Restore Your Truck’s Performance and Reliability
Is your 2008 GMC Sierra 3500 acting up? Experiencing frustrating issues like a persistent Check Engine Light, rough idling, poor fuel economy, or even a no-start condition? In my 20+ years as a technician, I’ve seen these symptoms countless times, and they often point directly to a failing Engine Control Module (ECM). The ECM is the brain of your truck’s engine, managing everything from fuel injection and ignition timing to transmission shifting. When it fails, the whole system suffers.
Don’t let a faulty computer keep your hard-working truck off the road. This replacement Engine Control Module, part number 12622141, is the definitive solution. We take the biggest headache out of the repair process: programming. Simply provide us with your vehicle’s VIN during checkout, and our experts will flash this module with the latest, most stable software directly from GM. This ensures it’s a perfect match for your truck’s specific configuration, restoring original performance and efficiency. This isn’t just a replacement part; it’s a new lease on life for your vehicle’s powertrain.
From the Diagnostic Bay
I remember a customer with an ’08 Sierra 2500, the 6.0L model, that had the most bizarre intermittent stalling issue. He’d already replaced the crank sensor and fuel pump based on another shop’s advice, but the problem persisted. When it got to my bay, I saw no hard codes, just a history of communication loss codes (U-codes). After checking the network wiring, I suspected the ECM itself was failing internally when it got hot. We installed one of these pre-programmed modules. The customer performed the simple 10-minute security relearn at home. The truck has run flawlessly ever since. It saved him from a costly dealership tow and diagnostic fee, solving the root problem directly.
Is Your Truck Showing These Symptoms?
A failing ECM can manifest in various ways. If you’re noticing any of the following, it’s a strong indicator that your module needs attention. Often, you’ll see diagnostic trouble codes (DTCs) like P0601, P0606, or U0100.
- ✔ Check Engine Light is illuminated
- ✔ Engine cranks but refuses to start
- ✔ Unexplained drop in fuel mileage
- ✔ Rough or unstable engine idle
- ✔ Hesitation or stumbling during acceleration
- ✔ Automatic transmission shifts erratically or harshly
- ✔ Loss of communication with other vehicle modules
A Straightforward Guide to Installation
One of the best features of this 2008 Sierra 3500 ECM is that it arrives ready to install, saving you a trip to the dealership. While professional installation is always an option, a confident DIYer can handle this job.
- Safety First: Disconnect the negative terminal from your truck’s battery.
- Locate the ECM: On the 2008 Sierra 3500, the ECM is typically found on the driver’s side of the engine bay, under the battery tray. You will need to remove the battery to access it.
- Disconnect and Remove: Carefully unplug the electrical connectors. They have locking tabs that need to be released. Then, unbolt the old module from its mounting bracket.
- Install the New Module: Bolt the new ECM into place and securely plug in the electrical connectors. You should hear a ‘click’ as they lock.
- Reconnect Battery: Reinstall the battery and connect the negative terminal.
- Perform Security Relearn: This is a critical final step. Turn the key to the ‘ON’ position (don’t start the engine) for 10-12 minutes, or until the security light on the dash turns off. Turn the key off for 10 seconds. Repeat this cycle two more times (for a total of three cycles). Your truck is now ready to start.
Verified Vehicle Compatibility
This module is a direct replacement for part numbers 12612384, 12622141, and 12617568. It fits a wide range of GM vehicles. Please verify your vehicle is on this list before ordering.
AURA 08 (RH firewall), 3.5L
CAPRICE 11 ID 12612384
CORVETTE 08-09 (RH engine compartment)
CTS 08 (RH front engine compartment), 3.6L, VIN 7, ID 12612384
EQUINOX 08-09 (LH engine compartment), 3.4L
ESCALADE / ESV / EXT 08 (LH front under battery)
EXPRESS 1500 VAN 08 (LH rear engine compartment), 5.3L
EXPRESS 2500/3500 VAN 08 (LH rear engine compartment), gasoline
G6 08 (LH front engine compartment), 3.5L or 3.9L
HUMMER H2 08 (LH front under battery)
IMPALA 08 (lower part of air cleaner box), 3.5L or 3.9L
MALIBU 08 Classic & New Style, 3.5L
SAVANA 1500 VAN 08 (LH rear engine compartment), 5.3L
SAVANA 2500/3500 VAN 08 (LH rear engine compartment), gasoline
SIERRA 1500 PICKUP 08 (LH front under battery), w/o 4.3L
SIERRA 2500 PICKUP 08 (LH front under battery), 6.0L
SIERRA 3500 PICKUP 08 (LH front under battery), 6.0L
SIERRA DENALI 08 (LH front engine compartment)
SILVERADO 1500 PICKUP 08 (LH front under battery), w/o 4.3L
SILVERADO 2500/3500 PICKUP 08 (LH front under battery), 6.0L
SUBURBAN 1500/2500 08 (LH front under battery)
TAHOE 08 (LH front under battery), w/o hybrid
TORRENT 08-09 (LH engine compartment), 3.4L
VUE 08-09 3.5L
YUKON / YUKON XL 1500/2500 08 (LH front under battery), w/o hybrid
Frequently Asked Questions
Do I need any special tools to install this ECM?
No. Besides standard hand tools to access the module (like a socket set), you do not need any special scan tools for programming. We handle the programming before we ship it. You only need to perform the simple key-cycle security relearn procedure.
Is this a used part?
This is a high-quality, inspected, and tested recycled OEM part. It has been verified to be fully functional and is flashed with the newest GM software for your VIN, ensuring reliability.
What happens if I don’t provide my VIN?
Providing your VIN is essential. We cannot program and ship your module without it. The programming makes the module compatible with your truck’s specific systems, including the anti-theft system and transmission. Please enter your VIN during checkout or message it to us after your purchase to avoid delays.
Will this fix my specific problem?
This 2008 Sierra 3500 ECM is the solution for a wide range of electronic and drivability issues caused by a faulty module. While it’s a very common failure point, we always recommend a proper diagnosis by a qualified mechanic to confirm the ECM is the cause of your issue before ordering.
What if my original part number is not 12622141?
This module is also a direct replacement for part numbers 12612384 and 12617568. As long as your vehicle is on the compatibility list and you have one of these three part numbers, this module will work perfectly once programmed to your VIN.