A friend is out of state looking for some help diagnosing an AHC issue. Took the battery out, put it back in and the AHC wont raise. Blinks twice when you try to go from L to N then stops and nothing happens. Is there a calibration procedure for the AHC? or is he looking at a hardware failure?
If there is anyone near Ellensburg Washington with Tech Stream, you could potentially be a life saver.
A long way from Ellensburg Washington, but suggest first ensure that AHC is ON. If OFF, turn AHC system ON by pressing and holding down OFF switch on centre console.
Then as mentioned in earlier replies, suggest start by clearing old Diagnostic Trouble Codes (DTC’s) stored in ECU memory so as not to be confused with old events. Existing faults then will show as new events.
To do this, see part way down second page of attachment, at paragraph 1(d), to see diagram of DLC1 showing pins
E1 and
Tc. (DLC1 is the covered socket in the engine bay, usually with the word “DIAGNOSTIC” on the lid, located as mentioned by
@jahawk).
In case of not using handheld tester (meaning if not using Techstream), clear Diagnostic Trouble Codes (DTC’s) in the following way:
- with Ignition OFF connect terminals E1 and Tc at DLC1. (Note: “SST 09843-1820” is simply a bridging wire. Unnecessary. An unbent metal paperclip is just as good – voltages here are low, around 4.5 volts, but precheck with multimeter if concerned),
- Turn Ignition ON (without starting engine), ignore dashboard lights,
- Depress the brake pedal 8 or more times within 3 seconds,
- When done, remove connector between E1 and Tc,
- DTC’s are now cleared but will return if faults remain.
After that, it gets more ‘interesting’ – but do the easy, basic things first, such as check (including pull and inspect) AHC fuses and relays.
If necessary, go to AHC Diagnostics section of the Factory Service Manual (FSM) for more information -- see
https://lc100e.github.io/manual/, then use index tabs: Repair Manual > DIAGNOSTICS > ACTIVE HEIGHT CONTROL & SKYHOOK TEMS
This covers details for the AHC system which is the same on both LC100 and LX470.
Techstream is important to discover DTC's -- there are methods without Techstream ("without handheld tester" per FSM) but these are very long-winded methods and would try the patience of most people.
As a starter, make sure that power actually is getting to the AHC Electronic Control Unit (ECU) and that wiring harnesses and connectors throughout the AHC system are at least free of obvious visible damage.
If necessary, methodically check resistance, continuity and voltage responses as indicated for various components where fault conditions (DTC's) are indicated or suspected.
