Toyota Nation Forum banner

1 - 20 of 33 Posts

·
Registered
Joined
·
16 Posts
Discussion Starter #1
Hey, just wanted to ask if anyone knows if there is a relay for the high beam headlights on my 2010 highlander. They just stopped working the other day. I don't use them that much but wanted to try to get them working again. I have checked both fuses, under the hood, for the left and right high beams and they are good. I have taken both bulbs out and checked the filament and they are both good as well. When i push out the switch (turn signal lever) inside the car to activate the high beams the notice on the dash comes on that says they are on but they are not. I jumpered a wire from the positive side of the battery to the fuse on the high beams and they turn on and work fine (don't know if that is bad for the car or not). I have checked for voltage at the fuse box and the bulb connectors on the high beam side and there is nothing, only on the low beam side. This is the only function on the turn signal switch that is not operating correctly. I didn't know if there was a relay for the high beams or how i can tell if it's the turn signal switch on the column? I did take the covers off the steering column and i didn't see any lose wires or anything. Any suggestions would be greatly appreciated.
 

·
Registered
Joined
·
3,984 Posts
Basically you went from step one of knowing the issue to step three of testing the issue. Step two is troubleshooting the issue. The wiring diagram will show the connectors, fuses, relays, switches, and other components to test.
 

·
Registered
Joined
·
16 Posts
Discussion Starter #5
Basically you went from step one of knowing the issue to step three of testing the issue. Step two is troubleshooting the issue. The wiring diagram will show the connectors, fuses, relays, switches, and other components to test.
I'm just not sure where to look for a wiring diagram to see if there is a relay for the high beams or how to test the turn signal switch to make sure it's working properly. I was really really hoping there was a relay that i could switch with the low beam headlights or something.
 

·
Registered
Joined
·
3,984 Posts
I'm just not sure where to look for a wiring diagram to see if there is a relay for the high beams or how to test the turn signal switch to make sure it's working properly. I was really really hoping there was a relay that i could switch with the low beam headlights or something.
Wiring diagram would tell you that. Up to you to either get a wiring diagram, using Toyota TIS and getting your two days, or making do without it. If you get a wiring diagram, I may be welling to trace it for you. Problem could be anything, could be so simple we don't actually need a diagram or more annoying that we have a lot of diagnostics to do. I sure don't know what is wrong with it without being there or not having a wiring diagram. Someone else might be willing to chime in on better assisting you.

If anything, just check your basics again and make sure everything is hooked up. Do a google search and maybe you will get lucky on finding a wiring diagram.
 

·
Registered
Joined
·
16 Posts
Discussion Starter #7
Wiring diagram would tell you that. Up to you to either get a wiring diagram, using Toyota TIS and getting your two days, or making do without it. If you get a wiring diagram, I may be welling to trace it for you. Problem could be anything, could be so simple we don't actually need a diagram or more annoying that we have a lot of diagnostics to do. I sure don't know what is wrong with it without being there or not having a wiring diagram. Someone else might be willing to chime in on better assisting you.

If anything, just check your basics again and make sure everything is hooked up. Do a google search and maybe you will get lucky on finding a wiring diagram.
Sounds good. I will try to google those wiring diagrams and maybe someone on here has has this same problem before and knows what to look for. Thanks so much for your help Vangm25.
 

·
Registered
Joined
·
3,984 Posts
This is what I would test for:
  1. Test for power from the high beam connector
  2. Test for power from the high beam fuses
  3. Test for power from the relay highlighted in yellow
  4. Test for power from connector 2G pin 1
  5. Test for power from connector 2D pin 8 and/or 9, which ever one or both is connected.
Options to consider:
  1. Swap low beam relay(s) with other identical relay's
My assumption is that connector 2D pin 8 is the high beam wire as DRLs are typically high beams. My assumption is also that the ground wire is connected as you said that you got the high beams working by directly connecting the battery to the fuse. The circuit is relatively simple like I said before, I just don't get how the H-LP (HI) Relay works. I also sorta doubt you would need to go pass the ECU but don't take my word for it. Good luck!
 

·
Registered
Joined
·
16 Posts
Discussion Starter #15
Ok, thanks guys. I'm going to do some more testing and try to find that hi beam relay that is in the wiring diagram. I was unable to find it today during my searching.
 

·
Resident Nutcase
Joined
·
12,146 Posts
Guys, please check your years. All the wire diagrams posted so far are 2011+ with separate high and low beam bulbs. 08-10 uses a different architecture for switching the H4 bulb. There was some confusion about the 2011 diagrams above though, just know they use a mosfet (see below) to control the DRL on the high beams. The mosfet can act like a relay or do PWM (pulse width modulation) to run the bulb at 40% for DRL. The 08-10's do the exact same DRL strategy for the low beams.

Unfortunately this is not going to be an easy replace a relay kind of fix. If you have DRL's (and most 08-10's do), there are NO relays for low and high beam on the 08-10 highlander. That symbol is a mosfet (semiconductor...basically a big transistor/solid state relay) See attached wire diagram. Basically in blue is what you did when you connected 12V to the fuse, you bypassed the mosfet and backfed the other bulb through the parallel circuit.

If these have failed, you will be replacing the entire engine compartment junction block as the mosfets are not user serviceable parts (this is why I built a relay harness to protect the mosfets when I put in high power HIDs).

To get to the connectors your going to need to remove the fuse block from the car and partially demo it. I've never done it so can't give any advice there, sorry.
But:
-You know the bulbs work once your put 12V to the fuse, so everything downstream of the fuse is good.
-You know the ECU is good because the combination meter (edit: sorry old habit, that's the gauge cluster) is showing the high beam symbol.
-You need to check the connection between the ECU and the engine compartment junction block and make sure its getting the right signals from the ECU.
-----in the wiring block pic, I circled a wire and wrote a 1. That is the high beam control wire. That wire should be 12V to ground when the high beams are OFF and GND when the high beams are ON.
-----in the wiring block pic, I circled a wire and wrote a 2. That is the headlight (lowbeam) control wire. That wire should be 12V to ground when the low beams are OFF and GND when the low beams are ON.


If your inputs are good, and your output is good when bypassing and powering a fuse, that leaves you with only 1 option, the mosfet has failed and needs replacement.
 

Attachments

·
Registered
Joined
·
16 Posts
Discussion Starter #17
Wow, thanks everyone and sweeneyp for the detailed replies. I'm going to have to look at this in the morning with a fresh head and do some testing. This is definitely maximizing out my troubleshooting skills. Haha. Thank you again for taking your time out of your day to help.
 

·
Registered
Joined
·
55 Posts
It would be helpful if posters would put some demographics on the year, and trim level of their highlander, as well as overall area they live in...
 
1 - 20 of 33 Posts
About this Discussion
32 Replies
7 Participants
biker5500
Toyota Nation Forum
ToyotaNation Forum is a community dedicated to all Toyota models. Come discuss the Camry, Tacoma, Highlander, 4Runner, Rav4 and more!
Full Forum Listing
Top