[hotrod351]

just inherited a 2005 MDX and having door lock problems. the only lock that works off the fob or master lock switch on drivers door is the rear hatch. by the way, it only has 57,000 miles on it.

 

[forbin404]

All 4 doors won't unlock? And the hatch is the only one that works?

Sounds like a master wire was disconnected somewhere near the door control.
You are going to have to take off a door panel and put a multimeter to check.

 

[habbyguy]

Check out fuses #9 (driver's side fusebox) and #10 (passenger's side fusebox). There's a common "door multiplex control unit" that is common to the doors. And a bad ground can cause all kinds of mischief, too.

 

[hotrod351]

fuses check good, and yes its the rear hatch only that will lock and unlock.

 

[12BlueX]

I would check the driver door actuator first.

 

[hotrod351]

how hard is it to get to.

 

[habbyguy]

Here's the odd thing... I finally found the schematic for the door lock actuators, and the three passenger door actuators are wired in parallel to the hatch actuator. That means there's no reason that the hatch would be unlocking and all the other doors NOT unlocking unless all four door actuators are bad. I really can't imagine that being the case. It would seem likely that there's some sort of wiring fault on whatever wiring runs to the doors, but not the hatch. You're really going to need a service manual to chase that one down. Oddly, the driver's door lock is unlocked using a different circuit (since it unlocks separately with the first push of the key fob unlock button), so that would seem to rule out just a bad wire.

I guess the best approach would be to pull one of the door panels off, and start probing for what happens at the actuator when you hit the manual lock button. The only thing I can think of is that there may be something wrong with the output of the passenger's multiplex unit (apparently it's located with the fusebox on the passenger's kick panel fusebox). Maybe the output of the unit is low, but JUST enough to trip the hatch actuator but none of the door actuators. You won't know until you do some probing...

 

[hotrod351]

fun fun fun