[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

 

[John P]

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.

 

[12BlueX]

Surprisingly, it all four can be the actuators. I had to replace all four actuators for my 04 MDX over time.
If you're handy, you can just purchase the mabuchi motors and just replace the motor itself instead of purchasing the expensive assembly. Very cheap and an effective solution.

04 right rear door actuator diy

Hi everyone, today I did the RR door actuator, but only changed the motor (mabuchi FC280PC 22125 off ebay) The lock was working intermittently and I know it will fail soon. Steps: The first 6 steps are similar to removing the front doors with less screws and no mirror...

www.mdxers.org

 

[Jcbyam95]

I know it's and older thread but maybe somebody will see this. I have the same problem where only the hatch functions. I have a second mdx, parts car now. I made sure all lock actuators worked before I pulled them, went to install the first one on the driver's door, it works, intermittently. Like if I pull the fuse and put it back in, it works immediately, once, then won't work again for a while. I checked both fuses and replaced them just in case but it hasn't changed anything. Obviously it's getting power? Not sure what to look for next.

 

[habbyguy]

There's not too much else to check, but if you can get to the wires going to the actuator, it would be good to see if it's getting a good solid 12volts (this assumes your battery isn't very low, which of course can cause the problem you're seeing).

The actuators (including the hatch) are all in parallel, except for the driver's door. Both are driven from outputs from the "passenger's multiplex control unit", which could possibly be bad. But if your hatch is opening, it's my bet that the other three (non-driver's) actuators are cooked. Maybe even the driver's actuator got flaky since your parts car was parked?

 

[Jcbyam95]

There's not too much else to check, but if you can get to the wires going to the actuator, it would be good to see if it's getting a good solid 12volts (this assumes your battery isn't very low, which of course can cause the problem you're seeing).

The actuators (including the hatch) are all in parallel, except for the driver's door. Both are driven from outputs from the "passenger's multiplex control unit", which could possibly be bad. But if your hatch is opening, it's my bet that the other three (non-driver's) actuators are cooked. Maybe even the driver's actuator got flaky since your parts car was parked?

All the actuators were checked just before I removed them so that shouldn't be the problem. I have not checked voltage so I guess that will be the next thing I try. Thank you

 

[habbyguy]

If it helps, here is the wiring diagram...