Car not sensing keyless remots

[xsnrg]

Our Avalon Ltd suddenly no longer senses the keyless remotes. I even tried a new battery in each of them. All sensors seem to be 'offline' ... interior, trunk, doors. Could it be a fuse? Or likely some other part in the sensor system? Thank You!

[inov8]

Do the Smartkeys still allow you to start the engine? How about the exterior trunk opening button?

Here are some paragraphs copied from the '05 shop manual that might have some relevance:

Key Battery and Vehicle Battery Saving Function
In the smart key system, if the key is constantly located within the vehicle exterior actuation area of the doors the system maintains periodic communication with the key. Therefore, if the vehicle remains parked in that state for a long time, the key battery and the vehicle battery could be drained.
For this reason, if this state continues longer than 10 minutes, the smart key system automatically becomes deactivated.

BODY ELECTRICAL — SMART KEY SYSTEM BE-131 - Key Cancel Function

Key cancel is operated when certain operations are performed with the vehicle in the following conditions.
(1) Power source is OFF.
(2) Driver door is closed.
(3) Driver door is unlocked.
The operation procedures are as follows.
1) Unlock once with the UNLOCK button of the key.
2) Open the driver door within five seconds.
3) Unlock twice with the UNLOCK button of the key within five seconds.
4) Repeat open - close twice for the driver door within 30 seconds, and open again.
(Driver Door: Open - Close - Open - Close - Open)
5) Unlock twice with the UNLOCK button of the key within five seconds.
6) Repeat open - close once for the driver door within 30 seconds, and open again.
(Driver Door: Open - Close - Open)
7) Close the driver door within five seconds.
When key cancel is activated, the wireless door lock buzzer sounds once.
To return to the original condition, perform the procedures again. When key cancel is returned, the wireless door lock buzzer sounds twice.

[xsnrg]

The car only starts when you hold the Toyota logo on the fob right against the Start button, as if the battery in the remote is dead. I know the battery in the remote is not dead because (1) both remotes stopped working at the same time (what are the odd's?), and (2) I put a brand new battery in and still no response from the car. The door antennas, trunk antennas, and even the 'interior' antenna all seem to be not receiving anything from the remotes. It is acting although both remotes batteries are totally dead, but since I know that is not the case, I was thinking it could be a blown fuse or component of the system that 'receives' the signals the fobs put out. I would not be able to follow the steps above because step number 1 is not possible since the car is not sensing or responding to the presence or any signals being sent from the fobs. Your post does have me curious what 'power source is off' means and what 'key cancel' is ... does that essentially mean that smart operation is disabled/enabled using that procedure?

[Zembonez]

Are you able to take these remotes apart? I know on other vehicles I have been able to take them apart and clean the carbon terminals in the little rubber button inserts and the contacts on the tiny circuit board with a pencil eraser and revive them. Worth a look!

[inov8]

I agree the probability of both Smartkeys failing or depleting their batteries simultaneously is (no pun intended) remote. There is a fuse that seems to only protect the Smartkey ECU. It is marked "IMMOBI" and is 7.5A. It's worth a try to replace it and see what happens.

The first repair manual reference simply means if you leave or store a Smartkey either within the vehicle, or somwhere within range of the antennas (possible with an attached garage, I have found), the Smartkey system will shutdown after 10 minutes to conserve both the Smartkey and vehicle battery energy.

I posted the second reference only because a poster on another Avalon forum apparently experienced a Smartkey system disable after he allowed his grandkids to play with the lock and window controls, and remote. The objective of their game was to see if the one on the inside could stop the one on the outside from entering the car with a remote.

[xsnrg]

LoL... leave it to kids to happen upon a random sequence. I'll check the fuse tonight and if that doesn't do it,I'll probably have to take it to the dealer.

[xsnrg]

I swapped fuses with S-Horn (also a 7.5A) and no change. I guess it's off to the dealer to see what's up unless anyone has other ideas?

[inov8]

It was admittedly a long shot, but at least an easy test.

When I look at the factory diagrams, I am bothered that the transponder processing electronics (the ones that allow you to start the car with a dead remote battery) seem to be in the same module as those used for a "normal" start with the Smartkey anywhere in the car. If that module were defective, I would expect neither function to work. There is a tuner located in the rear right pillar ("sail" panel area) that receives smartkey signals. Has anyone recently done any repairs in that area? The tuner seems not to have a separate fuse, but is powered through the smartkey control module.

Perhaps we were too quick to discount the possibility of both remotes failing at virtually the same time. The batteries in our 2 remotes failed within days of each other, even though one is used 5X as often as the other. If the new batterys wre inadvertendly installed upside down (not sure if that is even possible), or the battery holder failed to make good connection, then both remotes would not work after the battery swap. Do you have a volmeter you can use to check the battery voltage? I think the + end (the outer case) should be "up".