Mirror Select Switch Circuit (LS400)

Remove tilt and telescopic ECU, located behind dash, near steering column. Do not disconnect harness connectors. Using DVOM, backprobe DVOM positive lead to ECU harness connector terminal No. 1 (Brown/Red wire) and connect DVOM negative lead to ECU harness connector terminal No. 5 (White/Black wire). See WIRING DIAGRAMS .
Turn ignition on. Check voltage with switch in different positions. See MIRROR SELECT SWITCH CIRCUIT TEST table. If voltage in all switch positions is within range, diagnose using appropriate MULTIPLEX CONTROL SYSTEMS article. If voltage in either switch positions are out of range, replace side mirror switch. If voltage in both positions is out of range, check power mirror switch. See appropriate heading under TESTING . Replace switch as necessary. If switch is okay, go to next step.
Check harness and connectors between tilt and telescopic ECU and side mirror adjust manual switch. See WIRING DIAGRAMS . Repair or replace harness as necessary. If harness and connectors are okay, replace tilt and telescopic ECU.

MIRROR SELECT SWITCH CIRCUIT TEST