Is Your 2003 Blazer or Jimmy Running Rough? Get the Right Fix.
If you’re dealing with a frustrating check engine light, poor fuel economy, erratic shifting, or a no-start condition in your 2003 Chevy Blazer S10 or GMC Jimmy S15, a failing Powertrain Control Module (PCM) is often the culprit. As the brain of your vehicle, when the PCM starts to fail, it can cause a cascade of confusing problems that are difficult to diagnose. I’ve seen it hundreds of times in my shop: customers replace sensor after sensor, only to find the root cause was the computer all along.
This isn’t just a replacement part; it’s a complete solution. We take the guesswork out of the repair by programming this module specifically for your truck using your Vehicle Identification Number (VIN). This means it arrives at your door with the latest GM software updates already installed, ready for a straightforward installation. You get to skip the expensive trip to the dealership for programming.
Common Symptoms of a Failing 2003 Blazer S10 PCM
A faulty engine computer can manifest in many ways. If your truck is experiencing any of the following, it’s time to inspect your PCM:
- โ Persistent Check Engine Light (CEL) with various codes
- โ Engine stalling, stumbling, or misfiring
- โ Harsh or incorrect automatic transmission shifting
- โ Complete no-start or intermittent starting issues
- โ Poor acceleration and loss of power
- โ Decreased fuel mileage
- โ Communication errors with diagnostic scan tools
Before you install your new PCM, take a moment to closely inspect the wiring harness connectors that plug into the module. Over 20+ years, moisture and heat can cause the pins to corrode or the plastic to become brittle. I had an ’03 S-10 in the bay that had intermittent misfires that wouldn’t go away. The cause was a tiny bit of green corrosion on one of the PCM connector pins, causing a poor connection. A quick clean with a terminal brush can prevent a world of headaches and ensure your new module communicates perfectly from the start.
Plug-and-Play Installation: No Dealer Visit Required
Installing your VIN-programmed PCM is a job you can do in your own driveway. For the 2003 Blazer and Jimmy, the module is conveniently located in the engine bay.
- Safety First: Disconnect the negative terminal from your vehicle’s battery.
- Locate the PCM: Open the hood and find the module on the right-hand (passenger) side of the engine compartment, typically near the firewall or inner fender.
- Disconnect Harnesses: Carefully unplug the electrical connectors from the old module. These GM connectors often have colored lever-locks or tabs that need to be released before they can be pulled straight out. Do not force them.
- Remove the Old Unit: Unbolt the old PCM from its mounting bracket.
- Install the New PCM: Secure your new, pre-programmed module onto the bracket and reconnect the wiring harnesses, ensuring they click securely into place.
- Reconnect Battery: Reattach the negative battery terminal.
- Perform Security Relearn: In many cases, you may need to perform a simple security relearn procedure to sync the new PCM with your vehicle’s anti-theft system. This usually involves turning the key to the ‘ON’ position for 10-15 minutes, then off, and repeating two more times before starting the engine.
Guaranteed Compatibility and Peace of Mind
This module is a direct replacement for a wide range of GM vehicles and is cross-compatible with multiple service numbers, ensuring you get the correct part. Simply provide your VIN at checkout, and we handle the rest.
Replaces Part Numbers: 12581565, 8125815650, 12570557, 12570558, 12576106, 12576869, 12578127, 88864822, 89017733