key fob not detected

Does the car lock/unlock with the fob, either by having the fob on your person and touching the door handle or by pressing the lock/unlock button on the fob?

When you depress the clutch to start, the lamp in the start button should turn from orange to green (provided the fob is actually inside the vehicle). If the lamp stays orange, try holding a fob right next to the start button (as close as you can get it). Does the lamp then turn green? Will the car start then?

As far as I know, there's never been anything like a re-sync procedure with the Toyota keys. I've never had cause to find out anyway, but I'd do something like multiple lock button presses in an attempt to re-sync.

Short answer:

While it's not impossible that the UHF (see below) transmitter part of both keys has failed, it's probably unlikely.

It's highly likely that there's a problem with the UHF door locking receiver and/or with its connection to the certification ECU. The UHF receiver is located behind the trim between the C and D post, if I remember correctly. Think it's nearside - can't exactly remember without looking.

OR


The car UHF receiver is being blocked by a nearly radio source (possibly much high power than the key can produce) on the same or a close frequency. To attempt to check that, move the car a mile or so and try again. If it's this though, often getting the key as close as possible to the UHF receiver can sometimes unlock the car.


Long answer:

The system consists of the following (explanation over simplified):

There are two transmit and receive paths in the system. I'll call them LF and UHF. The LF part is a very short range path. In fact the LF part is more like a very weakly coupled transformer action rather than a "conventional" radio transmission. The LF part is very similar to the transponder "pill" system for security, often found in "conventional" keys.

The UHF part is a "standard" radio transmission. It's the path that's used when you press a button on the fob to lock/unlock the car. 

There are LF transmit antennas in the car door handles, one in the back of the central "cubby" box and one just behind the rear seat. The start button also contains an LF antenna, that's capable of both transmission and reception to/from the key fob.

As stated the car has one UHF receiver.

The key is capable of transmitting on UHF and receiving on LF. The LF part in the key also acts as a transponder "pill".


The "keyless" entry and internal key detection works like this:

You walk up to the car and pull the handle. Pulling the handle kicks the car into transmitting via the LF antenna in the door handle. If the key hears the correct LF transmission, it transmits back to the car on UHF. The UHF transmission is picked up by the UHF receiver in the car and the car unlocks.

Once in the car, the car sends transmissions on the internal LF antennas at regular intervals (pings the key). If the key hears those transmissions, it responds to the car on UHF. You can often see the led flashing on the key, as it responds to these "pings". This way, if the key responds on UHF, to a ping from the internal LF car antennas and the car hears the key on UHF, the car then "knows" the key is in the vehicle.

There will be similar "pings" when you attempt to start the vehicle and of course if the car hears no response on UHF at this point, you'll get "key not detected".

All the above is of course all dependant on a good-ish battery in the key. If you've a duff key battery, you're stuffed.  So there's a backup provided. The key also acts like a "conventional" transponder system. As I said the LF path is more like a transformer action, so you can transfer a small amount of data and power across it (enough to power a transponder), if the two "antennas" (the LF "antenna"/coil in the key and the antenna in the car start button) are very close to one another. This is what's happening when you place the key next to the start button. The key and car are communicating on LF only.

As the LF path works to start the car, but you can't unlock the car with the key, by just by pressing the fob button (i.e. not using "keyless"), then it's highly likely there's a problem on the UHF side. As both keys don't work it's likely the problem is in the UHF receive path.

OK, being pedantic, it will unlock if you put your fingers behind the handle without pulling. The Toyota system shouldn't be unlocking as you walk up to it. On owning 4 vehicles with the system, I've never encountered it doing that. Maybe a previous owner has ****ed with it.

Could the unlock button be being inadvertently pressed in your pocket?

Some vehicles (not Toyota, that I know about) in the distant past had badly designed keys where an electrostatic discharge from the person's clothing would cause the key to transmit and thus the vehicle to unlock. e.g. Nylon underwear!

Hi bolo1957 please have you an update about your snag?

been working away so havnt had chance to have it looked at , but was wondering if theres a fuse that governs the key fob funtion , any help or advice would be most appreciated

back on the case ,car has been standing for the last few months decided to try again , thought that because i had water ingress through the roof rails water might have got into the uhf reciever ,the trouble is i cant find it anywhere , any help would be most appreciated