Instrument Panels: Other Lexus LS III

BULB CIRCUIT

Note. If Lexus hand-held tester is not available, begin testing with step 2).

1. Connect Lexus hand-held tester to Data Link Connector No. 3 (DLC3). With tester in ACTIVE TEST mode, operate appropriate indicator/warning lights. If light operation is okay, perform next check listed in appropriate symptom diagnosis table. See «TROUBLE SHOOTING»(ref-27121-S41900756402001010800000). If light operation is not okay, go to next step.
2. Check combination meter 22-pin connector at circuit plate. (Scheme 2) See «INSTRUMENT CLUSTER CIRCUIT PLATE»(ref-27121-S34745457152001010800000) under COMPONENT TESTS. Repair as necessary. If voltages are to specification, replace instrument cluster.

BUZZER CIRCUIT

Note. If Lexus hand-held tester is not available, begin testing with step 2).

1. Connect Lexus hand-held tester to Data Link Connector No. 3 (DLC3). With tester in ACTIVE TEST mode, operate buzzer. If buzzer operation is okay, perform next check listed in appropriate symptom diagnosis table. See «TROUBLE SHOOTING»(ref-27121-S41900756402001010800000). If buzzer operation is not okay, go to next step.
2. Check combination meter 22-pin connector at circuit plate. (Scheme 2) See «INSTRUMENT CLUSTER CIRCUIT PLATE»(ref-27121-S34745457152001010800000) under COMPONENT TESTS. Repair as necessary. If voltages are to specification, replace instrument cluster.

DRIVER DOOR COURTESY SWITCH CIRCUIT

Remove door courtesy switch. Ensure continuity is present between switch terminals and switch body with switch on (pin released). No continuity should be present between terminals and switch body with switch off (pin pushed in). Replace switch as necessary.

Scheme 2

1. Check GAUGE, MPX-B2 and DOME fuses (10-amp). Replace fuse(s) if necessary. If fuses are okay, go to next step.
2. Remove instrument cluster. See «INSTRUMENT CLUSTER»(ref-27121-S15332993652001010800000) under REMOVAL & INSTALLATION. Disconnect 22-pin connector. (Scheme 2) Measure voltage between connector terminals No 12 and 13, and between terminals No. 1 and 11. (Scheme 2) If battery voltage is present, perform next check listed in appropriate symptom diagnosis table. See «TROUBLE SHOOTING»(ref-27121-S41900756402001010800000). If battery voltage is not present, go to next step.
3. Check for open in harness or connector between ground circuit of combination meter and chassis ground. See «WIRING DIAGRAMS»(ref-27121-S36054494612001010800000). Repair as necessary. If circuit is okay, repair faulty power source circuit between combination meter and battery.

ENGINE COOLANT TEMPERATURE GAUGE CIRCUIT

Note. If Lexus hand-held tester is not available, begin testing with step 2).

1. Connect Lexus hand-held tester to Data Link Connector No. 3 (DLC3). With tester in ACTIVE TEST mode, operate engine coolant temperature gauge. If engine coolant temperature gauge needle moves as commanded by tester, perform next check listed in appropriate symptom diagnosis table. See «TROUBLE SHOOTING»(ref-27121-S41900756402001010800000). If engine coolant temperature gauge needle does not move as commanded by tester, go to next step.
2. Check engine coolant temperature gauge. See «ENGINE COOLANT TEMPERATURE GAUGE»(ref-27121-S15808993952001010800000) under COMPONENT TESTS. Repair as necessary. If engine coolant temperature gauge is okay, go to next step.
3. Check engine coolant temperature gauge sending unit. See «ENGINE COOLANT TEMPERATURE GAUGE»(ref-27121-S15808993952001010800000) under COMPONENT TESTS. Repair as necessary. If engine coolant temperature gauge sending unit is okay, go to next step.
4. Check combination meter 22-pin connector at circuit plate. (Scheme 2) See «INSTRUMENT CLUSTER CIRCUIT PLATE»(ref-27121-S34745457152001010800000) under COMPONENT TESTS. Repair as necessary. If voltages are to specification, replace instrument cluster.

FUEL GAUGE CIRCUIT

Note. If Lexus hand-held tester is not available, begin testing with step 2).

1. Connect Lexus hand-held tester to Data Link Connector No. 3 (DLC3). With tester in ACTIVE TEST mode, operate fuel gauge. If fuel gauge needle moves as commanded by tester, perform next check listed in appropriate symptom diagnosis table. See «TROUBLE SHOOTING»(ref-27121-S41900756402001010800000). If fuel gauge needle does not move as commanded by tester, go to next step.
2. Check fuel gauge. See «FUEL GAUGE»(ref-27121-S03358123602001010800000) under COMPONENT TESTS. Repair as necessary. If fuel gauge is okay, go to next step.
3. Check fuel gauge sending units. See «FUEL GAUGE»(ref-27121-S03358123602001010800000) under COMPONENT TESTS. Repair as necessary. If fuel gauge sending unit is okay, go to next step.
4. Check combination meter 22-pin connector at circuit plate. (Scheme 2) See «INSTRUMENT CLUSTER CIRCUIT PLATE»(ref-27121-S34745457152001010800000) under COMPONENT TESTS. Repair as necessary. If voltages are to specification, replace instrument cluster.

With Lexus Hand-Held Tester

1. Using tester connected to Data Link Connector No. 3 (DLC3), enter DATALIST mode. Test drive vehicle and check tachometer parameter. If parameter value changes with engine speed, replace instrument cluster. If parameter value does not change, go to next step.
2. Check harness and connector between instrument cluster and ECM. See «WIRING DIAGRAMS»(ref-27121-S36054494612001010800000) . Repair as necessary. If circuits are okay, repair ignition coil and/or wire harness.

Without Lexus Hand-Held Tester

1. Check harness and connector between instrument cluster and ECM. Repair as necessary. If circuits are okay, go to next step.
2. Check igniter circuit. See appropriate SELF-DIAGNOSTICS article in ENGINE PERFORMANCE. Repair as necessary. If igniter circuit is okay, replace instrument cluster.

MULTI-INFORMATION DISPLAY

Note. If Lexus hand-held tester is not available, begin testing with step 2).

1. Connect Lexus hand-held tester to Data Link Connector No. 3 (DLC3). With tester in ACTIVE TEST mode, operate each display on multi-information display. If multi-information display is okay, perform next check listed in appropriate symptom diagnosis table. See «TROUBLE SHOOTING»(ref-27121-S41900756402001010800000). If multi-information display operation is not okay, check multi-information display switch and wiring. Repair switch and wiring as necessary. If switch and wiring are okay, go to next step.
2. Check combination meter 22-pin connector at circuit plate. (Scheme 2) See «INSTRUMENT CLUSTER CIRCUIT PLATE»(ref-27121-S34745457152001010800000) under COMPONENT TESTS. Repair as necessary. If voltages are to specification, replace instrument cluster.

SEAT BELT WARNING SWITCH CIRCUIT

Note. See BODY CONTROL SYSTEMS - LS430 article.

SPEEDOMETER CIRCUIT

Note. If Lexus hand-held tester is not available, begin testing with step 2).

1. Connect Lexus hand-held tester to Data Link Connector No. 3 (DLC3). With tester in ACTIVE TEST mode, operate speedometer. If speedometer needle moves as commanded by tester, perform next check listed in appropriate symptom diagnosis table. See «TROUBLE SHOOTING»(ref-27121-S41900756402001010800000). If speedometer needle does not move as commanded by tester, go to next step.
2. Check speedometer. See «SPEEDOMETER»(ref-27121-S19023248142001010800000) under COMPONENT TESTS. Repair as necessary. If speedometer is okay, go to next step.
3. Check combination meter 22-pin connector at circuit plate. (Scheme 2) See «INSTRUMENT CLUSTER CIRCUIT PLATE»(ref-27121-S34745457152001010800000) under COMPONENT TESTS. Repair as necessary. If voltages are to specification, replace instrument cluster.

1. Using tester connected to Data Link Connector No. 3 (DLC3), enter DATALIST mode. Test drive vehicle and check speedometer parameter. If parameter value changes with vehicle speed, replace instrument cluster. If parameter value does not change, go to next step.
2. Check harness and connector between instrument cluster and ABS ECU. See «WIRING DIAGRAMS»(ref-27121-S36054494612001010800000) . Repair as necessary. If circuits are okay, check speed sensor circuit. See appropriate ANTI-LOCK/TRACTION CONTROL SYSTEMS article in BRAKES.

1. Check harness and connector between instrument cluster and ABS ECU. See «WIRING DIAGRAMS»(ref-27121-S36054494612001010800000) . Repair as necessary. If circuits are okay, go to next step.
2. Check speed sensor circuit. See appropriate ANTI-LOCK/TRACTION CONTROL SYSTEMS article in BRAKES. Repair as necessary. If speed sensor circuit is okay, replace instrument cluster.

TACHOMETER CIRCUIT

Note. If Lexus hand-held tester is not available, begin testing with step 2).

1. Connect Lexus hand-held tester to Data Link Connector No. 3 (DLC3). With tester in ACTIVE TEST mode, operate tachometer. If tachometer needle moves as commanded by tester, perform next check listed in appropriate symptom diagnosis table. See «TROUBLE SHOOTING»(ref-27121-S41900756402001010800000). If tachometer needle does not move as commanded by tester, go to next step.
2. Check tachometer. See «TACHOMETER»(ref-27121-S08634249812001010800000) under COMPONENT TESTS. Repair as necessary. If tachometer is okay, go to next step.
3. Check combination meter 22-pin connector at circuit plate. (Scheme 2) See «INSTRUMENT CLUSTER CIRCUIT PLATE»(ref-27121-S34745457152001010800000) under COMPONENT TESTS. Repair as necessary. If voltages are to specification, replace instrument cluster.

BRAKE WARNING LIGHT

Disconnect electrical connector from brake fluid level warning switch. Release parking brake. Connect a jumper wire between brake fluid level warning switch wiring harness connector terminals. Turn ignition on. If brake warning light illuminates, circuit and LED are okay. If brake warning light does not illuminate, check LED.

DOOR OPEN DETECTION SWITCH

Disconnect door open detection courtesy switch connector. Ground terminal No. 1 on wire harness side. If warning light comes on, switch is okay. If warning light does not come on, check LED or wiring.

Engine Coolant Temperature Gauge Resistance

Remove instrument cluster. See INSTRUMENT CLUSTER under REMOVAL & INSTALLATION. Measure resistance between specified gauge terminals on back of instrument cluster. See ENGINE COOLANT TEMPERATURE GAUGE RESISTANCE table. (Scheme 3) If resistance is not as specified, replace engine coolant temperature gauge.

ENGINE COOLANT TEMPERATURE GAUGE RESISTANCE

Scheme 3

Engine Coolant Temperature Gauge Sending Unit

Remove engine coolant temperature gauge sending unit. Submerge tip of sending unit in container of water. Heat water to specified temperature while measuring sending unit resistance. See ENGINE COOLANT TEMPERATURE GAUGE SENDING UNIT RESISTANCE table. If resistance is not as specified, replace engine coolant temperature gauge sending unit.

ENGINE COOLANT TEMPERATURE GAUGE SENDING UNIT RESISTANCE

FUEL GAUGE

Note. To check low fuel level warning light, see warning light circuit plate under INSTRUMENT CLUSTER CIRCUIT PLATE .

Fuel Gauge & Circuit

Disconnect 4-pin connector from main fuel gauge sending unit. Disconnect battery for 30 seconds, then reconnect battery. Turn ignition on and observe fuel gauge needle. (Scheme 4) Gauge needle should move to EMPTY position. Reconnect main sender gauge. Disconnect 3-pin connector from sub-sender gauge. (Scheme 5) Disconnect battery for 30 seconds, then reconnect. Turn ignition on and observe gauge needle. Gauge needle should move to EMPTY position. If gauge operates as specified, check fuel gauge sending unit. See FUEL GAUGE SENDING UNIT. If gauge does not operate as specified, check fuel gauge resistance. See FUEL GAUGE RESISTANCE.

Scheme 4

Scheme 5

Fuel Gauge Resistance

Remove instrument cluster. See INSTRUMENT CLUSTER under REMOVAL & INSTALLATION. Measure resistance between specified terminals on back of instrument cluster. See FUEL GAUGE RESISTANCE table. (Scheme 6) If resistance is not as specified, replace fuel gauge.

FUEL GAUGE RESISTANCE

Scheme 6

Fuel Gauge Main Sending Unit & Sub-Sending Unit

1. To check fuel gauge sub-sending unit, go to next step. To check fuel gauge main sending unit, remove fuel gauge main sending unit. Apply 5 volts to terminals No. 2 and 3 of fuel gauge sending unit 3-pin harness connector. Measure voltage between terminals No. 1 and 3 while moving float to specified positions. (Scheme 7) See «FUEL GAUGE SENDING UNIT VOLTAGE»(ref-27121-S30198025742001010800000) table. If voltage is not as specified, replace fuel gauge main sending unit.
2. Remove fuel gauge sub-sending unit. Apply 5 volts to terminals No. 1 and 3 of fuel gauge sending unit 3-pin harness connector. Measure voltage between terminals No. 1 and 2 while moving float to specified positions. (Scheme 8) See «FUEL GAUGE SENDING UNIT VOLTAGE»(ref-27121-S30198025742001010800000) table. If voltage is not as specified, replace fuel gauge main sending unit.

FUEL GAUGE SENDING UNIT VOLTAGE

Scheme 7

Scheme 8

Combination Meter Circuit

Disconnect instrument cluster circuit plate 22-pin harness connector. (Scheme 2) Check voltage between specified harness connector (harness side) terminal and ground. See COMBINATION METER CIRCUIT VOLTAGE CHECK table. If voltages are not to specification, replace wiring harness.

COMBINATION METER CIRCUIT VOLTAGE CHECK

Resistance Check

Disconnect light rheostat control 8-pin connector. Connect ohmmeter between rheostat control terminals No. 1 and 2. With knob turned slowly clockwise, resistance should change from 0-10 k/ohms. (Scheme 9) Connect ohmmeter between connector terminals No. 1 and 3. Resistance should be 10 k/ohms. If resistances are not to specification, replace rheostat control.

Scheme 9

Tail Cancellation Check

Note. Tail cancellation refers to turning light control rheostat clockwise beyond moderate position, causing lights to illuminate fully and system to ignore automatic light control sensor.

Disconnect light rheostat control 8-pin connector. With knob turned fully clockwise, no continuity should be present. Turn Connect ohmmeter between rheostat control terminals No. 3 and 4.

PARKING BRAKE SWITCH

Disconnect electrical connector from parking brake switch (located on parking brake). Check continuity between parking brake switch terminal and switch body. With switch pin released (switch on), continuity should be present. With switch pin pressed (switch off), continuity should not be present. If continuity is not as specified, replace parking brake switch.

SEAT BELT BUCKLE SWITCH

Disconnect seat belt buckle switch 4-pin connector. With belt fastened, check for continuity between buckle switch 4-pin connector terminals No. 2 and 4. (Scheme 10) With belt fastened, continuity should be present. With belt unfastened, continuity should not be present. If continuity is not as specified, replace seat belt buckle switch.

Scheme 10

SEAT BELT WARNING LIGHT

Disconnect seat belt warning light connector. Turn ignition on. If warning light comes on, system is okay. If warning light does not come on, check LED and wiring. See WIRING DIAGRAMS .

SEAT BELT WARNING OCCUPANT DETECTION SENSOR

Disconnect occupant detection sensor 2-pin connector. Connect ohmmeter between connector terminals. Continuity should be present when occupant detection sensor is depressed. If continuity is not as specified, replace sensor.

Speedometer Resistance

Remove instrument cluster. See INSTRUMENT CLUSTER under REMOVAL & INSTALLATION. Measure resistance between specified terminals on back of instrument cluster. (Scheme 11) See SPEEDOMETER RESISTANCE table. If resistance is not as specified, replace speedometer.

Scheme 11

SPEEDOMETER RESISTANCE

Tachometer Resistance

Remove instrument cluster. See INSTRUMENT CLUSTER under REMOVAL & INSTALLATION. Measure resistance between specified terminals on back of instrument cluster. (Scheme 12) See TACHOMETER RESISTANCE table. If resistance is not as specified, replace tachometer.

Scheme 12

TACHOMETER RESISTANCE

TWIN TRIP & ODOMETER SWITCH

Disconnect 3-pin electrical connector from twin trip and odometer (ODO) switch. Using an ohmmeter, check for continuity between specified switch terminals with switch in specified position. (Scheme 13) See TWIN TRIP & ODO SWITCH CONTINUITY table. If continuity is not as specified, replace twin trip and odometer (ODO) switch.

TWIN TRIP & ODO SWITCH CONTINUITY

Scheme 13

INSTRUMENT CLUSTER

Note. For instrument cluster removal information (Scheme 14)

Scheme 14

Scheme 15

Scheme 16

Scheme 17

1. Remove 6 screws and remove cover from meter case. (Scheme 15) Remove 8 screws and telltale light assembly. (Scheme 16) Disconnect flat circuit plate printed circuit. Remove 4 screws and meter ECU plate assembly. (Scheme 17)
2. Remove meter case and meter circuit plate, using care not to break 5 tabs on meter case. Remove one screw and remove meter glass and meter plate. To assemble, reverse disassembly procedure.

Instrument Panel Wiring Diagram (LS430). Scheme 18