Gotta be a relay, right?
 

I bought my 2012 ES350 from a reputable local lot back in April and everything seemed fine until a couple of weeks ago. I managed to break an ear off the filter housing while changing the oil since their mechanic decided to put it on "real tight", and I found out some lug nuts were way too tight (no surprise there) when I replaced rotors and pads after developing pulsation during braking.

After the annoyances during the oil change and brake work, I figured I would check a few other things out since my wife is the primary driver and I don't usually get a chance to do so.

Other than a broken tab on a rear vent, the only problem I could find was that the high beams don't come on. Easy fix, right? Pulled the bulbs, they looked good and metered out just fine. I couldn't get my test probes to find a hot leg in either socket, so I moved on to the fuses. Using a 12 volt tester, I found out that neither fuse is getting any voltage to it. The car is running, the high beam switch is turned on and the blue high beam indicator in the dash is lit up. So, it's gotta be a relay... right? If so, where are they located? I poked around in the car and the internet and can't find the location for the relay that feeds the two high beam fuses.

Does your fuse box match this?
https://knigaproavto.ru/shemy/en/lex...x-diagram.html

The numbers assigned to the locations don't match, but the layouts and descriptions assigned to the locations do. For example, on the diagram you linked, the locations for the high beams are labeled as 32 and 33. My owners manual and decal inside the fuse box lid number those same locations as 29 and 30.

https://cimg1.ibsrv.net/gimg/www.clu...78f17ff5e8.jpg

maybe this is useful

Thanks for that file nevernu.

I expect that the fault checking procedure is the same for high beams as it is in the attachment, so my next step should be checking voltage at the instrument panel junction block. Since the diagnostic guide is for the low beams I'm not sure which terminal and/or wire harness position I need to test. Is there another illustration that covers the same diagnostic procedure, but for high beams?

sorry wrong pdf. try this one :)

Well, there are additional diagnostic steps for high beams. Kinda neat that power isn’t applied to the high beam terminals in the engine power block if a short is detected. Unfortunately(?) I don’t have a short, so it looks like I have to go digging in the interior power block.

I’m done for the day since high beams aren’t critical where I am. I’ll let you all know what I find when I resume.

Thanks to all for the help!

edit:
Just how deep in the dash is the Instrument Panel Junction Block Assembly mentioned in step 5? I think I found it looking up junction boxes... if I'm right I might be able to position my head next to the dead pedal and look up at it.

here are some locations

I was unable to find the instrument panel junction block (JB) assembly. I'm thinking it's closer to the instrument panel than I'm willing/able to go.

Since I had some extra time on my hands, I disconnected the positive battery terminal, removed power distributor from the engine JB, and took off the cover to see what I could see...

https://cimg3.ibsrv.net/gimg/www.clu...2942e4c7e9.jpg
So... A and B are where power enters the module through two connectors. C and D are where two more connectors attach to feed power to the fused components. Pins 1 and 2 feed the fuses for the high beams (labeled here as 1 and 2.) I was expecting the board to be sealed with a UV hardened clear plastic, but it is sticky and very soft.

I noticed that with the fuses in place, there is continuity between pins 1 and 2 with 0 ohms of resistance. Since they are separate pins and fuses I would expect them to be electrically isolated past their respective fuses. I'm wondering if the board inside the power distributor is damaged and it somehow caused a problem upstream at the instrument panel JB. While I did notice dark spots around some of the chips, they didn't appear to be thermal.

I had hopes that the disabling of the high beams was a volatile setting that might reset itself since the battery was disconnected for over 30 minutes. So, I removed the high beam fuses before reconnecting everything. Sadly, when I turned on the lights and hit the high beam switch there was still no voltage at the supply side of either the high beam fuses. So, my next step will be making an appointment with a service center.

Thanks for the help with this very small experiment!

The instrument panel J/B is on the left side of the steering wheel behind the storage compartment inside the dashboard. You need to squeeze the storage compartment container on both sides and swing it out of there to see the fuse box.

I found some testing procedures for the high beams that may help you. You also need a scan tool or a copy of Toyota Techstream software for the active test.

You can also go through the test of the high beam fuses and the dimmer switch without any scan tools. (found in the 2010 Lexus ES 350 - Headlight (HI-Beam) Circuit PDF)

It turns out there is no relay you can test, the relays are built into the Power Distributor which is built into the Engine J/B. Read through my attached PDFs for more information on how the system operates.


https://cimg5.ibsrv.net/gimg/www.clu...37495c526b.gif
https://cimg6.ibsrv.net/gimg/www.clu...4827532b91.png