Programmed 2005 Rainier Engine Control Module | ECM 12596771

Is your 2005 Buick Rainier or other compatible GM vehicle suffering from frustrating, hard-to-diagnose engine problems? Issues like random stalling, a persistent check engine light, or a complete no-start condition often point directly to a failing Engine Control Module (ECM). As the ‘brain’ of your vehicle, a faulty ECM can disrupt everything from fuel delivery and spark timing to transmission shifting. Stop throwing parts at the problem and get the definitive solution with this professionally programmed ECM, part number 12596771.

For over 20 years in the shop, I’ve seen countless vehicle owners and even other technicians get stumped by intermittent electronic gremlins. The culprit is frequently the ECM, which can fail internally without leaving obvious physical clues. This replacement 2005 Rainier Engine Control Module arrives at your door ready for installation. We handle the critical programming for you—using your vehicle’s VIN, we load the latest GM-certified software updates. This ensures perfect communication with your vehicle’s other systems, restores factory performance, and eliminates the need for an expensive trip to the dealership for programming.

Is Your Vehicle Showing These Symptoms?

• ✔ Unexplained Check Engine Light with codes like P0601, P0602, or P0606.
• ✔ Engine cranks but refuses to start.
• ✔ Intermittent stalling or rough idling, especially when warm.
• ✔ Noticeable decrease in fuel economy and engine power.
• ✔ Communication errors with diagnostic scan tools.
• ✔ Erratic automatic transmission shifting behavior.

A Straightforward Guide to Installation

1. ✔ Safety First: Always disconnect the negative terminal from your vehicle’s battery before starting any electronic work.
2. ✔ Locate the ECM: On most of these GM SUVs, the ECM is located in the engine bay on the driver’s side, near the air filter box.
3. ✔ Disconnect Connectors: Carefully release the locking tabs and unplug all wiring harness connectors from the old module. Avoid forcing them.
4. ✔ Remove the Old Module: Unbolt the mounting brackets holding the original ECM in place and remove it from the vehicle.
5. ✔ Install the New Module: Mount your new, pre-programmed ECM in the same location and securely re-fasten the bolts.
6. ✔ Reconnect and Secure: Plug the wiring harnesses firmly into the new module until they click into place. Reconnect the negative battery terminal.
7. ✔ Perform Security Relearn: You will need to perform a simple security relearn procedure (often called a Passlock relearn) to sync the new ECM with your vehicle’s anti-theft system. This typically involves turning the key to ‘ON’ for 10-15 minutes, then ‘OFF’, and repeating a few times. Your vehicle will not start until this is completed.

By choosing this pre-programmed 2005 Rainier Engine Control Module, you’re not just buying a part; you’re getting a complete, hassle-free solution designed to get your vehicle running reliably again. It’s the same trusted fix I’ve used in my own service bay for years.

Verified Vehicle Compatibility

This module is a direct-fit replacement for the following vehicles equipped with the specified engines. It is a compatible replacement for service numbers: 12578554, 12596771, 12597191, 12597883, and 19210071.

• ✔ 2005 Buick Rainier: 5.3L (LH engine)
• ✔ 2005 Chevrolet Corvette: (RH engine compartment)
• ✔ 2005 Chevrolet SSR: (next to air box)
• ✔ 2005 Chevrolet Trailblazer EXT: 5.3L (LH engine)
• ✔ 2005 GMC Envoy: 5.3L (LH engine)
• ✔ 2005 GMC Envoy XL: 5.3L (LH engine)
• ✔ 2005 GMC Envoy XUV: 5.3L (LH engine)
• ✔ 2005 Isuzu Ascender: 5.3L (LH engine)
• ✔ 2005 Pontiac GTO: main (LH engine)
• ✔ 2005 Saab 9-7X: 8 cylinder (LH engine)