Restore Your S-Series Truck’s Brainpower
If your 2003 Chevy Blazer S10 or GMC Jimmy S15 is suffering from baffling electrical gremlins, a persistent Check Engine Light, or frustrating drivability problems like stalling and rough idling, the root cause is often a failing Powertrain Control Module (PCM). As the central computer of your vehicle, the PCM governs everything from fuel mixture and ignition timing to transmission shifting. When it falters, the symptoms can be widespread and confusing. This replacement module, part number 12576106, is the definitive solution to restore your truck’s factory performance and reliability.
We take the guesswork and extra cost out of the repair. Unlike sourcing a module from a salvage yard, this unit comes professionally programmed to your truck’s specific Vehicle Identification Number (VIN). We install the latest GM-certified software, ensuring all factory drivability and emissions parameters are perfectly calibrated for your vehicle. This means no expensive trip to the dealership for programming—it arrives at your door ready for installation. This is a critical step for a successful repair, as an incorrectly programmed module will not function. Getting a reliable 2003 Blazer S10 PCM is the first step to getting your trusted truck back on the road.
Case Study: A Tricky Diagnosis
I remember a 2003 S10 with the 4.3L V6 that came into the shop on a tow truck. The owner had replaced the fuel pump, filter, and ignition coil, but it still had an intermittent no-start and would stall at random. No clear codes were stored, just a generic P1682 (Ignition 1 Switch Circuit 2). After checking all the wiring and power feeds to the PCM, we noticed the 5-volt reference signal would occasionally drop out. On a hunch, we connected a known-good PCM. The truck fired up instantly and ran perfectly for two days of testing. The original PCM had an internal failure that only appeared when it warmed up. It’s a classic example of how a faulty module can mimic other component failures, costing time and money on unnecessary parts.
Is Your Blazer Showing These Telltale Signs?
A failing PCM can manifest in various ways. If you’re experiencing any of the following, it’s a strong indicator that your module may need replacement. Look out for Diagnostic Trouble Codes (DTCs) like P0601, P0602, P0606, or U-series communication codes.
- ✔ Unexplained Check Engine Light illumination
- ✔ Vehicle refuses to start or has a hard starting condition
- ✔ Rough or erratic engine idle
- ✔ Sudden engine stalling while driving or at a stop
- ✔ Noticeable decrease in fuel economy
- ✔ Harsh or incorrect automatic transmission shifting
- ✔ Failure to pass state emissions testing
- ✔ Communication errors with diagnostic scan tools
Straightforward Swap: Your Installation Guide
Installing your new 2003 Blazer S10 PCM is a manageable job for a DIYer with basic hand tools. This module is typically located in the engine bay on the passenger side. Following these steps will ensure a smooth process.
- Safety First: Disconnect the negative terminal from your vehicle’s battery to prevent any electrical shorts.
- Locate the PCM: On the S10/Blazer/Jimmy, it’s usually on the RH (passenger) side of the engine compartment, near the firewall or inner fender.
- Disconnect Connectors: Carefully unclip and remove the wiring harness connectors from the old PCM. Inspect them for any corrosion or damaged pins.
- Remove the Old Module: Unbolt the PCM from its mounting bracket and remove it from the vehicle.
- Install the New Module: Mount your new, pre-programmed PCM into the bracket and secure the bolts.
- Reconnect Everything: Firmly plug the wiring harnesses back into the new module. Reconnect the negative battery terminal.
- Perform Security Relearn: Your vehicle is equipped with a Passlock/VATS security system. You will need to perform a simple key-cycle relearn procedure to sync the new PCM with your vehicle. This typically involves turning the key to the ‘ON’ position for 10-15 minutes, then off, and repeating two more times. Your vehicle will not start until this is completed.
Verified Compatibility for Your GM Vehicle
This module is a direct replacement for service number 12576106 and is compatible with a wide range of GM trucks, vans, and cars. Please verify your vehicle is on this list before ordering. Providing your VIN is mandatory for us to program the correct software for your specific application.
- BLAZER S10/JIMMY S15 (2003): Electronic Control Module; (RH front engine compartment)
- S10/S15/SONOMA (2003): Electronic Control Module; (RH front engine compartment), 4.3L
- ASTRO / SAFARI (GMC) (2003): Electronic Control Module; (LH front by battery)
- SIERRA 1500 PICKUP (2003): Electronic Control Module; (LH front under battery), w/4.3L
- EXPRESS / SAVANA 1500, 2500, 3500 VAN (2003): Electronic Control Module; (LH rear engine compartment)
- SILVERADO / SIERRA 2500, 3500 PICKUP (2003): Powertrain Control Module; (LH front under battery), gasoline, 8.1L
- AVALANCHE 2500 (2003): Electronic Control Module; (LH front under battery)
- SUBURBAN / YUKON XL 2500 (2003): Electronic Control Module; (LH front under battery), 8.1L
- CTS (2004): Electronic Control Module; (RH engine compartment), Base, ID 12581565
- CORVETTE (2004): Electronic Control Module; (RH engine compartment), ID 12581565
This part is also a direct replacement for the following service numbers: 12581565, 8125815650, 12570557, 12570558, 12576869, 12578127, 8125781270, 88864822, 89017733.
By choosing this pre-programmed 2003 Blazer S10 PCM, you’re not just buying a part; you’re getting a complete, reliable repair solution that saves you time, money, and the headache of a dealership visit. Order today and get your truck running like new again.
Frequently Asked Questions
Why do you need my VIN?
Your Vehicle Identification Number (VIN) contains critical information about your truck’s specific options, engine, transmission, and emissions equipment. We use the VIN to load the exact, correct GM software file onto the PCM, ensuring it functions perfectly with your vehicle’s systems right out of the box.
Is this part difficult to install?
For someone with basic mechanical skills, this is a very straightforward installation. It involves disconnecting the battery, unplugging the old module, unbolting it, and reversing the process with the new one. The most important step after installation is the security relearn procedure, which only requires using your ignition key.
Will I need any special tools for programming?
No. That’s the primary benefit of our service. The PCM arrives at your door already programmed with the latest software for your VIN. You will not need a GM Tech 2 or any other expensive scan tool for programming.
What is the security relearn procedure?
It’s a simple process to sync the new PCM to your vehicle’s anti-theft system (Passlock/VATS). It typically involves cycling the ignition key to the ‘ON’ position for about 10 minutes, three consecutive times. Detailed instructions are readily available online for your specific model, but it requires no special tools.
What if my part number doesn’t match 12576106 exactly?
GM uses many different service numbers for the same physical part. This module is a direct replacement for all the service numbers listed in the description, including 12581565, 12570557, and others. As long as your vehicle is on the compatibility list, this module will work.