Restore Peak Performance to Your GM Truck or SUV
Is your 2003 Chevy Blazer, GMC Jimmy, or another compatible GM vehicle acting up? If you’re dealing with a persistent Check Engine Light, frustrating stalling, erratic shifting, or a no-start condition, the problem often points directly to a failing Powertrain Control Module (PCM). As the ‘brain’ of your vehicle, the PCM is responsible for managing everything from fuel delivery and spark timing to transmission shifting. When it fails, the symptoms can be unpredictable and difficult to diagnose. This replacement PCM, part number 12570558, is the reliable, straightforward solution to get your vehicle running right again.
We take the guesswork and dealer expense out of the equation. Before this module ships, we will program it with the latest official GM software updates using the unique Vehicle Identification Number (VIN) you provide. This ensures that the module is a perfect match for your vehicle’s specific configuration, making installation a simple plug-and-play process for a DIYer or a professional mechanic.
A Technician’s Notebook: The Case of the Intermittent S10
I had a 2003 Chevy S10 with the 4.3L V6 in my bay that was a real head-scratcher for its owner. It would randomly fail to start, but only after it was warm. No codes were stored initially. After several diagnostic tests, we noticed the 5-volt reference signal to the sensors would occasionally drop out during cranking. This is a classic sign of an internal PCM failure, often caused by heat-stressed solder joints or failing capacitors after years of service. Swapping in a pre-programmed PCM like this one solved the problem instantly. The owner was back on the road the same day without a tow to the dealership.
Is Your Vehicle Showing These Signs of PCM Failure?
A faulty PCM can manifest in many ways. If you’re experiencing any of the following, a replacement module is likely the solution you need:
- ✔ Persistent Check Engine Light with communication error codes (e.g., U0100) or internal module failure codes (e.g., P0601, P0602, P0606).
- ✔ Vehicle will not start or starts and immediately stalls.
- ✔ Poor fuel economy and decreased engine power.
- ✔ Harsh or erratic automatic transmission shifting.
- ✔ Misfires or rough idling that can’t be traced to spark plugs or coils.
- ✔ Inconsistent or non-functional gauges on the instrument cluster.
A Straightforward Guide to Installation
Replacing the PCM in most of these GM vehicles is a job you can do in your own driveway. The key is a safe and methodical approach. While specific locations vary, the general process for installing your 2003 Blazer S10 PCM is as follows:
- Safety First: Always disconnect the negative terminal from your vehicle’s battery and wait at least 10 minutes to allow the system to fully discharge.
- Locate the PCM: On the Blazer/Jimmy/S10, the PCM is typically located in the engine bay on the right-hand (passenger) side. On trucks and vans, it’s often on the driver’s side near the battery.
- Disconnect the Connectors: Carefully unclip and remove the wiring harness connectors. These connectors have locking tabs; never force them. Inspect the pins for any corrosion or damage.
- Remove the Old Module: Unbolt the old 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 securely re-fasten the bolts.
- Reconnect Everything: Plug the wiring harnesses back into the new PCM until they click securely in place. Reconnect the negative battery terminal.
- Perform Security Relearn: You will likely need to perform a simple security relearn procedure (often called a ‘key-cycle relearn’) to sync the new PCM with your vehicle’s anti-theft system. This typically takes about 30 minutes and requires no special tools.
Verified Vehicle Compatibility
This module is a direct replacement for a wide range of GM vehicles. Please verify your model and options below. This part is compatible with service numbers: 12581565, 8125815650, 12570557, 12570558, 12576106, 12576869, 12578127, 8125781270, 88864822, and 89017733.
- ASTRO 03: Electronic Control Module; (LH front by battery)
- AVALANCHE 2500 03: Electronic Control Module; (LH front under battery)
- BLAZER S10/JIMMY S15 03: Electronic Control Module; (RH front engine compartment)
- CTS 04: Electronic Control Module; (RH engine compartment), Base, ID 12581565
- CORVETTE 04: Electronic Control Module; (RH engine compartment), ID 12581565
- EXPRESS/SAVANA VANS 1500/2500/3500 03: Electronic Control Module; (LH rear engine compartment)
- S10/S15/SONOMA 03: Electronic Control Module; (RH front engine compartment), 4.3L
- SAFARI (GMC) 03: Electronic Control Module; (LH front by battery)
- SIERRA/SILVERADO 1500 03: Electronic Control Module; (LH front under battery), w/4.3L
- SIERRA/SILVERADO 2500/3500 03: Electronic Control Module; (LH front under battery), gasoline, 8.1L
- SUBURBAN 2500 03: Electronic Control Module; (LH front under battery), 8.1L
- YUKON XL 2500 03: Electronic Control Module; (LH front under battery), 8.1L
Frequently Asked Questions
How do I provide my VIN for programming?
After you complete your purchase, you will receive instructions to reply with your 17-digit VIN. We cannot ship the module until we receive this information, as the programming is essential for the part to function in your vehicle.
What is a security relearn and is it difficult?
A security relearn syncs the new PCM to your vehicle’s anti-theft system. It’s a simple procedure you can do yourself. It typically involves turning the key to the ‘ON’ position for 10 minutes, then ‘OFF’ for 10 seconds, and repeating this cycle three times. We include easy-to-follow instructions.
Will I need to do a CASE relearn?
In some cases, a Crankshaft Variation Relearn (CASE) may be needed to clear a P1336 code. This procedure requires a high-level scan tool and can be performed by most local repair shops if necessary. However, many vehicles do not require it after a PCM replacement.
Is this part a direct fit for my 2003 Blazer S10 PCM?
Yes. This module is a direct-fit replacement for the original PCM on a 2003 Chevy Blazer S10 and GMC Jimmy S15. Once programmed to your VIN, it will function exactly like the original factory unit.
Does this module come with a warranty?
Yes, all of our powertrain control modules come with a standard warranty that covers any defects in the module itself. Please see our warranty page for full details and terms.