Restore Your Truck’s Performance and Reliability
Is your 2003 Chevrolet Avalanche 2500 giving you headaches? If you’re dealing with a persistent check engine light, rough idling, stalling, or poor fuel economy, the problem often points directly to a failing Powertrain Control Module (PCM). As a technician with over two decades of diagnostic experience, I’ve seen countless GM trucks sidelined by faulty engine computers. This isn’t just an inconvenience; it affects your truck’s core performance, safety, and emissions. This replacement PCM is the definitive solution, arriving at your door fully programmed with the latest GM software for your specific vehicle.
A Technician’s Notebook: The Ghost in the Machine
I remember a 2003 Silverado 2500 with the 8.1L—same platform as your Avalanche—that came into my shop with the strangest set of problems. The owner reported random stalling, transmission shifting hard out of nowhere, and gauges that would occasionally drop to zero and then pop back up. He’d already replaced the battery and alternator. After hours of chasing wires, my scan tool finally caught the PCM dropping communication intermittently. The internal processor was failing. We swapped in a VIN-programmed module just like this one, performed the quick security relearn, and the truck ran perfectly. It’s a classic case where a single component mimics a dozen different failures, and a quality, pre-programmed PCM is the only real fix.
Is Your Truck Showing These Symptoms?
A failing PCM can manifest in numerous ways. If you’re experiencing any of the following, it’s a strong indicator that your engine’s main computer needs attention. Don’t let these issues get worse and potentially cause damage to other components like the catalytic converter.
- ✔ Check Engine Light is on with codes like P0601 (Internal Control Module Memory Check Sum Error) or P0606 (PCM Processor Fault).
- ✔ The engine cranks but refuses to start.
- ✔ Unexplained drops in fuel efficiency.
- ✔ The engine runs rough, misfires, or stalls unexpectedly.
- ✔ Harsh or erratic automatic transmission shifting.
- ✔ Failure to pass state emissions testing.
- ✔ Communication errors with your diagnostic scan tool.
A Straightforward Guide to Installation
One of the biggest benefits of this module is that it’s designed for a straightforward swap. Because we program it to your VIN before shipping, you skip the expensive trip to the dealership. Here’s a general guide to get you back on the road:
- Safety First: Always disconnect the negative terminal from your vehicle’s battery before starting any electrical work.
- Locate the PCM: On your 2003 Avalanche 2500, the PCM is located on the driver’s side, in the engine bay, under the battery tray. You will need to remove the battery to access it.
- Disconnect Connectors: Carefully unclip the electrical wiring harnesses from the old PCM. These connectors have locking tabs, so be gentle to avoid breaking them.
- Remove the Old Module: Unbolt the PCM from its mounting bracket. Keep the hardware as you may need it for the new module.
- Install the New PCM: Mount the new, pre-programmed module in place and securely fasten it. Reconnect the wiring harnesses, ensuring they click firmly into place.
- Reconnect Battery: Reinstall your battery and connect the negative terminal.
- Perform Security Relearn: You will likely need to perform a simple security relearn procedure. This typically involves turning the key to the ‘ON’ position for 10-15 minutes, then off, and repeating two more times. This allows your vehicle’s anti-theft system to recognize the new PCM.
Verified Vehicle Compatibility
This module, part number 89017733, is a direct replacement for a wide range of GM vehicles. It is compatible with multiple service numbers including 12581565, 12570557, 12576106, and 88864822. Please verify your vehicle is on the list below for guaranteed fitment.
ASTRO 03 (LH front by battery)
BLAZER S10/JIMMY S15 03 (RH front engine compartment)
CTS 04 (RH engine compartment), Base, ID 12581565
CORVETTE 04 (RH engine compartment), ID 12581565
EXPRESS/SAVANA 1500, 2500, 3500 VANS 03 (LH rear engine compartment)
S10/S15/SONOMA 03 (RH front engine compartment), 4.3L
SAFARI (GMC) 03 (LH front by battery)
SIERRA 1500 PICKUP 03 (LH front under battery), w/4.3L
SIERRA 2500/3500 PICKUP 03 (LH front under battery), gasoline, 8.1L
SILVERADO 2500/3500 PICKUP 03 (LH front under battery), gasoline, 8.1L
SUBURBAN 2500 03 (LH front under battery), 8.1L
YUKON XL 2500 03 (LH front under battery), 8.1L
Frequently Asked Questions
What do you mean by “VIN Programmed”?
When you purchase, you provide us with your vehicle’s 17-digit Vehicle Identification Number (VIN). We use this number to load the exact, correct, and most current factory software from GM for your truck’s specific configuration. This ensures perfect compatibility and function right out of the box, eliminating the need for a dealer to program it.
Will I need to do anything else after installation?
Besides the simple security relearn procedure (instructions included), some vehicles may require a Crankshaft Variation Relearn (CASE Relearn). This can be done with many mid-range scan tools or by a local mechanic and ensures the PCM accurately reads the crankshaft position sensor to prevent misfire codes.
Is this a new or used part?
This is a high-quality, inspected, and tested OEM part that has been professionally programmed to function as a reliable replacement for your original module. It meets or exceeds original factory specifications.
How do I find my PCM service number to check compatibility?
Your original PCM will have a sticker on it with a service number (often abbreviated as SERV. NO.). You can cross-reference that number with the list in our description (e.g., 12581565, 89017733) to confirm a match. However, providing your VIN is the most accurate way to guarantee you get the correct part and programming.
What information do you need from me after I order?
After you place your order, we will need your 17-digit VIN to program the module. Please have it ready to ensure there are no delays in shipping your part.