Is Your Workhorse Truck Sidelined? Get it Running Right.
There’s nothing more frustrating than a truck that won’t start or runs erratically, especially when it’s a powerhouse like the 2009-2010 Sierra 3500. As a mechanic with over two decades of experience under the hood of these GM trucks, I’ve seen it all. A faulty Engine Control Module (ECM) can bring your entire operation to a halt, presenting symptoms that can be confusing and costly to misdiagnose. If your Sierra is experiencing intermittent stalling, a persistent check engine light with communication codes, or a complete no-start condition, the ECM is a primary suspect.
Common Symptoms of a Failing GM ECM:
- โ No communication with your scan tool
- โ Engine cranks but will not start
- โ Unexplained check engine lights (P0601, P0606)
- โ Poor fuel economy and rough idling
- โ Harsh or incorrect shifting patterns
- โ Apparent failure of multiple sensors at once
The Direct-Fit Solution: A Pre-Programmed 2009-2010 Sierra 3500 ECM
Forget expensive dealership visits and the hassle of finding a shop that can program a new module. This is a direct replacement Engine Control Module, part number 12629009 (also compatible with 12625455), that arrives at your door ready for installation. We take the guesswork out of the repair. Simply provide us with your vehicle’s VIN during checkout, and our technicians will flash the module with the latest, most stable GM-approved software specific to your truck. This ensures all systems, from the 6.0L engine to the transmission, operate exactly as the factory intended.
Expert Pro Tip from a 20-Year Tech
Before you replace your ECM, do a quick visual inspection of the main engine-to-chassis ground straps. On many of these Sierra and Silverado trucks, a corroded or loose ground on the driver’s side of the engine block can cause intermittent power to the ECM, mimicking a complete failure. I’ve seen customers spend hundreds on diagnostics when a simple wire brush and a wrench would have fixed the issue. A clean, tight ground is essential for any computer module to function correctly.
Plug-and-Play Installation: Get Your Truck Back on the Road
You don’t need to be a master technician to complete this job. With basic hand tools, you can have your Sierra 3500 running again in under an hour. The ECM is typically located in the front left (driver’s side) of the engine compartment.
- Safety First: Disconnect the negative terminal from your truck’s battery.
- Locate the ECM: Find the module on the driver’s side of the engine bay, near the fender.
- Disconnect Connectors: Carefully unclip the wiring harness connectors. These have locking tabs that need to be released before pulling. Do not force them.
- Unbolt the Module: Remove the bolts securing the ECM to its bracket.
- Install the New ECM: Mount your new, pre-programmed module in place and secure it with the bolts.
- Reconnect Everything: Firmly plug the wiring harnesses back in until they click, then reconnect the negative battery terminal.
- Perform Security Relearn: You may need to perform a simple key-cycle security relearn. Turn the key to the ‘ON’ position for 10-15 minutes (or until the security light goes out), turn it off for 10 seconds, and repeat two more times. Your truck should then start and run normally.
By ordering this pre-programmed module, you are getting a reliable, cost-effective solution that restores the brain of your vehicle. This module is not just for the Sierra; it’s the correct component for a wide range of GM vehicles from 2009-2010, including the Silverado, Suburban, Tahoe, Express vans, and even the Escalade. Ensure you match part number 12629009 or 12625455 to confirm compatibility.