Turn Signal "Clicker"

if you can't hear the flasher clicking, it may be time to get your hearing tested. It happened to me.

 

If you don't know: Most "clickers" are the actual component which causes the lights to flash.

The clicker starts in the on position when power is not applied. The switching part is a strip of two dissimilar metals sandwiched together. When power is applied, the two metals heat up at different rates, thereby causing the metal strip to bend due to differing rates of thermal expansion. The bending causes the strip to break contact, thereby stopping the flow of electricity - causing the turn signal light to go out - and also causing the bi-metal strip to cool and fall back to the original starting position . . . thereby making contact and causing the cycle to start again.

You can't just replace a "clicker" with a "chime" unless it is designed to replace the function of the clicker.

I increased the volume of a clicker for a high school girlfriend's parents by cutting off the top of the plastic cover and sealing it with a piece of cellophane and tape. It was loud!

 

The Prius is the only car that I have driven that places the turn signal indicators so close to the normal line-of-sight that the blink is noticed even though I am not really looking at them. Having had a hearing problem for many years I almost never can hear the clicker over road noise no matter what the car. The attention getting, near line-of-sight blink is another plus for the instrument display on the prius.

 

<div class='quotetop'>QUOTE(Sufferin' Prius Envy @ Nov 21 2007, 10:12 PM) [snapback]542760[/snapback]</div>

Yes, the clicker is what's making the light flash. But the thermal method of making the circuit flash you describe went out of use in the 1990s in American cars and I'm not sure the Japanese ever used them. Modern stuff just uses a relay with just enough electronics in it to make it cycle open and closed at a pre-determined rate. The thermal flashers didn't give very much control over flash rates, took a fair amount of juice, and were too quiet. If you think about the cars of the 60s, 70s, and 80s, you may not have had any flasher sound at all to speak of, and the flashers often flashed too slowly to be very useful when turn signals were sharing a bulb with the brake lights. The newer relay-type flashers click more clearly and distinctly, are more reliable and heavy-duty, and can have a factory-set flash rate that won't vary with temperature or the load on the circuit like the old ones would.

It used to be that flashers were a fairly standard part, like fuses; there were only a few shapes and setups and they were a plug-in deal to replace when failed or if you wanted to get different properties (heavy duty for towing, louder, etc.) In older American cars the flasher was just an little metal can plugged into a round socket in the fuse block, and if you wanted a new one you just unplugged the old one and plugged in a new one. More and more they are deeply integrated into the vehicle systems, nonstandardized, and can't be altered. I don't know where the flasher is in the Prius or if it's still a standard part or not. Turn on the signal and look around under the dash to see if you can locate the source of the clicking (this may take a buddy with better hearing?).

Now I have to bring up one exception to all that rule. My last car was a Ford Focus, which apparently used a solid state relay for a flasher, with electronics driven by a quartz crystal that was shared with a number of other vehicle functions that required any form of time keeping. It would have made no sound whatsoever, so Ford actually made the same speaker that says "Bong, bong, bong" also say "tick tock, tick tock" at appropriate times. Focus owners sometimes intentionally killed the speaker to make the signals go silent (albeit at the loss of "bong, bong"). In the later model Focus (after 2002 or 2003 I think) they cranked up the "tick, tock" VERY loud. It's also odd-sounding, like the percussionist has moved in under your dashboard and is playing with some wooden sticks,. Funny how we all got used to them making the exact same sound and when one vehicle's flasher sounds different, it's rather a surprise.

 

The rest of your post is very interesting info. The two dissimilar metals sandwiched together I've definitely seen on my dad's former (piece of crap) 1980 Chevy Chevette.

I've had a number of rental Ford Focuses (I think somewhere between 02-04 model years) and the funny thing is that their turn signal flasher sounds IDENTICAL to that of my Nissan 350Z and the 02-04 Nissan Altimas I've driven. I figure they might all use the same part.

 

The Prius "clicker" is located just above the instrument panel fuse block -- you may need to remove the lower trim panel to get to it.

As far as I can tell, it's a regular mechanical relay. It's used for both the turn signals and hazard flashers.

IG = ignition switched positive
B+ = always on positive
GND = ground (negative)
EHW = hazard lights switch (to ground)
EL = left turn switch (to ground)
ER = right turn switch (to ground)
LL = left turn light
LR = right turn light