Kevin Moore

Hi, I have a 2012 Honda Accord SE 4. Just recently it began to auto lock the back doors at every stop. It's normal to do this once at startup. But now it's every stop and start. It's pretty annoying. I searched for an answer but can't seem to find any good hits. Has anyone ever heard of this issue and can you point me in a direction to troubleshoot? Thanks in advance!

Accordian47

As I'm sure you know, the locking of the doors automatically is an intended feature, the car locks the doors when the car is placed in drive and it reaches a certain speed. There is supposedly two different types of power lock systems on the 2003-2012 Accords, one of which is the basic system and one is a type that is incorporated into the alarm system. The second is more complicated but in either case you should look for four main causes. (1): There maybe be an internal electrical problem in the power lock control unit, this can be difficult to diagnose as its a complex electrical control computer but it can be done with a multi-meter and some testing of the various inputs and outputs. (2): There may be a damaged wire in one of your door harnesses (the wiring harness that goes from the interior/body of the car, out into your doors, it looks like a ribbed rubber hose in the door jam when the door is opened), if there is a short in one of the wires leading to a lock switch or to one of the lock actuators this could send false information to be sent to the control unit or damage the control unit. (3): You may have a problem with one of your sensors on the automatic transmission that tells vehicle speed or the associated wiring between the sensor and the ecu as well as the wiring that is used by the ecu to share vehicle speed information with various other control units. (4) There could also be a problem with the shifter (if automatic transmission equipped), the automatic shifter has switches on it to inform various other control units and circuits as to the position of the shifter, if for example the switch or wiring for the "Park" or "Drive" positions becomes damaged, you could get inconsistent information being sent to the power lock control module, something like a loose wire could cause intermittent signals of which position the shifter is currently in causing it to lock and unlock the doors.

My guess is #3 or #4, The transmission sensor that is referenced for vehicle speed, is used by the control computer to operate the speedometer and by various control units. What is likely happening is that the power lock control module is getting an inconsistent signal as to what the current vehicle speed is or what position the automatic shifter is currently in. These two problems would be my main guess.