2014 Rear Lift Gate Malfunction Help

[venajeff]

This is a long shot, but maybe someone else has had the same problem and knows how to fix it.

I own a 2014 TC Platinum, and the rear lift gate is malfunctioning. It started out by not allowing me to open the rear lift door when when the button was pressed on the door, and it would only do this intermittently. Now the problem has progressed and it is now triggering an open for the rear door all on its own at random times. 

I have already tried replacing the Rear Lift Gate locking module (cheap and easy to change). The dealer thinks the only other option is to replace the BCM (body control Module) but they are not positive that it will fix the problem. As this is rather expensive, and it looks like it has to be done by a dealer because it will have to be reprogrammed, I am looking for other options or ideas.

Thanks.

[Don Ridley]

The wiring diagram shows the lift gate latch switch sends a signal to the BCM when pressed. The BCM then sends  12v power to the latch motor to open the lift gate.

 

If the BCM is faulty it is either responding to a phantom switch input or the non-serviceable relay in the BCM  is faulty. Besides the lift gate switch, the only other mechanical failure could be the wire between the switch and BCM. If this wire is shorting to the vehicle chassis, the BCM will read this as a request to open the lift gate. BUT...if the lift gate is opening WHEN THE DOORS ARE LOCKED, the BCM is surely the problem.

 

Due to the cost, I would check the  wire between the two components. A tech with the schematic can do this in 15 minutes. A new BCM can only be programmed by a dealer.

 

[G B L]

What happens when you wiggle the rubber loom that goes between the lift gate and the body? The all the wires that operate the components in the lift gate pass through that bell owes. if there is a wiring harness issue that would be a good place to start.

[venajeff]

I have replaced the latch motor, no change. I have tried wiggling all the wires I can reach, inside the read door, and around the BCM. I have tried disconnecting and reconnecting all the connectors going to the BCM. The strange part with the problem is how it doesn't open when I want it to then opens on its own when I dont want it to. It is rather irritating. 

 

I am contemplating installing my own unlocking system. Using an Arduino and then a sequence you push on the button to open. I love my TC but I it is hard to justify the $ for the new BCM.

[Don Ridley]

I don't see an easy workaround in the wiring diagrams for the door lock circuits. It may be worth the trouble to download Forscan (and buy an ELM327 Bluetooth device) and read the DTCs. Maybe there is something else going on that is not obvious that will show up in the DTCs. The PC version of Forscan is free and the phone apps are about $10.