Is Your Sierra 3500 Running Rough or Not Starting at All?
When your workhorse truck is down, every minute counts. If you’re dealing with a persistent Check Engine Light, erratic engine behavior, stalling, or a complete no-start condition, a failing Engine Control Module (ECM) is a very likely culprit. The ECM is the brain of your truck’s 6.0L engine, and when it fails, it can cause a cascade of frustrating and costly problems. Don’t let a faulty computer keep you off the road or stuck with a massive dealership repair bill.
The Simple, Direct-Fit Solution
This is a genuine GM Engine Control Module, part number 12670335, that arrives at your door fully programmed to your truck’s specific Vehicle Identification Number (VIN). We handle the complicated part for you. Using the latest GM software updates, we flash the module so it’s a true plug-and-play replacement. This means no expensive towing, no waiting for a dealership appointment, and no additional programming fees. You can get your truck back to work quickly and confidently.
From the Shop Floor: A Real-World Scenario
“A customer’s 2014 Sierra 3500 came in on a flatbed last monthโit would crank but not start, and the owner had already replaced the fuel pump. After a quick diagnostic scan, we saw no communication with the ECM. Before ordering a new module, we checked the wiring harness. We found that a wire for the #3 ignition coil had chafed against the engine block, creating a direct short to ground. This short is what fried the driver circuit inside the original ECM. We repaired the wire, installed a new pre-programmed ECM like this one, and the truck fired right up. Itโs a crucial reminder: always check for external faults before condemning the computer itself. A 10-minute inspection can save you from damaging your new part.”
Common Symptoms of a Failing ECM:
- โ Check Engine Light is on with various communication or sensor codes
- โ Engine cranks but will not start
- โ Stalling, hesitation, or rough idling
- โ Poor fuel economy and loss of power
- โ Harsh or incorrect automatic transmission shifting
- โ Communication errors with diagnostic scan tools
Easy Installation: Get Back on the Road Fast
Installing your new 2012-2016 Sierra 3500 ECM is a straightforward process that you can do with basic hand tools. Since we’ve already handled the programming, the complex part is done.
- Safety First: Disconnect the negative terminal from your truck’s battery.
- Locate the ECM: On the Sierra 3500, the ECM is typically found in the engine compartment on the driver’s side, near the fender or firewall.
- Disconnect Connectors: Carefully release the locking tabs and unplug the large electrical connectors from the old module. Inspect the connectors for any corrosion or bent pins and clean them if necessary.
- Swap the Modules: Unbolt the old ECM from its mounting bracket and secure the new one in its place.
- Reconnect Everything: Plug the electrical connectors firmly into your new ECM until they click into place. Reconnect the negative battery terminal.
- Final Step: Turn the key to the ‘ON’ position for 10-15 seconds before starting the engine. This allows the other modules in the vehicle to recognize the new ECM. Your truck is now ready to go!
Guaranteed Compatibility
This module is a direct replacement for a wide range of GM vehicles and supersedes multiple part numbers. By providing your VIN, you ensure that the software loaded onto this computer is precisely correct for your 2012-2016 Sierra 3500 with the 6.0L engine and all its specific options. This part is a verified replacement for part numbers: 12668866, 12668994, 12643636, 12663405, 12670335, 22819494, and 12692200.