AHC, back really high

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samwise

samwise

10 Year 15 Year
Joined
May 4, 2008
Threads
40
Messages
376
Location
Northwest Montana
I have a 01 Lx470, 83k. Yesterday it started doing the major stinkbug, back is ridiculously high: Like below, not my truck, but mine is similar.

I have searched lots of threads on this , and this is what I have done:
-Tried going up and down, bouncing, driving, etc, the front will lower and raise, the back goes down some in L, but then goes back up.
-NO flashing ahc light, will go to low, even though the back is still a foot high.
-Checked fluid, no visible problems in back etc.
- Removed and inspected all height sensors, one in back, 2 front. They all look brand new, the springs etc are great. I did the back like 3x as it seems this is the problem one, and I cant find anything wrong with it or linkage.

Before this AHC was fine, had one spell where the back went low in the cold this winter.
I dont want to spend a couple hundred bucks on trying to replace parts, as the sensors appear great.
Any ideas on what to try next?
I was going to bleed the system, but read somewhere it has to normal in order to do this.
Any help would be great! The nearest dealer is 2 hours a way,and I dont really want to do that.
Thanks!
https://forum.ih8mud.com/attachment.php?attachmentid=606881&stc=1&d=1330840673
 
Your rear sensor is probably bad; it can look fine but still be worn out. The problem is a bad electrical signal, so it may also be worth checking the plugs for corrosion where the sensor connects to the harness (in case it's the plug rather than the sensor). If you have some electrical contact cleaner try using that for both the plugs and for the interior of the sensor.

If you had another issue, for instance, a bad solenoid then we would expect an error code... the sensor would report the improper position but the system would be unable to correct it. Since there is no error code that implies that the system does not know that there is a problem; ergo the sensor is likely bad.
 
This is a bad sensor (happened to have it handy)...notice that it looks fine, right?

If you look *very* closely at the black traces with the light angled you can see that the midpoint of each of the semicircles is shiny while the ends are still dull black. That is where the fingers have worn through the traces to the backing material over 120,000 miles of scraping back and forth.

J
image-2176960500.webp
image-1787368100.webp
image-668756319.webp
 
Btw: in that second picture; you see the two sets of fingers? Try bending them out a little. That will put more pressure on the traces and, if they are not too far gone, make it work for a little longer.
 
Jon,
You are the man! Thanks so much for information and pictures were priceless. I took it out again for the 4th time and after comparing with yours and looking closely I see what you mean about the shiny worn part.
I ordered a new one, $300 for that little thing seems like such a waste. I spent 2 hours trying to find a cheaper source, other than used ones I couldnt find much.
I wonder if there is some way to recondition it?

Will see if it works when I get it, thanks again I really appreciate the time you took to post up the pics. If your ever in Washington state I owe you one. :beer:

Jon
 
No worries, glad it was helpful!

When it comes to Land Cruisers i am a hedgehog...i only know one thing. :)

Re: sourcing parts; i used Metro Toyota at the time but you might also call Beno or CDan on the board. They have a great reputation.

It seems like there should be a way to recondition them. The traces are some variety of resistive coating but the problem of course is what is it exactly. If we knew then maybe they could be repaired with a paint brush, right? It feels like a waste to throw the old one away when it is virtually fine mechanically.
 
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AHC rear height sensor replaced

Well, 5 minutes and 300 dollars later my problem is fixed. Annoying it cost so much for such a little thing. Must be a cheaper way to do this. Thanks again Jonathn, my wife can load groceries in the back again.
I measured the difference and it was a 7inch difference in normal mode before the new sensor. I was thinking 4" would look pretty good with bigger tires,even 2", but I think it will remain a kid hauler.

Rear height sensor (sensor sub assy) part number 89407-60010

included linkage, oh the toyota one was $10 bucks cheaper. Not sure if other sensors would work and be cheaper if you had the linkage.

Before:
http://i1226.photobucket.com/albums/ee401/jonpatton555/P1010735.jpg

After new sensor: The pulaski was moved a little, but you get the idea.

http://i1226.photobucket.com/albums/ee401/jonpatton555/P1010736.jpg
 
LESS EXPENSIVE AHC REAR SENSOR OPTION

I know this is an old thread, but I had a similar problem with the rear sensor and this post help me and wanted to post some additional info:

Part number for the Rear Sensor ASSEMBLY is: 89407-60010 (as mentioned in this post, and others), and is about $250 - $300.

HOWEVER, in searching the internet for info on this sensor, I came across a DORMAN headlight height sensor (part number 924755) for $55 from amazon, but I'm sure its available elsewhere. Basically, it is just the sensor without the linkage, etc.

Summary:
89407-60010 Rear Sensor ASSEMBLY including linkage $250-$300
Dorman 924755 SENSOR ONLY (as pictured in images in posts above) $55

At startup, my pump was working and would make some height adjustments, but then my off light would blink. Sometimes rear would not adjust. I decided to try replacing the rear sensor. I marked where it was on the bracket, removed it, then replaced the Dorman sensor ($55), and now its working great!

I don't know if this is the same sensor that is used in the fronts as I don't have experience with the fronts.

Hope this helps.

Lee
2000 LC
2004 LX470 with AHC still intact
 
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Julian, on my 2004 LX470 it was a straight up swap for the rear sensor! I suspect the Dorman sensor is what is used in the OEM assembly. I don't have any pictures, but the Dorman sensor was exactly the same as JOnathN's pictures above. Note that the numbers printed on the sensor didn't match anything. I ordered it from Amazon hoping it would be the same, and if not, I would simply return to Amazon. It was the same!

If you search Google images for the assembly part number ("89407-60010") you will see several pictures of the complete assembly.
If you search Amazon (or Google) for the sensor only part number ("924755") you will see the sensor only.

To remove the sensor from the bracket, there are three screws and the bolt on the sensor that connects to the linkage. It was very easy. Take note of the orientation of the arm on the sensor bolt (the arm has a rectangle hole that fits the rectangle on the base of the bolt on the sensor, so the arm can only go on two ways). Sorry if this sounds complicated, it isn't. Look at the pictures of the Dorman sensor on Amazon. Took me about 20 minutes from start to finish. I put the truck on ramps (rear wheels) and jack stands so I could get to the sensor assembly easier. Once you have the old assembly off, it took about 5 minutes to swap the old sensor for the new.

They were exactly the same.

Lee
2000 LC
2004 LX470
 
Wow, this is fantastic info. Thank you for sharing. I'd love to see it in the FAQ section.
 
Just read up on this sensor, it is a modified version of the Mazda sensor used for headlights which also suffered with a lot of failures, sounds familiar. This new sensor has addressed these issues with better sealing and more robust contacts.

You could of found the answer that all people running ahc have been waiting for, time will tell. I might order three and be the Guinea pig as the PO only changed one when mine failed on him.
 
I've ordered one for testing and trial run in a front application. The Dorman images appear to match the "sealing improved" units that came out as a result of the TSB and redesign for improved weather resistance. Will update in a week or two.
 
Paddo, keep us posted on how it goes. Like I said, I installed one last week on my rear sensor, and it was a direct swap.

Lee
 
leej said:
LESS EXPENSIVE AHC REAR SENSOR OPTION

I know this is an old thread, but I had a similar problem with the rear sensor and this post help me and wanted to post some additional info:

Part number for the Rear Sensor ASSEMBLY is: 89407-60010 (as mentioned in this post, and others), and is about $250 - $300.

HOWEVER, in searching the internet for info on this sensor, I came across a DORMAN headlight height sensor (part number 924755) for $55 from amazon, but I'm sure its available elsewhere. Basically, it is just the sensor without the linkage, etc.

Summary:
89407-60010 Rear Sensor ASSEMBLY including linkage $250-$300
Dorman 924755 SENSOR ONLY (as pictured in images in posts above) $55

At startup, my pump was working and would make some height adjustments, but then my off light would blink. Sometimes rear would not adjust. I decided to try replacing the rear sensor. I marked where it was on the bracket, removed it, then replaced the Dorman sensor ($55), and now its working great!

I don't know if this is the same sensor that is used in the fronts as I don't have experience with the fronts.

Hope this helps.

Lee
2000 LC
2004 LX470 with AHC still intact
Click to expand...
Update regarding the Dorman 724-755 headlight sensor (a potentiometer used in certain Lexus, Toyota and Mazda auto headlight leveling systems) for front AHC height sensors applications.
Bottom line: they work just fine and appear to be a functionally equivalent aftermarket option to repair failed front or rear AHC height sensors - we are talking about just the potentiometer, not the whole OE assembly (chassis bracket, adjustable bearing ended linkage, lever arm or intermediate connector cable). I'll do a more comprehensive post when time permits but essentially the Dorman 724-755 sensor/potentiometer has the same installation profile (fit), the same angular range (<180 deg) and very very similar (<5% variance) linear resistance characteristics. Internally the OE sensors are left and right handed, their track configuration and contact block are mirrored, the Dorman sensor matches the right hand sensors' internals and it will install on either side or the rear position. Externally the Dorman aftermarket sensor appears essentially identical to the OE - same connector, mounting arrangement and lever attachment. The only apparent difference internally is that the Dorman sensor has copper contact springs and the OE (2002 build) has what appears to be brass (gold plated?) springs. Both test to approx. 3.5k ohm across the main resistance track.
I replaced a serviceable front sensor with the Dorman aftermarket in the front left, dialed it in with Techstream and its functioning as expected, normal feedback and no performance difference to the OE during road test. I intend to leave it installed to assess durability. More, with pics, later. Thanks to @leej for his initial post.
 
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PADDO said:
Update regarding the Dorman 724-755 headlight sensor (a potentiometer used in certain Lexus, Toyota and Mazda auto headlight leveling systems) for front AHC height sensors applications.
Bottom line: they work just fine and appear to be a functionally equivalent aftermarket option to repair failed front or rear AHC height sensors - we are talking about just the potentiometer, not the whole OE assembly (chassis bracket, adjustable bearing ended linkage, lever arm or intermediate connector cable). I'll do a more comprehensive post when time permits but essentially the Dorman 724-755 sensor/potentiometer has the same installation profile (fit), the same angular range (<180 deg) and very very similar (<5% variance) linear resistance characteristics. Internally the OE sensors are left and right handed, their track configuration and contact block are mirrored, the Dorman sensor matches the right hand sensors' internals and it will install on either side or the rear position. Externally the Dorman aftermarket sensor appears essentially identical to the OE - same connector, mounting arrangement and lever attachment. The only apparent difference internally is that the Dorman sensor has copper contact springs and the OE (2002 build) has what appears to be brass springs. Both test to approx. 3.5k ohm across the main resistance track.
I replaced a serviceable front sensor with the Dorman aftermarket in the front left, dialed it in with Techstream and its functioning as expected, normal feedback and no performance difference to the OE during road test. I intend to leave it installed to assess durability. More, with pics, later. Thanks to @leej for his initial post.
Click to expand...

looking forward to the install pics and detailed writeup on how to do the swap. can you also include the procedure for dialing it in via tech stream, along with a few screenshots?
 
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