confirm the PCM is the source of the problem before ordering.
Is this a new computer?
This is a high-quality, tested, and fully functional used computer sourced from a salvaged vehicle. Each unit is inspected and then programmed with fresh, updated software to ensure reliability and performance.
Do I need to send my old PCM back?
No core charge or return is required for this part. You can keep or dispose of your old module at your convenience.