Is Your GM Vehicle Running Out of Sorts?
If you’re dealing with a persistent Check Engine Light, rough idling, poor fuel mileage, or unpredictable transmission shifting in your 2003-2005 Chevrolet Impala or other compatible GM model, the root cause is often the Powertrain Control Module (PCM). As the central computer for your engine and transmission, when the PCM fails, it can create a cascade of frustrating and hard-to-diagnose problems. I’ve seen it hundreds of times in my shop: a customer comes in after replacing multiple sensors, only to find the core issue was the vehicle’s computer all along.
This isn’t just a replacement part; it’s a complete solution. We take the guesswork and high dealership costs out of the equation. This genuine replacement 2003-2005 Impala PCM comes professionally flashed with the latest official GM software updates, specifically programmed to your vehicle’s unique Vehicle Identification Number (VIN). This ensures perfect communication between all your vehicle’s systems and restores the performance and reliability you expect.
Case Study: A Tricky Diagnosis
A 2004 Impala with the 3.4L V6 came into my bay with a complaint of intermittent stalling at stoplights. There were no consistent trouble codes, just a random U0100 (Lost Communication with ECM/PCM) that would pop up occasionally. The owner had already replaced the crank sensor and cleaned the throttle body. After checking all the power and ground circuits to the PCM—a critical first step—I noticed the 5-volt reference signal would occasionally dip. Instead of a sensor failing, the PCM itself was internally shorting, causing the network to crash. Swapping in a VIN-programmed PCM like this one solved the problem instantly. The key is that a failing module doesn’t always throw a clear P0601 ‘bad module’ code.
Common Signs of a Failing PCM
- ✔ Persistent Check Engine Light (CEL) that won’t clear.
- ✔ Stored diagnostic trouble codes (DTCs) such as P0601, P0606, or other communication errors.
- ✔ Your vehicle fails an emissions or smog test.
- ✔ Noticeable decrease in fuel economy.
- ✔ Engine stalling, hesitating, or running rough.
- ✔ Harsh or erratic automatic transmission shifting.
- ✔ The engine cranks but refuses to start (no-start condition).
A Straightforward Guide to Installation
Replacing the PCM on these vehicles is a job most DIYers can handle. The key is our pre-programming service, which eliminates the need for expensive scan tools. After installation, you will need to perform a simple security relearn procedure.
- Safety First: Disconnect the negative terminal from your vehicle’s battery.
- Locate the PCM: On most Impalas, Monte Carlos, and similar models, the PCM is located inside the plastic air filter housing assembly in the engine bay. You will need to remove the air filter cover to access it.
- Disconnect and Remove: Carefully unplug the electrical connectors. They have locking tabs that need to be released. Once unplugged, unbolt the old PCM and remove it from the housing.
- Install the New Module: Seat the new PCM in place and secure it. Reconnect the electrical connectors firmly until they click. Reassemble the air filter housing.
- Reconnect Battery: Reattach the negative battery terminal.
- Perform Security Relearn: This step is crucial. Turn the key to the ‘ON’ position (do not start the engine) for 10-15 minutes. The ‘Security’ light on the dash should turn off. Turn the key off for 10 seconds. Repeat this cycle two more times. After the third cycle, the vehicle will be ready to start.
Verified Vehicle Compatibility
This module, part number 89017735, is a direct replacement for part numbers 12583827 and 12583826. It is guaranteed to fit the following vehicles. Please ensure your vehicle and options match the list below.
- Alero: 2003-2004 (3.4L)
- Aztek: 2003-2005
- Bonneville: 2004-2005 (3.8L)
- Century: 2003-2005
- Grand Am: 2003-2005 (3.4L)
- Grand Prix: 2003 (3.1L)
- Impala: 2003-2005 (3.4L)
- LeSabre: 2004-2005
- Malibu: 2003
- Monte Carlo: 2003-2005
- Montana: 2003-2005
- Park Avenue: 2004-2005
- Rendezvous: 2003-2005
- Silhouette: 2003-2004
- Venture: 2003-2005
Frequently Asked Questions
Do I need to do any programming after I receive this PCM?
Do I need to do any programming after I receive this PCM?
No. We flash the module with the latest GM software and program it to your specific VIN before shipping. The only step required after installation is a simple ‘Security Relearn’ procedure, which involves a few key cycles and does not require any special tools.
How do I provide my VIN?
After you complete your purchase, you will need to send us your 17-digit VIN. You can typically add it as a note to the seller during checkout or send it to us in a message referencing your order number. We cannot ship the module until we receive your VIN.
Will this 2003-2005 Impala PCM fix my check engine light?
If the check engine light is caused by an internal failure of the PCM (e.g., codes P0601, P0606) or a software-related issue, this replacement module will solve the problem. However, if the light is on due to a faulty sensor (like an O2 sensor or MAP sensor), that component will still need to be replaced.
What is the difference between a PCM, ECM, and ECU?
ECM (Engine Control Module) and ECU (Engine Control Unit) are often used interchangeably. A PCM (Powertrain Control Module) is a more advanced type that controls both the engine and the automatic transmission functions. For these GM vehicles, this module serves as the PCM.
Is this compatible with other part numbers?
Yes, this part 89017735 is a direct, compatible replacement for original part numbers 12583827 and 12583826.