Our 2012 C (trim level 3 with the keyless entry fob) has intermittent door locking problems. At first it was the driver door where the locking motor wouldn't respond and we used the mechanical key. All the other doors would follow the mechanical lock/unlock so all was okay. I thought it was the commonly failing actuator or motor but after a few weeks the problem switched over to the passenger door, now the driver door makes a satisfying, healthy sounding "clack" but the passenger side doesn't do anything. Now we use the mechanical lever in the door to lock/unlock the passenger side. It doesn't matter whether I use the handle, keyfob or mechanical key on the driver side. OBD II doesn't report any faults. It seems strange that the intermittency would jump from one side to another, I couldn't find a wiring diagram that suggests a root cause? Any ideas, are there relays or wire harness connectors I should look at? At this point I'm fairly confident I don't have to take any door panels off but not sure where to look next. Thanks, Andrew
AFAIK there are no relays- these are directly driven by the body control unit. There are of course a few harness connections along the way. https://techinfo.toyota.com sells temporary access to the interactive wiring diagram. It's extremely detailed and easy to use. Well worth the $20 on a car with this many wires. Good luck!
I wouldn't rule out the actuator problem when doing your troubleshooting. Each of my locks started it gradually and come and go at first. Some have proceeded rapidly to total failure, others have returned to perfect working order. My rear left lock was showing the problem intermittently for a few months at one point but has been working fine for a year or two now. It will shortly be my last remaining original lock actuator.
