Another problem with Automatic Headlight Leveling System

Frankly, I'm surprised that your sensor was in such good condition when you disassembled it.

Hopefully your repair will last longer than mine did. But my sensor was a basket case and I said as much.

My advice was sound and it was free. I never said it wouldn't work. I said it might not work.

People like you will discourage me from offering to help the next person who asks.

 

Buddy, you were the one asking for help, not me. You asked some pretty basic questions that you should have been able to figure out on your own.

You went ahead and did the repair anyway despite my opinion on the subject, so what's your beef?

You just can't please some people.

 

Too bad the thread had to degrade, regardless of who's blaming who. Lots of good info here and glad the OP was able to make the repair and save hundreds. That is, after all, the purpose of the forum. And it is encouraging that the sensor was in as good a condition as it was. With the care used in sealing the part from moisture it sounds like there is a good chance of a long life. Good help and good work. Thanks for the procedures.

 

I'm dealing with an aspect of this also. My arm broke (just the one on the Prius sender, fortunately) and it broke because the sensor now requires a tremendous amount of torque to move the arm. (This was a Massachusetts car.) I can move it with a ten millimeter socket and thereby could manually set the (constant) headlight height, alluding to the wish someone expressed for moving the control to the dash and making it manual. The three conductor Toyota rheostat should be readily replaceable with a standard electronics shop unit and the value can be obtained by measuring across the two outside (usually) terminals. It will be something like 10 meg-ohms perhaps. Run the three wires to the dash, drill a hole, solder on three wires, keeping center to the center of the three. If you get the outside two reversed, the control will operate backwards but still work. Back to my question, I can gen up a replacement arm but would appreciate some insight on the possibility of restoring easy movement to the potentiometer.

Regarding the tone of a couple of the responses, I've run into that a lot in life. Men that have a lot of knowledge and are truly helpful, both to friends and acquaintances, but tone is everything with them. It can be like walking on eggshells to have a conversation without setting off a rude response. Their irritation level is just very low compared to wimps such as myself. I look to avoid being offended. You have to slap me in the face or tell me, "the next thing I say is intended to offend you, please act accordingly." With others, you can just look at them the wrong way and you'd think you were trying to date their sister. There are a lot of extremely novice mechanics on this forum. After all, the idea of actually fixing your own car (or anything else for that matter) has just about passed into history. "I could fix those old 60's models but these modrun computer cars can't be worked on without dealer equipment!" I'm slowly coming to the opinion that the current electronics often makes it easier to fix a car. My brother's Saab was running like feces. The code said "evaporative emission system", read "loose gas cap, broken rubber tube, something disconnected". Sure enough, a vacuum hose nipple was looking forlorn with its little hose lying about six inches away. Now in truth, I just looked under the hood, but that's what the code WOULD have said - this has happened before.

I believe that we need to answer all requests with extreme patience and courtesy, regardless of the apparent stupidity of the question. Remember, there are no stupid questions, only stupid people. No, that was a joke. If someone asks a question, it is important to them and they would not have asked if they could figure it out on their own. Let's cut them some slack and SIMPLY answer the question without questioning their parentage. I've been on both ends and common courtesy is ALWAYS indicated, even when one does not feel courteous. After all, we can and should reread what we write before hitting SEND. If it pleases, write rude, then fix it up nice before sending it out into the ether. And please don't shoot the messenger. Most everyone on the forum feels this way, excepting the few that so readily fly off the handle. Learn how to (quietly) accept gentle correction. It will stand you in good stead for every aspect of your life, particularly your job and your marriage and did I mention your relationship with your children? I'm not looking to read an apology but the absence of a rude response would be tremendously appreciated. Remember that "if you can't say something nice then it's better to . . . " saying from dear old mother? I realize that this may be impossible, of course. EDIT: I just reread the last two pages of posts and one of the gentleman's advice is absolutely excellent. So was the tone through 90% of them. Bad day? He is right on about two ramps vs. one. One only works well if nothing but your arm is going underneath. The second one increases clearance by 50%.

Thanks for listening. I hope my legitimate question at the beginning will forgive the rant.

 

I was also wondering if spraying WD40 on the sensor in the area of the moving spindle would help it turn easier or if it would require taking it apart and applying some appropriate grease. This seems like an obvious overlooked engineering flaw in the design of the sensor and maybe even the need for the adjustment at all. But at this point making the sensor more impervious to the elements seems to be the approach.

 

OK, I held off for a long time but here's my saga:
-2005 Prius, currently with 209K
Probably at about 190k, Trangle Of Doom, "problem", headlight.
Pulled the auto-adjuster (a relatively over-engineered solution to notsomuch of a problem, I think). Yep, two springs gone, one tine broken off the spring arm (the one that contacts the (I'm assuming here) carbon traces). Fixed the springs, but got down to one tine in the process, and also one of the plug pins was rusted out and effectively gone.
- Priced new part, Wth???? Yes, the frigging itty bitty piece of plastic was $320. Yeah, right.
- Took my DMM and shot the resistance on the carbon traces. Well, lookee here, the outer loop looks to be about 5k ohms. Let's see if we can shoot for the middle. Go out and purchase one trimmer pot, 5k, Radio Shack (overpriced at $3.79, but at this point that would be over-complaining, don't you think?). Soldered three bare copper wires about the right gauge to the trimmer pot's soldering tabs, in about the right place. Push it into the plug. Adjust the trimmer pot to about the middle.

AWAYYYY goes the magic triangle, and the headlights look great. That's a pretty elegant fix. I wrap a ziploc baggie around the pot/wire/cable, zip tie it (this was not elegant), and voila, away we go.

Months later, the light comes back on. Well, of course it does, I didn't weather-proof the mess enough. I re-do it all, and goober it all up with bathtub caulk. All better.

Until it seems to fail again. Once again, months later. I still think it's all about the abuse it all takes under the car.

I got very tired of trying to make it all work with the plug, and decide to snip off the plug (which was challenged from the rusted-out pin from the adjuster anyway) and solder it directly.

This did not go well, for reasons that are not completely clear.

I snipped off the plug, stripped the corresponding leads (you need to keep track, because of the left-right-middle thing), and attempted to solder the trimmer pot directly to the wires (the new trimmer pot - I blew another big $3.79 on a new one).

Wow. What am I looking at here? The stripped wires are not the same - the center tap is obviously copper, and the other wires are....what? Aluminum? I'm still not sure. But one thing I can tell you: THEY HATE HATE HATE ACCEPTING SOLDER. Hate it. Getting my wires from the trimmer pot to solder successfully just sucks. The center copper wire? No problem. The outer two? Terrible. Also, I'm good at soldering. Considered other options - use flux (the solder I use is fluxed already, but....). I'm hating these wires. Really? Something other than copper? Why? (I want to meet the engineer who spec'd this....)

I reset (myself), take the trimmer pot, and add stranded wires to it (the other wires were solid copper). I clean up all the car wires, and twist the wires together, really well. Then I take a shot at soldering it all. MAYBE it seems to work better. At any rate, it seems to fix the problem.

Months later, it all comes back - Triangle Of Doom, "problem", little light symbol. Sheesh. At this point, the $320 option is looking better (except that: I have no plug, and I tossed the swingarm assembly, which, as I forgot to mention, had separated at one of its joints anyway).

I get under the hood, adjust the star wheels, and the headlights look great. Ah....finally, a nice mechanical fix. Of course, the first time I tried this, I had 'em a bit high - raccoon hunters, I could see way up in the trees. I'm fine-tuning that now. I'm happy with this fix. The last thing I need to do is to MAKE THAT TRIANGLE GO AWAY. This can be with cardboard, or.....

I will say that the manual adjusters work great. I recommend (if you try this):
- mark the star wheel with a Sharpie, or other, so you can count the revolutions.
- I was able to adjust the right one without disassembling anything, but the left one was best served by my undoing to of the fasteners (one is the "pry up the center part of the fastener and then the rest will follow" fasteners, and the other is "use a Phillips screwdriver to unscrew the center and then pry up the outside" fastener), to loosen the outer covering and then remove the air intake - it's a fairly small piece of black plastic that mates up with the air intake, but gets squarely in the way of the adjuster on the left. It's an easy job to remove and replace. I've done it twice so far.
- the adjusters are 8mm. use a 1/4" drive and an 8mm socket, if you have them. Not a lot of swing room - that's why, IMO, you should mark the star wheels so that you can count the revolutions.
- IF you are set up to do so, point the car at the back wall of a garage (I don't have one) or at a wall some feet away - maybe 20' ? - and try a few star wheel revolutions, and see where you go. You can do this with trial and error, of course. The object here is: to see where the hell you're going at night, without locomotive-light-blinding the oncoming drivers. They don't like that much, and you don't benefit either from vision with maladjusted headlights or from the oncoming cars careening into you.

I'm going to try to short out the wires, sequentially, and see if that sends a signal that shuts this thing up. If it does, I'll have to check the mechanical adjustment of the headlights to make sure they are where I want them, as this may cause them to re-adjust "automatically". But if I can make that triangle disappear, I'm good.

At least I can see where the hell I'm going at night. As many have remarked on this thread, having them point about six feet in front of the car "doesn't feel all that useful". Or very safe.

Yes, I'll have the same problem if I can short out two of the leads (center tap/side, either one) and make the warning go away, that I had before - soldering them together. I might consider doing a major twist and use an electrical twist connector cap on them, and then silicon caulk. We'll see.

IF the shorting thing doesn't work, I have one more trick I'd like to try - soldering (ugh), or connecting somehow, a couple of 2.2k ohm resistors - one leg of each one to the center tap, and the other leg of each, individually, to the outer wires. That should roughly imitate the OEM adjuster, with a "adjuster is in about the middle" setting.

I'll chime in and let everyone know what happens.

I would have paid $100 for that cheesy piece of plastic (about the size of a home telephone wall plug, the little square ones). And I would have been pissed about that, but I would have done it. Totally ballsy for them to charge what they charge. Ugh.

Good luck, all.

 

UPDATE:

Crawled under the car (nice weather, cold, rainy). One bad connection on one side of the trimmer pot business. Didn't even bother with the solder, tested with a clip lead (Triangle Of Doom - GONE!!!). Put back together with an electrical twist connector (I'm sure those have a name, but I'm not remembering what that is). More caulk. All better...

...except now I have to wait until it's dark to re-adjust the headlights, manually, as now the Prius is going to think it's all better and shines them....further up into the air.

Ah, the fun never ends.

BTW, this is the best car I have ever owned, nothing else close.

 

OK, one more thing:

For some enterprising soul (I've considered this, and might still) it would be possible to run wiring up to a trimmer pot mounted up front (nicely, I hope) so that the driver could manually adjust the headlights...now wouldn't that be fun?

 

Boy. Been there, done that. I tried to repair the original sensor twice and no dice.

My fix only cost me $50 for a used leveling sensor from a Florida junk yard and $7 for waterproof silicon caulk.

This repair has lasted since July 2012. Hope it lasts until I sell or donate the Prius.

 

jadziasman,

If I had found a used sensor for $50, I'd have done it in a heartbeat. Looked around locally (Vermont) and a bit further, no joy. That's why I went the other route.

Having learned a few things along the way, I think I would recommend this, at this point, if you are not able to round up another sensor for reasonable money:
- buy a 5k potentiometer (I'd say Radio Shack, it's almost all they're good for anymore). (If it has a long shaft, you could cut it pretty short to make it easier to handle, or not. I cut mine.)
- Solder short (maybe 3" lengths) of wire to each trimmer pot tab (you can do this, of course, from the comfort of your own home, as they say). Have the other end stripped, I would guess about 1/2" worth of stripped wire.
- Adjust the trimmer pot to about the middle. mark it with a Sharpie if you need to.
- Cut the plug right off, and strip those wires also about 1/2" bare. On my 2005, the blue wire is the center tap. I don't believe that it matters which ones go to the outsides on the potentiometer, as we're effectively balancing the resistance anyway.
- Here's where I'd do it differently if I had to do it all over: dispense with the solder. As I mentioned, the outside leads are NOT copper, and they hate solder. So, procure some wire nuts - probably a small assortment pack (I finally looked it up - those doohickeys one uses to put electrical wires together, by turning them onto two connected wires), pick out a likely size, and try it out. Do this to all three. Get in car, turn on, wait for Triangle Of Doom to not appear....smile.....
Return to position under car. Make sure wire nuts are nice and tight (turn 'em too tightly, and you break off some of the wire and have to re-do). Apply silicone caulk to: all over/around the wire nuts, all over/around the potentiometer.
- feel free to Zip-tie the wires/pot to the wiring harness, just to keep it from dangling.

If you do this right, that will end this problem. Fine-tuning can be had by: not immediately goobering the business end of the potentiometer, and playing with it a bit (twist it one way, twist it the other way, see what happens...). I'm sorry I didn't try this, I would have liked to see what happened.
Remember, once the warning is gone, if you don't like the height of the lights, either adjust it with the potentiometer until happy (and silicone when you are), or do it with the manual star wheel adjusters. I believe I did find photos of the star wheel adjusters somewhere this forum once.

My guess is that, once you have the parts, you're looking at 30 minutes to do this, tops. Just my guess. Beats the price of that &^#%^$&@ sensor.

 

I needed to search for a while but eventually found one on Ebay. The sensor is common to the Lexus IS250 which has FOUR of them! The sensors on the front struts from the IS250 fit the Prius. The only problem was the connectors didn't match so I had to cut and crimp. As I said, the repair's still functioning properly but who knows how much longer. The original only lasted five winters in N. Indiana and SE Michigan.

 

I hate people who say I told you so.........but, ahem, you know......

 

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