Another problem with Automatic Headlight Leveling System

do a search for 'prius headlight sensor repair' the link should pop up with a .pdf instruction guide, i also downloaded it to my phone as it is easier to have your phone during the repair as opposed to a whole laptop under your car.

the sensor is attached b/t the frame and the drivers rear suspension, once you see the pdf file with detailed pictures and lift the drivers rear corner of your car it'll be impossible to miss. the detailed walkthough is for repairing your sensor with springs from a pen. There are 3 total on the sensor and I had 2 which needed replacement which worked out to 1 pen spring cut in half. I'm not sure if its due to cold weather or due to fact that steel pen springs are not as good a conductor as copper original ones, but after I made the repair I still had the warning light come on regularly for a week and periodically for a month but after that the warning triangle hasn't come back for a couple of months.

let me give you one piece of advice the pdf walkthough doesn't offer. Regarding the thin black arm that connects the sensor to the gray dog-bone-shaped arm, do not allow this arm to turn very far in either direction because the bolt that holds this black arm to the sensor is connected internally in the sensor to a piece of black plastic that will break on the 'tubes' holding the springs if you turn it too far either way.

The nice thing is you can remove it off the car, take it into your kitchen table where it is nice and warm to attempt the repair. If you take your headlight level sensor off and discover it is not the springs but that there is actual physical damage to the arms, you're gonna have to replace it. There is a guy on ebay selling new ones for $289 + $4 shipping, toyotapartszone.com sells it for $267 plus shipping, oem part #89408-47010. You can also buy them from junkyards but since this part is on the bottom of the car I recommend buying one from a southern junkyard so that they are not corroded already.

if you can do your own oil change you are skilled enough to replace the part. If you can do your own brake work then you are skilled enough to repair it if it is just corroded springs.

 

first step is to lift the corner and attempt the repair, if its not repairable you will have to buy a new or used one, once you have the one you plan on using back in, you should notice an immediate difference. I don't believe any calibration is necessary as I have read many many many posts on this issue and nobody has ever mentioned requiring adjustment as our HIDs are auto leveling.

i have 2 gen II prius and a corolla, I changed the sensor springs in one of them to make the warning triangle disappear but one of my arms is snapped so I need a new unit. Fortunately its in the car I don't drive at night in, but lets just say that the headlights are pointed DOWN DOWN DOWN!!! Compared to my other HID equipped Prius and my Corolla I can definitely tell the difference because at night I have to use hi beams in situations that I don't even need to use it in my Corolla with halogens.

I could be wrong, but I would be willing to bet that when the sensor is not operating properly it reverts to pointing them down to the lowest possible setting, and when a properly working sensor is in it works perfectly with no calibration required.

There is a junkyward that sells these parts periodically on ebay when he gets a few in stock and last month he had a HID leveling sensor from a mazda RX-8 which he claims was identical to ours, the only difference being the arms, so you would have to transfer the arms from your old unit to the new unit if you bought his.

 

So, like most here, I've had the display warning and the Scary Red Triangle, and also resent (refuse?) to pay upwards of $500 for a) a part that should cost considerably less, with a correspondingly smaller labor charge as well, and b) an obviously defective/poorly designed part which should have prompted a recall. Ranting aside, I've accepted the challenge and have crawled under the car and for the most part the removal seems doable; I have the 10mm wrench and can remove the two bolts and the two nuts. What I cannot seem to do--yet--is disconnect the electrical connection. I am somewhat tentative as I don't want to break or snap or tear anything that might up the final repair bill down the line. Any suggestions? pictures? (I have seen the pdf that shows replacing the coils in the sensor, but it does not share detail about disconnecting the electrical, nor show pics of this.)

I would almost consider opening up and checking, cleaning the sensor while attached, but I'm also thinking that if the sensor does need replacing, I will need to be able to disconnect in order to do so. For one more layer of complication, I also discovered that the part of the bracket that connects between the sensor and the ball joint piece has snapped. I'm somewhat optimistic that I can fake that, but again, only if I can get the sensor disconnected.

Thank you in advance for any help.

 

This is a standard 3 pin connector, and it ought to have a boot covering since it is under the car. There is a retaining lever that holds it together. You need to push on that lever to lift the retainer up, so that the plug can be pulled out. If it is tight maybe try a small clamp on the lever, so that you can concentrate on just pulling. Pulling back the boot is the first thing, so that you can see it.

 

How can a nearly 8 year old Prius have only 16K miles on it?

A Prius pays for itself when it's driven at least 10K miles per year. Where's the savings if you only
purchase roughly 40 gallons of gas per year?

That headlight leveling sensor is a real HEADACHE! Because you live in Connecticut and said Prius has
likely been situated in CT or nearby, winter (and road salt) take their toll on that grossly unprotected sensor.

I learned, after two prior repair attempts, that the sensor has three places it can rust and make the sensor inoperative. They are:

1) One of more of the three terminals in the male end of the harness connector rusts solid to the plug in the female end. In my case, one of the three fused solid and snapped. I needed a new harness connector in addition to the sensor.

2) The rotating pivot the leveling arm attaches to contains a rubber seal that eventually fails, resulting in limited and eventually no movement of the arm. The leveling arm on my original sensor was nearly rusted solid and did not move freely. This rubber seal is on the outside of the sensor opposite the sensor body. This is the "weakest link".

3) One or more of the brass springs in the sensor case rust out - which is typical

Unfortunately I hit the jackpot - all red sevens! - my sensor failed in all three ways.

Chances are you will need to buy a new or used replacement sensor. All other repairs are band-aids until the sensor fails catastrophically - which it's almost guaranteed to do if you live in the northern states.

I bought a used sensor with the harness connector from a Lexus from a junkyard in Florida. It was like new even though it was 10 years old. Never saw road salt apparently. It did have some sand from one of the beaches, though. For this sensor, I decided to protect the harness connector with an inner tube, zip ties, and waterproof silicone caulk and used the same caulk everywhere there was a screw or exposed seam. I also used the same caulk over the rubber seal on the leveling arm shaft pivot in hopes of keeping some of the salt water out. I'm hoping this sensor will last the remaining years of my car's life. We'll see.

 

If your headlight aim is off, then it is quite likely that the sensor is bad.

 

+1 for Patrick.

This is precisely what was happening with my bad headlight leveling sensor. The headlight aim was incorrect (too low) even though the red triangle and headlight leveling symbol on the MFD were not displayed.

You should repair or replace the bad sensor pronto. Most likely you will need to buy a good used or new sensor.
After you have, the headlight beam aim will automatically adjust to the correct height.

 

boostm3,

Yes, your leveling sensor is toast. Also in CT, mine on my '05 also failed at only 13,000 miles during the winter when it was less than a year old (still under warranty then) with NO warning lights or screen message whatsoever. My headlight spread pattern was just the same as yours (way low & only illuminating things within about 15 to 20 feet max). Anything beyond that distance was absolutely pitch black & I am NOT comfortable "over-driving" my headlights (safe stopping distance for whatever speed you may travel at exceeds the distance you can see ahead---that means you're definitely going to hit whatever you see once it comes into view). The dealer had to order the part & wait for it to come in, so if I had to go out for anything it had to be in the daylight or else plan for way more driving time to get to my destination because at night I could only safely go at about 10 to 15 MPH.

Get it fixed now before something bad happens. If you're not comfortable dis-assembling your own unit & trying to repair it, then find a new one for the $267 that they're supposed to cost & see if you can get the old one off to install the new one yourself & save yourself some money. I would go new because the new one [with the "G" suffix on the part # label (which designates a "countermeasure" part, to correct a known or recognized problem)] was improved somehow to be better able to resist corrosion & failure (my "G" replacement is still working on my car at 136,000 miles).

Ken (in Bolton,Ct)

 

Question about headlight aim: My 2007 headlights are aimed VERY high. I dont know if its because they are HID's and its my first vehicle with those, maybe Im not used to the brightness? But cars are always flashing their high beams at me to get me to turn mine off (they arent on!). Could this be the leveling sensor? I dont have any lights or warnings coming on the dash or MFD...yet.

 

The headlight aim might be misadjusted.

I suggest you call the parts dept at that dealer and inquire about the G prefix. I don't think the retail parts ordering system allows the letter prefix.

 

Is that something I can fix myself? I know the car was in a frontal collision before I bought it. Reading through the Toyota Collision shop papers, everything aesthetic was replaced in the front (bumper, grills, headlights, hood). It happened shortly before I bought it. I bet the lights werent re-aligned after the repairs...