Any Toyota guys around here ??

[rphillips]

Wife's 2010 RAV4, headlights on LO beam all is good, move stalk to HI or flash position and nothing changes, still LO beam only. A buddy told me last night, when in HI or flash position, both the LO and HI beams should be on. I've always thought when you switch to HI beam, the LO beam goes off. If my buddy is correct, and LO stays on, if 1 HI goes out, my wife may not notice, both will need to not work before she may see the difference. Anyone know "for sure" on a 2010 Toyota RAV4, if when on HI beam, both the HI and LO should be on?... That'd be great, though a pain to change, if problem is just both HI beam bulbs are shot.

[zed1015]

Normally when switching to high the low beam circuit is switched off and vice versa.
Only on flash does the low beam remain live while the high beam is "flashed" .
Whatever way the hi/lo on the RAV is configured the lack of high or flash still means there is a fault in the high beam circuit, switch, associated fuse or (unlikely) both high beam bulbs or filaments.

[rphillips]

That's what I's thinking, but on ours when switch to HI, the LO is not going off, What ours is now doing, whether switch (stalk) on LO, HI, or flash position, the LO's are on remaining on and looking good, but the HI's (which are also the DRL's don't do a thing. Is there possibly something that turns the LO's on if both the HI's were to go out. I just hate to dig in to the aggravating HI bulbs if that ain't the problem.

[zed1015]

It's very unlikely or a massive coincidence if both hi bulbs fail.
It's more likely a power feed issue in that circuit.
I'd start with the fuses.
As for whether the Lo's stay on when switched to hi i'd be asking on a RAV forum for the quickest answer if there's nothing in the manual..
Toyota RAV4 Forums (rav4world.com)

[rphillips]

Thanks, Should have said, I've checked the 4 fuses and 2 relays, they're good. Odd for both HI bulbs to go at the same time, yes, but if LO are on with the HI, one may not notice if just one HI went out, switching from LO to HI you would notice the lights get brighter just not realize not bright enough. Then when the other HI went out you would notice no change when going from LO to HI. Just got a response from RAV4 World, I joined earlier, a guy said the LO's go off when HI's come on, shoot not what I wanted to hear. Now wondering, in this new safety responsible world, if there may be a built in safety that turns the LO on if for any reason the HI's go off, Just to keep you from being in the dark if HI's fail???... Little more info., with wife's help, I raised hood to listen, when she initially turned lights on, substantial click from fuse box, probably the relay, when switching from Lo to HI, or HI to LO, a faint click from fuse box, not near as loud as when turning lights on. Thinking that faint click is telling me the switch in steering column is probably functioning. I guess next is to get in there and see if I can get to the HI beam bulbs....

[zed1015]

. Little more info., with wife's help, I raised hood to listen, when she initially turned lights on, substantial click from fuse box, probably the relay, when switching from Lo to HI, or HI to LO, a faint click from fuse box, not near as loud as when turning lights on. Thinking that faint click is telling me the switch in steering column is probably functioning. I guess next is to get in there and see if I can get to the HI beam bulbs....

Sounds like power to the relay but possibly faulty or sticking contacts in it.
It's possible that there's a failsafe sensor as you say in case the hi fails but i've never had a vehicle with that feature.
Most fuse/relay box's use the same type relays on multiple circuits so i'd be swapping out one from a known functioning circuit such as the lo into the high and see if that is the cause before digging deeper.
It may be just a new relay needed.

[Cipher]

Thanks, Should have said, I've checked the 4 fuses and 2 relays, they're good. Odd for both HI bulbs to go at the same time, yes, but if LO are on with the HI, one may not notice if just one HI went out, switching from LO to HI you would notice the lights get brighter just not realize not bright enough. Then when the other HI went out you would notice no change when going from LO to HI. Just got a response from RAV4 World, I joined earlier, a guy said the LO's go off when HI's come on, shoot not what I wanted to hear. Now wondering, in this new safety responsible world, if there may be a built in safety that turns the LO on if for any reason the HI's go off, Just to keep you from being in the dark if HI's fail???... Little more info., with wife's help, I raised hood to listen, when she initially turned lights on, substantial click from fuse box, probably the relay, when switching from Lo to HI, or HI to LO, a faint click from fuse box, not near as loud as when turning lights on. Thinking that faint click is telling me the switch in steering column is probably functioning. I guess next is to get in there and see if I can get to the HI beam bulbs....

Did you pull the bulbs and check? DRL ages bulbs. I was driving far from home last year and as an optical sensor switches from DRL to headlight mode I slowly realized both low bulbs were dead.
High uses all four bulbs and low the two lower wattage bulbs. It got darker and man folks are hateful pricks when their sense of justice is upset by what seems to be a person failing to dim their lights. Many of the most upset were sporting HID dazzle bulbs. You could smell the hatred.

This was a Chev but you may have a similar setup in a Toyota.
I know Ill never flash an oncoming car again.

[rphillips]

I checked the fuses and relays by swapping with known good ones. I've learned, on my RAV4, the DRL is the same bulb and same filament as the HI beam, DRL is operated by less current to bulb's filament, then full current to same bulb and filament for HI beam. No doubt, these DRL's running for 13 yrs., as both of these bulbs are the orig. are due to be bad. Learning how they work makes me lean toward both bulbs may be shot but still not sure about the LO being on in either HI or flash position. My thinking, there's got to be 2 different circuits to the HI bulbs, one with lo current for DRL and another source for HI beam, both those sources going bad seems odd, though could be wire from source of current to bulb. I dun'no, next will be trying to get the bulbs out and find if there's current getting to them... on a warmer day, I'll dig deeper.

[Who Dat?]

The way Toyota DRLs work is that they have a few relays that switch the power and ground paths to/from the high beam bulbs.

For normal high beams, power feeds both bulbs and continues to ground.

For DRL, power is fed to one high beam, then a relay interrupts the ground wire and directs the current to a relay above the other high beam. Power then goes through the second bulb and on to ground. Doing this, each bulb gets half the voltage. Power goes with the square of the voltage change, so half the voltage results in 1/4 of the power, resulting in a dimmer light.

Check the DRL relays and the wire between them.

[rphillips]

thanks ya'll, It warmed up, a little, today, and back to the headlights. After removing the radiator support cover and radiator overflow tank, to gain access to the headlights bulbs, I installed new Hi beam bulbs and all is good. I made it a point to check after repairs, the Lo beams "do" stay on whether on Lo, Hi, of Flash position, I'd have never of thought it.... A great day for me, the wife is happy.

[Cipher]

thanks ya'll, It warmed up, a little, today, and back to the headlights. After removing the radiator support cover and radiator overflow tank, to gain access to the headlights bulbs, I installed new Hi beam bulbs and all is good. I made it a point to check after repairs, the Lo beams "do" stay on whether on Lo, Hi, of Flash position, I'd have never of thought it.... A great day for me, the wife is happy.

Thats awesome. So same issue I had more or less. Toyota has a better setup than chevy. Loss of hi is inconvenient but both lo is pure hell.