Power Tilt Steering Column Systems: Other Lexus LS III

ACTUATOR POWER SOURCE CIRCUIT

1. Turn ignition off. Remove tilt and telescopic ECU from its mounting, leaving wiring harness connector attached. Turn ignition on. Measure voltage by backprobing rear of 16-pin connector terminal No. 4 (Blue/White wire) with voltmeter positive lead and by backprobing rear of 8-pin connector terminal No. 6 (White/Black wire) with negative lead. (Scheme 6) If battery voltage does not exist, go to next step. If battery voltage exists, go to next test listed in «SYMPTOM DIAGNOSIS»(ref-27102-S37044165212001010800000) table under TROUBLE SHOOTING.
2. Turn ignition off. Measure resistance between ground and backprobing rear of 8-pin connector terminal No. 6 (White/Black wire). If resistance is one k/ohm or less, go to next step. If resistance is more than one k/ohm, repair or replace wiring harness or connector between tilt and telescopic ECU and ground connection. See «WIRING DIAGRAMS»(ref-27102-S34930120742001010800000).
3. Check continuity of TI and TE fuse located in instrument panel junction block, under left side of instrument panel. If continuity does not exist, check and repair short in wiring harness between fuse and all components connected to fuse. See «WIRING DIAGRAMS»(ref-27102-S34930120742001010800000). If continuity exists, check for open circuit in wiring harness between tilt and telescopic ECU and battery. Repair or replace as necessary and retest system operation.

Scheme 6

ECU POWER SOURCE CIRCUIT

1. Turn ignition off. Remove tilt and telescopic ECU from its mounting, leaving wiring harness connector attached. Turn ignition on. Measure voltage by backprobing rear of 8-pin connector terminals No. 1 (Red/Black wire) and No. 6 (White/Black wire). (Scheme 6) If battery voltage does not exist, go to next step. If battery voltage exists, go to next test listed in «SYMPTOM DIAGNOSIS»(ref-27102-S37044165212001010800000) table under TROUBLE SHOOTING.
2. Measure resistance between 8-pin connector terminal No. 6 (White/Black wire) and ground. If resistance is one k/ohm or less, go to next step. If resistance is more than one k/ohm, repair or replace wiring harness or connector between tilt and telescopic ECU and ground connection. See «WIRING DIAGRAMS»(ref-27102-S34930120742001010800000).
3. Check continuity of MPX-B3 fuse located in instrument panel junction block, under left side of instrument panel. If continuity does not exist, check and repair short in wiring harness between MPX-B3 fuse and all components connected to fuse. See «WIRING DIAGRAMS»(ref-27102-S34930120742001010800000). If continuity exists, check for open in wiring harness between tilt and telescopic ECU and battery. Repair or replace as necessary and retest system operation.

SENSOR POWER SOURCE CIRCUIT

1. Turn ignition on. Remove tilt and telescopic ECU from its mounting, leaving wiring harness connector attached. Measure voltage by backprobing rear of 16-pin connector terminals No. 13 (Black/Blue wire) and No. 14 (Yellow wire). (Scheme 6) Measure voltage by backprobing rear of 16-pin connector terminals No. 10 (White/Blue wire) and No. 12 (White/Red wire). If voltage is not 4.5-5.5 volts for both measurements, go to step 3. If voltage is 4.5-5.5 volts for both measurements, go to next step.
2. Check wiring harness and connectors for an open circuit between 16-pin connector terminals No. 10 (White/Blue wire), No. 12 (White/Red wire), No. 13 (Black/Blue wire) and No. 14 (Yellow wire). See «WIRING DIAGRAMS»(ref-27102-S34930120742001010800000). Repair or replace as necessary. If wiring harness and connectors are okay, go to next test listed in «SYMPTOM DIAGNOSIS»(ref-27102-S37044165212001010800000) table under TROUBLE SHOOTING.
3. Check wiring harness and connectors for a short circuit between 16-pin connector terminals No. 10 (White/Blue wire), No. 12 (White/Red wire), No. 13 (Black/Blue wire) and No. 14 (Yellow wire). See «WIRING DIAGRAMS»(ref-27102-S34930120742001010800000). Repair or replace as necessary. If wiring harness and connectors are okay, check tilt and telescopic ECU. See «TILT & TELESCOPIC ECU PIN VOLTAGE TESTS»(ref-27102-S34414153582001010800000) under PIN VOLTAGE TESTS. Replace tilt and telescopic ECU as necessary and retest system operation.

TELESCOPIC MOTOR 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 ACTIVE TEST mode on scan tool. Using scan tool, telescope steering column in and out. If steering column does not move, go to next step. If steering column moves, go to next test listed in «SYMPTOM DIAGNOSIS»(ref-27102-S37044165212001010800000) table under TROUBLE SHOOTING.
2. Turn ignition off. Disconnect 8-pin telescopic motor and 8-pin tilt motor harness connectors. Remove telescopic motor. Reconnect tilt motor harness connector to telescopic motor. Turn ignition on. Operate tilt and telescopic manual switch and confirm operation of telescopic motor. If telescopic motor operates, go to next step. If telescopic motor does not operate, replace telescopic motor and retest system operation.
3. Check wiring harness and connectors between tilt and telescopic ECU and telescopic motor. See «WIRING DIAGRAMS»(ref-27102-S34930120742001010800000) . Repair or replace as necessary. If wiring harness and connectors are okay, go to next test listed in «SYMPTOM DIAGNOSIS»(ref-27102-S37044165212001010800000) table under TROUBLE SHOOTING.

TILT MOTOR 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 ACTIVE TEST mode on scan tool. Using scan tool, tilt steering column up and down. If steering column does not move, go to next step. If steering column moves, go to next test listed in «SYMPTOM DIAGNOSIS»(ref-27102-S37044165212001010800000) table under TROUBLE SHOOTING.
2. Turn ignition off. Disconnect 8-pin tilt motor and 8-pin telescopic motor harness connectors. Remove tilt motor. Reconnect telescopic motor harness connector to tilt motor. Turn ignition on. Operate tilt and telescopic manual switch and confirm operation of tilt motor. If tilt motor operates, go to next step. If tilt motor does not operate, replace tilt motor and retest system operation.
3. Check wiring harness and connectors between tilt and telescopic ECU and tilt motor. See «WIRING DIAGRAMS»(ref-27102-S34930120742001010800000) . Repair or replace as necessary. If wiring harness and connectors are okay, go to next test listed in «SYMPTOM DIAGNOSIS»(ref-27102-S37044165212001010800000) table under TROUBLE SHOOTING.

TILT & TELESCOPIC MANUAL SWITCH CIRCUIT

1. Connect LEXUS scan tool to Data Link Connector 3 (DLC3) located under left side of instrument panel. Turn ignition and scan tool on. Check tilt and telescopic manual switch using DATA LIST mode on scan tool. See «TILT & TELESCOPIC MANUAL SWITCH»(ref-27102-S28025883862001010800000) table. If switch is okay, go to next test listed in «SYMPTOM DIAGNOSIS»(ref-27102-S37044165212001010800000) table under TROUBLE SHOOTING. If switch is not okay, replace combination switch. TILT & TELESCOPIC MANUAL SWITCH Switch Name (Tester Display) Not Depressed Depressed Telescopic Short Switch (TELESC SHORT SW) OFF ON Telescopic Long Switch (TELESC LONG SW) OFF ON Telescopic Down Switch (TELESC DOWN SW) OFF ON Telescopic Up Switch (TELESC UP SW) OFF ON

TILT & TELESCOPIC ECU PIN VOLTAGES

Turn ignition on. Using DVOM, measure voltage by backprobing between the following tilt and telescopic ECU harness connector terminals. See TILT & TELESCOPIC ECU PIN VOLTAGES table. (Scheme 6) If voltages are not as specified, repair wiring harness or replace components as necessary. If voltages are as specified, replace tilt and telescopic ECU.

TILT & TELESCOPIC ECU PIN VOLTAGES