Unlock Works / Lock Doesn't

I want to preface this by saying I have searched the forum on all topics related to this and haven't found a solution for the exact problem, so I'm not convinced it is the actuators.

I can unlock all the doors perfectly fine with the door switch or remote, however no doors will lock with the switch or the remote. When I press lock on the door switch, I can hear the relay activating under the dash but no doors lock. I first experienced this on about 3 occasions over the past couple months, but as of this past weekend, the lock function doesn't work at all. I checked the door lock fuse and it is fine.

Since the unlock feature works fine, and the lock feature doesn't work for any doors, it seems unlikely that all actuators failed at exactly the same time. Since I can hear the relay clicking when I press lock, it makes me think that the switch and relay are fine. Thoughts anyone?

2012 Tundra Crewmax - 5.7L with 165k miles.

 

Are all of your sensors for when the door is closed clean and working? I think there is a setting where it won’t lock with a door open. Maybe one of those sensors is stuck and the truck thinks the door is open.

 

I think the sensors are fine, since the door ajar light doesn't come on (I assume it is the same sensor?)

 

Try turning the key in the driver side door. All doors should lock. This will provide a little more data either way.

From what I can understand, the ECU actually sends the locking signal to all doors. Multiple input parameters have to be satisfied before that happens. The interior door-lock switch signal, or the door-closed switch, is each just one of those parameters. The interior door-lock switch is not directly wired to the door-lock motors.

 

Try resetting it he alarm. Do your door locks work when you press lock button on the driver side door??

 

When I turn the key in the driver side door, only the driver door locks (however I actually don't remember if it locked all doors before, as I haven't used the key for years).

 

I tried that and no change in results (I assume resetting procedure is turning the key on/off 3 times within 3 seconds?)

 

Using the key to lock the driver door locks all the doors.
Yes.

 

Your driver door is locking mechanically with the key. To short cut the questions, use the table below to diagnose. It's the top line of the chart. Since your doors are unlocking, I would suspect the Main Body ECU.

 

Thanks for sharing the table. It does appear that it is symptom 1, which would indicate Power Source Circuit / ECU. Any idea how to test these to narrow down the source of the problem?

 

My Celica had this issue, but along with the door locks other things weren't working either like my tail and license lights, stops, moon roof, fuel gauge interior lighting and others and it was the body ECU. I pulled one out of a wrecker at the yard and replaced mine and all my stuff came back.... So it may be your issue.. Maybe check everything else before you go down the ECU path...

 

As I said above, your doors unlocking indicates the power circuit to the Main Body ECU is fine. According to the chart, that leaves only the Main Body ECU as the possible issue. Before buying an expensive component, I would inspect and trouble-shoot the ECU harness for good connection, and insure that no "lock" signal is coming out of the Main Body ECU when you attempt to lock the doors.

The Main Body ECU is located high up in the driver-side kick panel/dash area, and appears to combined with the "driver side junction block". Be advised that the Main Body ECU is where the theft deterrent (immobilizer) system is monitored. If the Main Body ECU must be replaced, then you are looking at having to match the keys (chips) to the ECU.

 

Thanks for this. Question - If I hear an audible "click" under the dash when I press the Lock button, would that indicate that the "lock" signal is coming out of the Main Body ECU, or is that click related to a relay between the switch and the ECU?

 

Electrical is not my thing, but the wiring diagrams show no relay symbol in the Main Body ECU door locking circuit(s), unless Toyota has used another code to indicate fuse or relay.

If there is a relay, the only place it could be is in the combined "driver side junction block" (DD?). I agree that the clicking seems to indicate an ECU lock signal is being provided. If you find a door-lock relay, remove and apply 12V across the coil terminals while checking continuity across the contacts side. Assuming the relay is normally open (NO), you should have continuity (closed circuit) when the coil is energized. If energizing the coil makes no difference to continuity across the contacts, then the relay is your problem

Door unlock circuit connects to one or more terminals of the MB ECU. Door lock signal is from a separate terminal (ACT+).

It appears MB ECU Locking circuits to all door-lock motors are white wires up until a connector inside the door. There will be other white wires in the vicinity of the MB ECU, so take care to isolate the right wire.

 

I have a similar issue with my old '03 Camry. Passenger doors will not unlock when interior temps get hot. The drivers door works fine either way. I also hear a relay click when using the FOB or the button on the door but no go on the unlock. It's a common problem with the Driver side junction block. There are relays built in to the circuit board which malfunction depending on temps. Not saying this is your problem but just putting it out for info. Good luck.

 

Thanks for the suggestions. I'll see if I can figure out where the driver's side junction block is and check the connections on the MB ECU.

 

You should remove the battery ground cable, at least during your initial inspection. At some point, the ground cable may have to be reconnected to confirm no voltage on a specific identified wire or terminal (avoid if possible). If you short the wrong terminals, you could have some very expensive ($$$$) collateral damage if the battery is connected.

Another option is to have a professional check out your problem, and let him take the risk.