CARspec had the opportunity to address inoperative height control on a 2006 LX470 today and wanted to share the solution, as it stems from a common problem. Unlike complete suspension conversion like on this LX470, this solution was much simpler.
The guest’s initial concern was that the Active Height Control (AHC) indicator would intermittently show “Off” and no long accept inputs from the height control switch on the center console. This is different than a typical AHC failure, as the indicator normally blinks repeatedly to indicate a malfunction. This vehicle’s AHC worked sometimes, othertimes not. The owner ok’d diagnostic time to figure out the root cause and the technician set out to work.
The technician used the Techstream scan tool to watch the AHC sensor heights (two up front, one out back) while lifting the vehicle in the shop – they responded fine. The system logged no diagnostic trouble codes. The technician also noted that the information out of the switch was a constant “Down” command even though the switch wasn’t being pressed. The car was getting a solid signal to lower itself all the time. A visual inspection of the switch was performed and the cause was readily apparent – a soda spill. Here’s the back of the AHC switch’s circuit board with the sticky corrosion highlighted:
AHC switch corrosion
And a better look of the front of the switch where you can see the corrosion shorting out multiple board pins:
AHC Switch Corrosion
The technician tried to check resistance between the various terminals to uncover the exact location of the short but the values were nonsensical. The dampening control (also run through this switch) in addition to the up/down controls had continuity across the board, the switches were all showing partial short, and the connector was too sticky to handle.
A new switch was installed and the AHC performed without flaw.
As Minneapolis’s premier independent Toyota and Lexus repair shop, we pride ourselves on our knowledge of unique systems like the Active Height Control and its quirks. If you have AHC problems or want a second opinion on your LX470/LX570/Land Cruiser’s issue, don’t hesitate to give us a ring at (952)426-4798 and set up and appointment today!
