Thought I'd share my fix for this DTC in the hope it helps others. I recently overloaded my 03 LX and it dropped to L, as expected, with L illuminated and OFF flashing. Not concerned at all. On unloading the rear the vehicle raised back to N however OFF remained flashing. Damping had defaulted to the hardest setting. I jumped Tc and E1 of DLC1 and got dtc 43, it would not clear with the standard 9 brake pushes in less than 3 seconds method. A couple of vehicle start/stop cycles did not help either. Connecting Techstream confirmed DTC C1743 was set, it would not clear via Techstream. The relevant DI pages pointed to main relay; main relay cct or AHC ECU as potentially faulty. I attempted to operate the main relay (listen for click as it's located next to the AHC ECU) via Techstream which revealed the relay wasn't actuating, suggesting the main relay was the likely problem. I pulled/replaced the 15A AHC B fuse with no change then pulled/replaced the 20A AHC IG fuse and the main relay clicked, releasing itself. I was then able to clear the fault, OFF stopped flashing and all was back to normal. A bit of googling reveals there is Lexus TSB SU 00203 that applies to some 2002-03 LXs. It identifies the flashing OFF and DTC C1743 but, not being able to locate a full copy, I'm not aware of what the recommended fix or course of action is. I suspect the AHC ECU gets itself into a locked up situation and won't deenergise the main relay, throws C1743, defaults to the hardest damping and stays locked up until the ECU is powered down which, for me, was to pull/replace the AHC IG fuse in the LH kick panel.
Last edited: