Is Your Work Van Sidelined? Get Back on the Road Fast.
If your 2016 Chevrolet Express 3500 is suddenly giving you troubleโstalling at intersections, refusing to start, or running with a frustrating lack of powerโthe problem often points directly to a failing Engine Control Module (ECM). As a mechanic with over two decades of experience under the hood, I’ve seen how a faulty ECM can bring a reliable workhorse to a complete stop, costing you time and money. This isn’t just a part; it’s the central computer for your engine, and when it fails, nothing works right.
The Direct Solution: A VIN-Programmed 2016 Express 3500 ECM
This isn’t a generic, one-size-fits-all computer. This is a direct replacement ECM, part number 12668991, that we program specifically for your vehicle using your VIN. This critical step ensures that the module is loaded with the correct GM factory software and calibrations for your van’s specific engine (4.8L or 6.0L), transmission, and factory options. The result is a component that works correctly the moment you install it, eliminating the need for an expensive and time-consuming trip to the dealership for programming.
From the Shop Floor: “A contractor’s 2016 Express 3500 came in last week with these exact symptoms. It had an intermittent no-start and was throwing a P0606 code (ECM Processor Fault). He’d already replaced the battery and checked the alternator, but the problem persisted. After a quick diagnostic, we confirmed the internal processor in the original ECM was failing. A pre-programmed replacement like this one is the most efficient repair. We swapped it out, and he was back on the road to his next job in under an hour, completely avoiding dealer service bays.”
Common Symptoms of a Failing GM Engine Computer
If you’re experiencing any of the following, a bad ECM is a likely culprit:
- โ Check Engine Light is on with communication-related codes (U-codes) or internal processor faults.
- โ Vehicle has a no-start or hard-start condition.
- โ Engine is stalling or running rough for no apparent reason.
- โ Noticeable drop in fuel economy.
- โ Transmission shifting erratically or harshly.
- โ Loss of communication with your scan tool.
Plug-and-Play Installation: No Dealer Visit Required
Installing this module is straightforward for a DIYer or any professional mechanic. Just follow these simple steps to get your vehicle running properly again.
- Safety First: Always disconnect the negative terminal from your vehicle’s battery before beginning work.
- Locate the ECM: On the 2016 Express and Savana vans, the ECM is typically found in the left-hand rear of the engine compartment.
- Disconnect Connectors: Carefully release the locking tabs and unplug the wiring harness connectors from the old module. Inspect the connectors for any signs of corrosion or damage and clean if necessary.
- Remove Old Module: Unbolt the faulty ECM from its mounting bracket.
- Install New Module: Securely mount your new, pre-programmed ECM in place of the old one.
- Reconnect Everything: Plug the wiring harness connectors firmly into the new module until they click. Reconnect the negative battery terminal.
- Final Step: Start the engine. The vehicle is now ready to drive. In some cases, a security or idle relearn procedure may be necessary, which can often be completed by following simple key-on/key-off cycles.
Guaranteed Compatibility & Peace of Mind
This ECM is a direct replacement for a wide range of GM vehicles and interchanges with multiple part numbers, ensuring you get the right component. Please provide your VIN upon purchase so we can guarantee a perfect software match.
Replaces Part Numbers: 12668866, 12668994, 12643636, 12663405, 12670335, 22819494, 12692200
Broad Vehicle Fitment Includes:
- Chevrolet Express & GMC Savana Vans (2500/3500)
- Chevrolet Silverado & GMC Sierra Pickups (2500/3500)
- Chevrolet Cruze, Sonic, Spark, Trax, Volt
- Buick Encore
- Cadillac ELR
- And more (see detailed fitment list)