Yaris 2007 remote entry doesn't open (it only closes)

[nicorac]

Hello everyone, I'm experiencing a strange issue with my Yaris 2007 remote entry control; maybe someone could share some light on it.
Sorry for my bad "technical" english (hope I'm using the right terms).

The issue is this: on the remote entry control only the Lock button works, Unlock does nothing.

Details:

• Yaris 2007
• one key with 2 buttons embedded remote (Lock/Unlock) + transponder
• another key with transponder only (no buttons at all)

Tests I've done:

• all the doors Lock/Unlock using the internal switch (the one on driver door panel), so I exclude fuse or cabling problems
• all the doors Lock/Unlock using the mechanical key (outside the driver door)
• all the doors Lock by pressing the remote Lock button (even far away from the car) and the red LED on the key lights up, so I exclude remote battery problem and radio issues
• pressing remote Unlock button does nothing (I hear no noise at all) BUT the red LED on the key lights up, so I exclude the button itself is broken

I tried to re-add the remote following the procedure here (http://www.yarisworld.com/forums/showthread.php?t=20865), but nothing changed.
To confirm I followed the steps correctly I also tried to remove all registered remotes; after that the remote was fully nonfunctional.
Then I re-added it, but I still have the same issue: Lock button works but Unlock not (LED key lights up with both buttons).

Hope someone could help me, I'm getting crazy

[Lil Abner]

Well, before you go too crazy, and before other people post, maybe try cleaning the buttons first? I know you said the light comes on, but that doesn't mean anything. I'd say pop the remote apart and clean the contacts just to be safe. It wouldn't hurt, and will only take a few minutes. Plus it's probably dirty after all these years.

[Revsson]

I would add that even though the LED lights, doesn't necessarily mean that the battery
is still good. As suggested, why not take it apart and clean it. Check the battery
voltage or even replace it. That way, you know you are probably starting with a like
new remote. CTScott can verify, but LEDs only need about 0.7v to light. I believe
the battery in the remote is a 3.0v. So, if it is indeed the original battery from 2007,
it might be time to change it anyway.

[nicorac]

Thank you both for your replies

Originally Posted by Lil Abner

maybe try cleaning the buttons first?

I'll try ASAP, but I don't think this could be a solution.
Button should be a single contact one, so if the LED lights up it means the contact is closed...
But maybe the button is a double contact, one for the power/LED and the other for the command; I'll check it this evening.

Originally Posted by Revsson

I would add that even though the LED lights, doesn't necessarily mean that the battery is still good.

The remote surely has a single radio circuit that transmits two different codes on the same frequency, one for Lock and another for Unlock command.
Lock ALWAYS works, even far from the car, no one single command missed.
Unlock NEVER works, even near to the car.
That's why I excluded a battery issue.
Anyway it worths a try...

[CTScott]

With the way that the remotes work, the lights wouldn't light up unless the microcontroller saw the switch input, so I don't think it's a contact issue, and since it works for lock, I don't think it is battery either.

The "Door Control Receiver" receives the wireless signal from the remote and then sends the lock or unlock command to the "Main Body ECU" via LIN Bus. So, the main body ECU is the one who should be doing the work. The switch on the door is an input to the Main Body ECU, so since it works with the switch, it seems that the main body ECU is OK.

So, without either connecting the Toyota TechStream system to the car to diagnose if the command from the remote is coming through, or having some parts to swap (a remote and a Door Control Receiver) it is difficult to determine where the problem is.

[nicorac]

I've made a little step forward.

I measured the cell battery: 2.9v (ok, with no charge attached, anyway...)
I tried cleaning the button with contact cleaner: no way.

Then a lucky break: pressing the Unlock button twice really quick it worked, all of the times.
When I say really quick I mean really quick, say 2 presses in less than 0.3 seconds.

It seems some kind of security feature

[CTScott]

Originally Posted by nicorac

I've made a little step forward.

I measured the cell battery: 2.9v (ok, with no charge attached, anyway...)
I tried cleaning the button with contact cleaner: no way.

Then a lucky break: pressing the Unlock button twice really quick it worked, all of the times.
When I say really quick I mean really quick, say 2 presses in less than 0.3 seconds.

It seems some kind of security feature

That would make me suspicious of the remote itself. Did you clean both the circuit board side and the rubber membrane side of the switch?

[nicorac]

Originally Posted by CTScott

That would make me suspicious of the remote itself. Did you clean both the circuit board side and the rubber membrane side of the switch?

Sorry for the late reply.
Well, I used a spray cleaner (the one used in my electronic lab to deoxidate contacts), and I tried to put it deeply into the button.

Another thing that makes me think about a "software" issue is the following test.
I tried alternating a double-quick press to a single press, in a sequence like this:
XX--(3s pause)--X----XX----X----XX----X---- and so on.

The double clicks were all successful and all the single ones failed.
AFAIK a bad-contact issue should not be so regular, I expected that some of the single presses was successful, and/or some of the double ones fail.

I'll try to remove the remote battery and leave it unpowered for some time, then delete and re-register it. Who knows?