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Mirror Select Switch Circuit

NOTE: If LEXUS scan tool is available, start test from step 1). If this scan tool is not available, start test from step 2).
  1. Connect LEXUS scan tool to Data Link Connector 3 (DLC3) located under left side of instrument panel. Turn ignition and scan tool on. Select DATA LIST mode on scan tool. Check voltage while operating mirror select switch. Operate select switch in each position and note voltage reading. See MIRROR SELECT SWITCH VOLTAGE  table. If all voltages are as specified, go to next test listed in SYMPTOM DIAGNOSIS  table under TROUBLE SHOOTING. If all voltages are not as specified, go to step  3. If voltage in only certain directions is not as specified, replace mirror switch.
  2. If scan tool is not available, remove tilt and telescopic ECU from its mounting, leaving wiring harness connector attached. Turn ignition on. Measure voltage by backprobing rear of terminal No. 19 (Light Green wire) with voltmeter positive lead and by backprobing rear of terminal No. 6 (Brown/Red wire) with negative lead at 22-pin ECU harness connector T9. See Figure. Operate manual switch in each position and note voltage reading. See MIRROR SELECT SWITCH VOLTAGE  table. If all voltages are as specified, go to next test listed in SYMPTOM DIAGNOSIS  table under TROUBLE SHOOTING. If all voltages are not as specified, go to next step. If voltage in only certain directions is not as specified, replace mirror switch.
    MIRROR SELECT SWITCH VOLTAGE

    Switch Position Voltage
    Off 4.70
    Left .65-.95
    Right Less Than .10
  3. Disconnect 10-pin mirror switch harness connector. Using an ohmmeter, measure resistance between terminals No. 8 (White/Black wire) and No. 9 (Brown/Red wire) at mirror switch harness connector. See Figure. Operate select switch in each position and note resistance reading. See MIRROR SELECT SWITCH RESISTANCE  table. If resistances are as specified, go to next step. If resistances are not as specified, replace mirror switch.
    MIRROR SELECT SWITCH RESISTANCE

    Switch Position Ohms
    Left 100
    Right 0
  4. Check wiring harness and connectors between tilt and telescopic ECU and select switch. See WIRING DIAGRAMS . Repair or replace as necessary. If wiring harness and connectors are okay, check tilt and telescopic ECU. See TILT & TELESCOPIC ECU PIN VOLTAGE TESTS  under COMPONENT TESTS. Replace tilt and telescopic ECU as necessary and retest system operation.
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