This is my first attempt to fix an intermittent door locking problem commonly to occur on hot days or when using the fob several time in a row.

COMPLAINT: All doors and the trunk door stopped responding to the fob, but only on hot days!

Why?

Most have attributed this to a bad door lock motor. And other's have suggested that one bad motor can affect the whole system. So where do you start?

First, I would try something else. Try removing the the master console arm set of switches (for windows and door locks) in the driver's door panel; and then undo the 2 electrical harnesses -- without removing the door panel. Just pop-up the group of window and door lock master switches and clean the contacts of just the door lock master switch. Easy!

* Use electrical contact cleaner as best you can to clean the switch contacts. And you may as a final step need to apply silicon if the switch plastic is affected by the cleaner and starts to stick after using the electric cleaner. TBD.

If you still find your fob is unresponsive on hot days, then you will need to proceed as follows to remove the door panel.

Remove The Door Cover/Panel

* Watch this video: https://www.youtube.com/watch?reload=9&v=MMRugjltUK8

* Just remove the 3 door screws as shown in the picture below,

* Unclip the wire harnesses, but do not remove the door locking actuator cables or mark them if you do.

Tip: Use a small screwdriver and squeeze it with one hand to depress the "tab" that locks the electrical connector in place.

FIX YOUR DOOR CATCH WHILE YOU HAVE THE DOOR PANEL OFF

* With the door panel hanging by the locking cables...

* Remove the three 10mm speaker screws, but not the speaker wire. Just let the magnet hold the speaker the the metal door frame...out of the way... while you reach in the speaker hole and remove the door catch. (3 bolts to remove first)

==> Then just spit the door catch assembly open by bending 4 tabs with channel locks. (Don't use a screwdriver and stab yourself!)

==> Then remove and flip the plastic parts over.

==> Then add two #8 flat washers to each side (total of 4 washers) which will act as shims... and that will put more pressure on the already worn plastic parts... hopefully making your door catch good as new! Reassemble. Easy-peasy!

IMPORTANT: Before you put the door cover on ==> initiate a "windows relearn" procedure as follows:

* Find and remove the quarter size (round) black tape cover which hides the relearn button. This cover and button is located about 8" from the speaker.

Why do this step?

1) It can't hurt and it may help both your window action and fix this door lock problem at the same time.

HOW? I hope the windows relearn might re-calibrate the BCM, but I really can't say for sure. I will know more over the course of the next couple weeks and if my intermittent fob/door lock/unlock problem is fixed. If is is fixed by doing this then I will say these measure are the cure for the problem. TBD.

CONCLUSIONS: If these steps don't work then your only other option is to either replace the entire Lock Actuator as a complete assembly, or you can take this assembly apart and just replace the locking motor inside. And if there is any truth to the possibly of one door like motor affecting all the doors, then I suppose I would replace the driver's side door lock motor first since it probably gets the most wear.



Good luck and let us know if any of these suggestions work for you!

More speculation and theory: Why can I open an lock all the doors the first time? And why when it is hot outside my fob doesn't seem to lock/lock the passenger doors, but reliably locks and unlocks the drivers door?

Well... To state what I can confirm on my car: My new to me 2004 FX45 driver's door lock works fine and is reliable. However, the passenger front door and the passenger side rear door locks are weak and I sometime have to lock my doors twice to fully lock the latch with moves 1/2 way with every button push on the door console or with the fob. Note: Unlocking seems to be fine, but locking seems to be a problem.

I also have reviewed listed in the above post and I'm convinced the repair should not be done as shown using a hard washer. Instead you should use a bi-metal, PTC-R device, which is commonly used by refrigeration motors to "close" the circuit with 4 ohms resistance, and which acts to "open the circuit" when the PTC-R exceeds 1000 ohms. I.e., this is normally closed resistor that "opens" when the PTC-R heats up to 1000 Ohms with tanks only split seconds. ...And this what you want to protect the circuit I'm guessing is controlled by the BCM. ...Which means this door actuator motor with a PTC-R inside works like a resetable fuse that protects the BCM!!! ...So don't short the motor contacts using a simple lock washer as shown in the video. ...But other than this I learned something watching the video.

What I recommend is to NOT use a metal washer, but instead order some PTC-R on Amazon. And this is what a PTC-R looks like after you remove it from your refrigeration device (housing you don't need). It's that "wafer" the size of a nickel.
Automotive lighting Rectangle Font Auto part Technology

So when faced with repairing your old motor, I think you can do so by removing the PTC-R from this home refrigeration device you can order on Amazon for less than $12 and when you take the PTC-R out and put it into your Infiniti door actuator motor... assuming the PTCR will fit... your motor should start working strong again. Note: It does not matter if the PTC-R is round or square. But it has to fit so the motor can be reassembled.

www.amazon.com
Amazon.com: Refrigerator Compressor Relay and Overload Kit 5 Sets,Refrigerator Starters QP2-4R7 4.7 Ohm 1 Pin Refrigerator PTC Starter Relays and 6750C-0005P Freezer Overload Protectors : Appliances
Amazon.com: Refrigerator Compressor Relay and Overload Kit 5 Sets,Refrigerator Starters QP2-4R7 4.7 Ohm 1 Pin Refrigerator PTC Starter Relays and 6750C-0005P Freezer Overload Protectors : Appliances
www.amazon.com

Alternatively, you might try this, now that you know where the problem lies. ...Try taking out the old PTC-R from your old door actuator motor -- and just clean the contact points and reinstall.

So long as you don't break the brittle wafer when you pull it out you may find all you needed to do was clean the build up of corrosion. I would also try to reposition the PTC-R so you new contact points!

Note: These PTC-R devices are bi-metal semiconductor, normally closed, switches that "opens the circuit" when it gets hot and then resets to "close" the circuit when it cools down.

Or you can buy the whole motor on Ebay for ~$13ea and that's a better bet if you ask me:

www.ebay.com
Car Door lock Actuator Motor for Infiniti Q60 Q70 Q50L QX70 FX45 S50 SUV FX35 | eBay
Car Door lock Motor for Infiniti Q60 Q70 Q50L QX50 QX60 QX70 FX45 S50 SUV FX35. For Opel Car door lock piece motor forInfiniti Q60 Q70 Q50L QX50 QX60 QX70 FX45 S50 SUV FX35 ,Car door locking device motor,280 DC car motor.
www.ebay.com

CONCLUSIONS:

I think the reason ALL THE PASSENGER doors are affected, are because every time you unlock and lock the passenger doors with 2 clicks on the fob, all these actuator motors get worn out the same. So that sort of dispels the idea one bad motor affects the other.

And I would say the reason why my driver's door works fine is because I bet the previous owner already replaced the driver's side actuator assembly at the dealer, because otherwise the driver's side door would go out first since it gets the most use with just 1 fob button push.

So more than any other fix as mentioned above, I suppose replacing the Master Window & Door Lock Switch panel in the driver's door might help, but everyone says it's the motor inside the door lock actuator(s) that is causing this intermittent lock and unlock problem that does seem to be temperature dependent, because that what a PTC-R does; I.e., it heats up and then opens the circuit... rendering the motor inoperative.

CONCERNS: I have read that when the door motors fail completely, you can't open the door manually or with a fob and you get locked in or locked out. ...And then you have to open your door by taking off the inside door panels WITH THE DOOR CLOSED and that does not look like fun according to this video:


Attachments

Quick update: I think you more #8 flat washers when fixing your door check. This will add more friction.

Here's an update on what to do:

I also found that if you close your door window and then use duct tape to hold the window in place, you can then remove all the screws to the inside metal door plate. and you can keep the 3 center window mechanism screws attached. You do this so you DO NOT have to remove the window.

Then you can pull the metal door plate away from the door frame. You can also remove the 3 screws that hold the door actuaator in place, which will allow you to pull the door actuator out to work on. Note: You don't need to remove the cable to the outside door handle.

With the door actuator exposed, you begin by cutting the plastic numbs that hold the door actuator case together. You will then remove the pin as shown in this video and you can then split the case. Note: Don't worry about breaking off the door actuator plactic clamps. Later you reassemble the door actuator using duct tape.

https://www.youtube.com/watch?v=hIMFcGWZ5Ns

Now you can replace the motor inside the door actuator. Alternatively, you can keep you old motor and just replace the PTC-R if you order one of these on Amazon and remove the PTC-R for use in your door actuator. This said, I do not recommend you follow the video above where they say you can remove the PTC-R (Thermosistor) and replace it with a split-washer. This is not good since it "closes" the circuit and MAY put stress on your BCM. I.e., the purpose of the PTC-R is to "open" the circuit when it there is too much stress on the system. And by "stress" I mean resistance or heat. Consequently, the PTC-R (Tharmistor) acts as a resettable fuse, which is what you want.

Anyway, pull the pin to split the door actuator. Replace the motor if you have one or just replace your old motor PTC-R with a new one you cannibalize from a refrigerator PTC-R part and you should be good to go. Alternatively, you can replace the door actuator for a lot more $$$.

Note: Don't worry about splitting the door actuator case and breaking off the nubs or the locking tabs. When you reassemble the "pin" and duct tape the enclosure you will be okay.

The job you have done is great, but it takes a lot of time. I'm just curious, have you spoken with a mechanic regarding your issue?
One easier solution could be to have locksmiths Rotherhithe check the car's electronic control module (ECM) and the door lock actuators to see if they are functioning properly. Additionally, it may be worth checking the car's battery and ensuring that it is fully charged, as a weak battery can also cause issues with the door locking system.

Noel: Are you a locksmith?

I fixed my door locking problem by cleaning my fuses nest to the emergency brake. However, I live in Hawaii where it's warm. I.e., cold climate owners report they fixed their dead battery (current draw problem) by replacing their AC-Amplifier. However, it's also evident all your door actuators motors (with PTC-R inside) can sink current to ground too. Fortunately, when your door actuator PTCR stops working, it will work again in 5-15 minutes. This is why your fob remote stops working after multiple open-close-open fob calls. I.e., those PTC-R can also remain closed and drain your battery down.

The easiest thing to do and the cheapest is to clean your fuses. The reduce the load on the BCM by disabling everything you can using your programmable options in your LCD display. I.e., turn off your auto seat relearn; and DLR, etc.

Note: One day I noticed my dome light would not work. It thought it was a burned out bulb, but it turned out to be the light switch sinking current to ground. And after I cleaned the switch, my dome light worked normally and I never had a dead battery in the morning.