Is Your GM Vehicle Running Rough? It Could Be The PCM.
If you’re experiencing perplexing engine issues with your 1999-2000 Pontiac Bonneville, Chevrolet Impala, or other compatible GM vehicle, the root cause might be the very brain of your engine’s operation: the Powertrain Control Module (PCM). This critical component, also known as an ECM, is responsible for managing everything from fuel injection and ignition timing to transmission shift points and emissions controls. When it begins to fail, it can create a cascade of problems that are often misdiagnosed, leading to wasted time and money on unnecessary repairs.
A faulty PCM can manifest in numerous ways, from a simple check engine light to a frustrating no-start condition. Because it interfaces with dozens of sensors and controls multiple systems, pinpointing it as the culprit requires careful diagnosis. This genuine, used OEM module, part number 09361735, is the reliable and cost-effective solution to restore your vehicle’s performance and get you back on the road with confidence.
From the Diagnostic Bay
We once had a 1999 Pontiac Grand Prix GTP in the shop with an intermittent no-start and stalling issue that was driving the owner crazy. They had already replaced the fuel pump and filter, but the problem persisted. All the basic checks for fuel and spark were inconclusive because the issue was so sporadic. After hooking up a scope, we noticed the control signal to the fuel pump relay was dropping out randomly. Instead of a bad relay or wiring, we traced the circuit back to the PCM. The driver circuit inside the module was failing under certain temperature conditions. We installed a correctly programmed replacement PCM, and the car ran perfectly. It’s a classic example of how a failing PCM can mimic other, more common component failures.
Symptoms of a Failing 1999-2000 Bonneville PCM
- ✔ Check Engine Light (CEL) is on with various communication or sensor-related codes.
- ✔ Engine stalling, stumbling, or misfiring for no apparent reason.
- ✔ Harsh or erratic automatic transmission shifting.
- ✔ Complete no-start condition where the engine cranks but will not fire.
- ✔ Poor fuel economy and a noticeable loss of power.
- ✔ Intermittent issues that seem to disappear and then return.
- ✔ Failure to communicate with a diagnostic scan tool.
The Importance of VIN Programming
Simply swapping a PCM on these GM vehicles is not possible due to the integrated Vehicle Anti-Theft System (VATS or Passlock). The PCM is electronically tied to your specific vehicle’s keys and security system. This is why we offer a crucial service: we flash this module with the latest GM software updates and program it specifically to your vehicle’s VIN before we ship it. This ensures the module will communicate correctly with the other systems in your car, saving you a trip to the dealership and expensive programming fees. All you need to do is provide us with your 17-digit VIN upon purchase.
Installation is Straightforward
Once you receive your pre-programmed module, the physical installation is typically simple. After disconnecting the battery, you’ll locate your old PCM (often in the engine bay, inside the air filter housing), disconnect the wiring harnesses, and swap in the replacement unit. After reconnecting the battery, you will need to perform a simple security relearn procedure, which can usually be done without any special tools. This procedure re-syncs the new PCM to your vehicle’s keys and security system, allowing the engine to start and run.
Frequently Asked Questions
What exactly does the Powertrain Control Module do?
The PCM is your vehicle’s main computer. It takes data from sensors all over the engine and drivetrain to control fuel delivery, spark timing, transmission shifting, and emissions systems for optimal performance and efficiency.
Is this part ready to install out of the box?
Yes, this PCM comes programmed to the VIN you provide. However, you will need to perform a security relearn procedure after installation to sync the module with your car’s anti-theft system. This typically involves a series of key cycles and takes about 30 minutes.
How do I provide my VIN?
After you complete your purchase, you can send us a message with your 17-digit Vehicle Identification Number (VIN). We cannot ship your part until we receive this information, as the programming is essential for the part to function.
Is this a new or used part?
This is a high-quality, tested, and fully functional used OEM part that has been sourced from a salvaged vehicle. It offers the same performance and reliability as a new part at a fraction of the cost.
Will this fix my transmission shifting problems?
In many cases, yes. The PCM also controls the transmission’s electronic solenoids. If your shifting issues are caused by faulty signals from the computer, this replacement module can resolve them. However, it will not fix internal mechanical failures within the transmission itself.