AHC stuck in LOW, extra liter of AHC fluid accumulating in reservoir?? (1 Viewer)

[porkandcorn]

Decided randomly to check the AHC fluid level after I noticed the system blinking at HI mode last week, when trying to clear an obstacle. Found that it was 550ml over the high mark. Had to drive about 200 miles carefully in LOW mode to get home, when the system stopped being able to get to N mode that same day. Now, the fluid level is about 1Liter over the high mark.

Curious what could cause the AHC fluid to accumulate like that in the reservoir? The pump sounds like it is not pushing any fluid through, and the AHC fluid itself is discolored, transparent brown. The AHC system was working great, and then suddenly all this happened. About 150K miles on my 2006 LC, and all 4 globes were replaced about a year ago, and well as a full fluid bleed and replacement. I'm, obviously, concerned about the pump sounding like it's running dry. Those are not cheap when they are ruined.

 

[BullElk]

I suggest applying direct voltage to the pump from the battery and see if it runs and how it sounds. It should sound run rather quiet and smooth. If if doesn’t, it is not terribly difficult to take apart and clean.

The power plug is the black one towards front of vehicle.

 

[Moridinbg]

First check for DTCs, they can outright tell you what is wrong.

You can also try the active test described here.

DLC1 is the port in the middle of the passenger side in the engine bay with a plastic cap "DIAGNOSTICS" The SST is a bent paperclip or a piece of wire.
If it doesn't move during the test, then it usually is either the pump or the height sensors.

Really, you should start with reading the error codes via Techstream, otherwise it's shooting in the dark. Much more likely to be a bad sensor, than the pump.

If you get to disassembling the pump, check out the last couple of pages of this thread - AHC pump out? - https://forum.ih8mud.com/threads/ahc-pump-out.1226629/page-5 lots of useful info there.

 

[porkandcorn]

thanks Moridinbg!