Is Your GM Vehicle Running Poorly? The PCM Might Be the Culprit.
If you’re experiencing frustrating issues like a persistent Check Engine Light, erratic engine behavior, stalling, or poor fuel economy in your 1999-2000 Buick LeSabre or another compatible GM vehicle, a failing Powertrain Control Module (PCM) is a likely cause. The PCM is the central computer of your vehicle, responsible for managing everything from fuel injection and ignition timing to transmission shifting. When it fails, it can cause a wide range of problems that are often difficult to diagnose. This replacement PCM, part number 09361735, is the definitive solution to restore your vehicle’s performance and reliability.
From the Diagnostic Bay
We had a 1999 Pontiac Bonneville come into the shop with a complaint of intermittent stalling at stoplights and a weird, delayed shift between 2nd and 3rd gear. There were no consistent trouble codes, just a history of random misfire and communication loss codes that would come and go. We checked the wiring, sensors, and grounds—everything looked solid. On a hunch, we connected a scope to the PCM’s main power and communication lines. We noticed a significant voltage drop and signal noise whenever the engine cooling fans kicked on. The internal voltage regulator in the original PCM was failing under load, causing it to momentarily lose its mind. Swapping in a correctly programmed replacement like this one solved every single issue instantly. The customer was thrilled to have their smooth, reliable car back.
Common Symptoms of a Failing PCM
- ✔ Persistent Check Engine Light (CEL) with various or no specific codes.
- ✔ Engine stalling or shutting off unexpectedly.
- ✔ Rough idling or engine misfires.
- ✔ Noticeable decrease in fuel efficiency.
- ✔ Harsh or erratic automatic transmission shifting.
- ✔ Complete no-start condition where the engine cranks but won’t fire.
- ✔ Failure to communicate with a diagnostic scan tool.
Why Choose Our 1999-2000 LeSabre PCM?
This isn’t just a part in a box; it’s a complete, ready-to-install solution. We take a reliable, tested PCM from a salvaged vehicle and professionally flash it with the latest official GM software updates. The key is that we program it specifically to your vehicle’s 17-digit Vehicle Identification Number (VIN). This ensures that all factory settings, including engine parameters, transmission strategy, and anti-theft systems, are perfectly matched to your car. This VIN-specific programming eliminates compatibility guesswork and ensures a seamless installation process, getting you back on the road faster.
This module is a direct replacement for a wide array of popular GM vehicles from the late 90s and early 2000s, including the Buick LeSabre, Pontiac Grand Prix, Chevrolet Impala, and many more. Please verify the part number 09361735 and consult the detailed fitment list to confirm compatibility with your specific make, model, and year.
Installation and Setup
Installation is straightforward for a DIY mechanic with basic tools. The module is typically located in the engine compartment, often within the air filter housing, or under the dash. After disconnecting the vehicle’s battery, simply unplug the wiring harnesses from your old module, unbolt it, and install this replacement in its place. Once the battery is reconnected, you will likely need to perform a simple security relearn procedure (often called a Passlock or VATS relearn) to allow the vehicle to start. This procedure can usually be done without special tools and involves a series of key cycles. Instructions are widely available online for your specific model.
By providing us with your VIN at the time of purchase, you ensure that the 1999-2000 LeSabre PCM you receive is prepared for your exact vehicle configuration. This critical step saves you a trip to the dealership and the high cost of their programming services.
Frequently Asked Questions
Do I need to get this PCM programmed?
No. This PCM comes pre-programmed to your vehicle’s specific VIN. You must provide your VIN to us after purchase so we can flash the module with the correct software and calibrations before shipping it. This makes the installation process much simpler.
What is a security relearn procedure?
Most GM vehicles of this era have a vehicle anti-theft system (VATS/Passlock) that syncs the PCM to your key and ignition. When you install a new PCM, you must perform a relearn procedure so the car recognizes the new computer. It’s typically a 10-30 minute process involving turning the key to the ‘ON’ position and waiting for the security light to turn off, repeated three times. Specific instructions for your model can be easily found online.
Is this a new part?
No, this is a high-quality, 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.
Where is the PCM located on my vehicle?
The location varies by model. On many compatible vehicles like the LeSabre, Park Avenue, and Impala, it is located in the engine compartment, often inside the air filter box assembly for protection. On others, like the Cutlass or Malibu, it may be found under the center of the dash. A quick search for your specific model will confirm the exact location.
Will this fix my transmission problems?
The PCM controls both the engine and the transmission. If your shifting problems, such as harsh shifts or getting stuck in a gear, are caused by electronic control failures, then replacing the PCM can resolve them. However, it will not fix internal mechanical failures within the transmission itself.