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OK, thanks so much for the feedback. I wlll give all this a look in the next couple of days. You rock!!If a new potentiometer hasn't rectified the problem and DTCs won't manually clear (Tc&E1 jumped + brake pushes) then this really suggests a harness issue - DTC 1713 is "rear height control sensor circuit" open or short. The erratic and random height behavior you initially saw is/was indicative of a failing height sensor/mechanism but this won't necessarily throw a code until the system sees either a very low voltage , <0.3v ~ short, or > 4.7v ~ open circuit. If the sensor is in the process of dying through wear/corrosion then it usually provides bad feedback resulting in bad levelling control which is what you saw. Ideally you'd connect Techstream and with just IG on confirm that the sensors are responding to changes in chassis height, jack up/lower the rear and observe the feedback change to the ecu etc. At a minimum put a multimeter on the replacement sensor and confirm its function; about 3900 ohms iirc between pins 1-3, place the wiper at mid displacement and you should read about 1950 ohms 1-2 and 2-3; gently rotate the wiper shaft and observe the resistance changes from min to ~ 3900 ohms between 2-1 and 2-3 depending on which way you rotate the wiper shaft. If you can verify the replacement pot is fine then you'll need to get into harness and connector tracing looking for bad/loose/corroded connectors, chafed wiring, exhaust gas leak burn through and such.
You initially listed several other faults too - 1762 (very common fault that can probably be ignored if it doesn't continually set); 1763 (abnormal over pressure possibly due to solenoid valve failing to open - this is interesting); 1776 (speed sensor circuit - you've got the height sensor override? so not unexpected if the switch has been flicked whilst moving etc) and 1777 (steering signal? my 03 LX FSM doesn't list this as an AHC fault as such, it does come up as a GX fault though so not sure about this sucker). So where too? I'd try and start with a clean slate: clear faults; observe height sensor feedback; post a screen shot of the AHC ecu page up with all parameters; verify the 3 connectors at the ecu are seated properly and that the override wiring was done appropriately with good insulation on the splices and the switch; verify no other wires were inadvertently cut/badly reconnected etc; in Techstream I'd try operating the control valve and accumulator solenoids (you can also operate these manually by shorting Ts&E1 and configuring the height control switch modes); check/clean/reseat each connector.