2007 Honda Accord - Power Door Lock Cycling
I was called out today to look at a 2007 Honda Accord EX 4DR with the complaint of Door Locks that cycle. The exact customer's complaint is, if the key is in the Ignition, and the Driver's Door is opened and then shut, all the Door Locks will attempt to Unlock twice, and then Lock. This whole process happens in less than 5 seconds.
It does not matter Ignition Switch position, as it will do it key off or even with the engine running. Just the key has to be in the Ignition. Any of the other doors can be opened and closed and nothing happens, only the Driver's Door causes this. I looked at data using the scan tool, and all Door Ajar Switches, Lock Knob Switches,& Lock/Unlock Switch Inputs appear to be reading correctly.
This is at a used car lot and the vehicle is from the auction, so unfortunately they have no history on how/when this problem came about.
They have tried several parts before we were called out, including the Multiplex Control Unit (MICU) and the Driver's Door Master Switch, which includes the Door Multiplex Control Unit. One thing they did show me that was interesting is, if the Driver's Door Master Switch is unplugged and the Driver's Door is open and closed, all the Door Locks will attempt to Unlock twice, but not lock. They verified this on another 2007 Honda Accord on their lot. I assume since it did it on both, this must be a normal operating strategy for this vehicle when the switch is unplugged.
So my question would be, is my "Unlock twice and then Lock" situation some type of normal operating strategy when the MICU sees something that it does not like? Has anyone ever seen this problem?
Thanks for your time and I would appreciate any help.
I just want to take a moment to congratulate you on your post. This was very well written and detailed enough for someone that is familiar with the door lock fault strategy on this vehicle to understand the concern and offer assistance and advice if they can.
I believe that you're right in your assumption that the symptom is caused by an input that the multiplex door module is not satisfied with. I'd be willing to bet that there's a problem with a door lock actuator. I know that certain generation Honda's would cycle the actuators if there was one that wasn't fully locking or unlocking.
Hey Brin. Thanks for the reply. I am heading back out this afternoon to look at this vehicle again. I will make sure to test all the Door Lock Actuators. I will keep you posted on what I find.
Does the other car on the lot do the same thing as the complaint car? I wonder what normal situation you would have the key in, then open and close the door. That peaks my interest a little. I don't have an answer, just spitballing here...
See my post below about what fixed this vehicle.
I went back out yesterday and thankfully found the problem on this vehicle.
It turns out, if the MICU sees an open on the Driver's Door Lock Knob switch, it will cause this door lock cycling, when the Driver's Door is opened and closed. This Driver's Door Lock Knob Switch is internal to the Driver's Door Lock Actuator. We found that this switch had not failed completely, but rather would get "stuck" between the Lock and Unlock states and cause this issue. If you manually moved the Door Lock Knob up and down, this switch would read correctly.
Thanks to those that replied here and sent me an email or message directly. Apparently others have ran into this same problem as well. Hopefully this post will help someone else in the future.