Troubleshooting AHC Ride Height Sensor (1 Viewer)

[benn]

All,
I'm attempting to troubleshoot an issue with the AHC on my 2003 LX470 and just want to check and make sure my logic is sound. Recently, I noticed the front end seemed very high, as in nose up. The interior indicator shows "N" but the front is definitely higher and ride is uncomfortable/bouncy. If I try to select L or H, it seems to be intermittent on whether it will change, sometimes it just flashes and stays at N. Sorry, no Techstream but I assume a ride height sensor issue since interior indications are normal.

My question is on how best to troubleshoot which ride height sensor is bad - or if my logic is completely jacked somehow. When I disconnect the drivers side sensor and start the car, the front end lowers 2 inches or so and looks to be normal height. If i connect the drivers side back up, it raises back up very high (with interior still showing N). If i do the same with the passenger side, there is no change. This makes me think the drivers side ride height sensor is the issue. I removed it to take a look and it is very clean. I still cleaned it up and applied some dielectric grease to the connections but same issue.

2003 LX470
103,000 miles
Stock

Thanks for any assistance.

Ben

 

[l3n0x]

Deleted because of bad advice

 

[uHu]

You removed it and cleaned the inside, or the outside?
Disconnect it and measure it with a multimeter set to ohms. Check that you have a continuous change of ohms over the whole range, and to both sides. There are threads in here on how to.

 

[benn]

uHu,
Thanks for the response. I cleaned up the inside, both looked pretty clean beforehand so I'm not sure it did much. I measured the resistance like you said and had a decrease throughout the arc. Also had good continuity between the spring contacts and the pigtail ends.
Now I'm totally confused. I put everything back on and started it up. Front end went to full height, though the indicator showed L. I again disconnected the passenger sensor, no change. I plugged it back in and disconnected the driver sensor, and it went full lowrider mode, with the indicator still in L. Plugged it back in and no movement, couldn't select N, and it stayed in lowrider mode.

All I can figure is that I have a bad intermittent connection somewhere, or I am misunderstanding the system. Thanks again for your insight.

Ben

 

[uHu]

check the rear sensor as well, even if it's the front acting up.
And connect TechStream to read sensor values

 

[Biga27110]

Incase you want to replace sensors, i have, you can use toyota camry head light leveling sensors because they are the same exact part but only like 25 bucks.

I've had no issues.

 

[benn]

uHu, I checked the rear sensor and it looks clean/same as front. I know I need to get Techstream running, especially if I"m going to keep the AHC on this thing. Based on my understanding (limited) of the system though, it seems like it has to be a sensor issue. Do you know how the two front interface? IE if they read different or one malfunctions, does the computer take the average heigh of the two and raise/lower based on selection? Just curious how the computer interprets the signals. Thanks again.

Biga27110, I haven't heard of this before. This morning I ordered both front ride height sensors off RockAuto.com for about $290 shipped. You put Camry sensors on your LX and they work with the AHC? Thanks.

Ben

 

[Biga27110]

uHu, I checked the rear sensor and it looks clean/same as front. I know I need to get Techstream running, especially if I"m going to keep the AHC on this thing. Based on my understanding (limited) of the system though, it seems like it has to be a sensor issue. Do you know how the two front interface? IE if they read different or one malfunctions, does the computer take the average heigh of the two and raise/lower based on selection? Just curious how the computer interprets the signals. Thanks again.

Biga27110, I haven't heard of this before. This morning I ordered both front ride height sensors off RockAuto.com for about $290 shipped. You put Camry sensors on your LX and they work with the AHC? Thanks.

Ben

get the camry ones ill look up the ones i bought.

 

[Biga27110]

I cant find the one i bought in my Amazon orders for some reason but to give you an idea it was something like this but i cant tell you if it was this one. If you search the forums you will figure it out thats where i learned.

Amazon product ASIN B072WQ8M3D

 

[uHu]

....Do you know how the two front interface? IE if they read different or one malfunctions, does the computer take the average heigh of the two and raise/lower based on selection? Just curious how the computer interprets the signals. ...

As long as you have normal, stable signals from the sensors, the ECU will average the two fronts. If the difference between the two becomes too large (one wheel up/stuffed, one wheel down) the manual height control is disabled.

Yes, you really need TechStream or similar.

The cables to the sensors sometimes give up, especially at the fronts, e.g. where the tiny conductors enter the plug on top of the fender.

 

[benn]

uHu,
Thanks again. I replaced the driver's side sensor and everything is back to normal.
It is frustrating troubleshooting when the symptoms aren't consistent. I can only guess the old ride height sensor was giving erratic indications causing erratic AHC movement. Thanks again for the help. Issue is resolved.

Ben

 

[flintknapper]

uHu,
Thanks again. I replaced the driver's side sensor and everything is back to normal.
It is frustrating troubleshooting when the symptoms aren't consistent. I can only guess the old ride height sensor was giving erratic indications causing erratic AHC movement. Thanks again for the help. Issue is resolved.

Ben

Glad you got it sorted out Ben and thanks for the follow up. Many times folks do not post the remedy/conclusion to issues and it benefits no one. But when folks like you follow-up....it helps the next guy doing a 'search'.