Restore Your GM Truck’s Brain and Get Back on the Road with Confidence
As a technician with over two decades of diagnostic experience, I’ve seen firsthand how a failing Powertrain Control Module (PCM) can turn a reliable truck into a source of constant frustration. If your 2003 Chevy S10 Blazer or GMC S15 Jimmy is suffering from erratic behavior, poor performance, or won’t start at all, the problem often lies with this critical component. This isn’t just a replacement part; it’s a complete, hassle-free solution. We take the guesswork and dealer-dependency out of the equation by pre-programming this module specifically for your vehicle using your VIN. It arrives at your door loaded with the latest GM software updates, ready for a straightforward installation.
Case Study: The Ghost in the Machine
I remember a 2003 GMC Sonoma with the 4.3L V6 that came into the shop with a maddeningly intermittent stalling problem. The owner had already replaced the fuel pump and ignition module. It would run perfectly for days, then die at a stoplight without warning. No consistent codes were stored, just a history of random communication errors. After hours of checking wiring and grounds, we put a scope on the PCM’s 5-volt reference line. We noticed that on hot days, the voltage would become unstable just before a stall. A failing internal processor in the original PCM was getting heat-sensitive. Swapping in a quality, correctly programmed module like this one solved the problem instantly. It’s a classic example of how a faulty 2003 Blazer S10 PCM can mimic other, more common failures.
Is Your Truck or Van Showing These Symptoms?
A failing PCM can cause a wide range of issues, from subtle to severe. If you’re experiencing any of the following, there’s a strong chance your engine computer is the culprit. Many of these symptoms are often accompanied by Diagnostic Trouble Codes (DTCs) like P0601, P0602, P0606, or various U-codes (communication errors).
- ✔ Check Engine Light is illuminated for internal module failure.
- ✔ The engine cranks but refuses to start.
- ✔ Unexplained stalling or rough, inconsistent idling.
- ✔ A noticeable drop in fuel economy.
- ✔ Harsh or erratic automatic transmission shifting.
- ✔ Failure to pass an emissions/smog test.
- ✔ No communication with your scan tool.
A Straightforward Guide to Installation
Installing your new 2003 Blazer S10 PCM is a job most DIYers can handle in under an hour. The key is patience and following the proper procedure. For the S10/Blazer/Jimmy/Sonoma, the PCM is typically located in the engine compartment on the right-hand (passenger) side.
- Safety First: Always disconnect the negative terminal from your vehicle’s battery and secure it away from the post to prevent any accidental reconnection.
- Locate the PCM: On your S10/Blazer, find the module on the passenger side of the engine bay. It will have several large multi-pin electrical connectors.
- Disconnect the Connectors: Carefully release the locking tabs or levers on each wiring harness connector and pull them straight out from the module. Avoid pulling on the wires themselves.
- Remove the Old Module: Unbolt the PCM from its mounting bracket. Keep the hardware, as you may need to reuse it.
- Install the New Module: Seat the new, pre-programmed PCM into the bracket and secure it with the mounting bolts.
- Reconnect Everything: Firmly plug the wiring harnesses back into the correct sockets on the new module. Ensure the locking levers click into place. Reconnect your negative battery terminal.
- Perform Security Relearn: Your vehicle may require a simple security relearn procedure to recognize the new PCM. This typically involves turning the key to the ‘ON’ position for 10-15 minutes. A Crankshaft Variation (CASE) relearn may also be needed for optimal performance, which can be done with a capable scan tool.
Guaranteed Fitment for Your GM Vehicle
This module is a direct replacement for part number 89017733 and is compatible with numerous other service numbers. We guarantee it will fit and function correctly in the following vehicles, provided the options match. Please verify your vehicle is on this list before ordering.
- ✔ 2003 Astro / Safari (GMC): Electronic Control Module; (LH front by battery)
- ✔ 2003 Avalanche 2500: Electronic Control Module; (LH front under battery)
- ✔ 2003 Blazer S10 / Jimmy S15: Electronic Control Module; (RH front engine compartment)
- ✔ 2004 CTS: Electronic Control Module; (RH engine compartment), Base, ID 12581565
- ✔ 2004 Corvette: Electronic Control Module; (RH engine compartment), ID 12581565
- ✔ 2003 Express / Savana Van (1500/2500/3500): Electronic Control Module; (LH rear engine compartment)
- ✔ 2003 S10 / S15 / Sonoma Pickup (4.3L): Electronic Control Module; (RH front engine compartment)
- ✔ 2003 Sierra / Silverado 1500 Pickup (4.3L): Electronic Control Module; (LH front under battery)
- ✔ 2003 Sierra / Silverado 2500/3500 Pickup (8.1L Gas): Electronic Control Module; (LH front under battery)
- ✔ 2003 Suburban 2500 (8.1L): Electronic Control Module; (LH front under battery)
- ✔ 2003 Yukon XL 2500 (8.1L): Electronic Control Module; (LH front under battery)
Frequently Asked Questions
Frequently Asked Questions
Why do you need my VIN?
Your Vehicle Identification Number (VIN) is essential. It allows us to load the exact, correct factory software for your vehicle’s specific engine, transmission, and emissions equipment. This ensures perfect compatibility and performance, just like a new part from the dealer.
Is this part difficult to install?
For most individuals with basic hand tools, the physical installation is very straightforward. The module is typically easy to access. The only additional step might be a simple security relearn procedure, which does not require special tools.
Will this fix my Check Engine Light?
If the Check Engine Light is on due to an internal PCM failure (like code P0601), then yes, this part is the correct fix. However, if the light is on for another reason (e.g., a bad oxygen sensor), you will still need to repair that separate issue.
What is a CASE Relearn and is it required?
A Crankshaft Position System Variation (CASE) relearn synchronizes the new PCM with the crankshaft position sensor. While many vehicles will run fine without it, performing a CASE relearn with a compatible scan tool is recommended for optimal engine timing, misfire detection, and smooth performance.
Is this a brand new part?
This is a high-quality, tested, and reliable replacement part that has been programmed with the latest software to restore your vehicle’s original functionality. It is guaranteed to perform correctly.