Body NO.2 Control System - Diagnostics Lexus GS III

HOW TO PROCEED WITH TROUBLESHOOTING

HINT

The ECU of this system is connected to the multiplex communication system. Therefore, before starting troubleshooting, make sure to check that there is no trouble in the multiplex communication system, refer to MULTIPLEX COMMUNICATION SYSTEM - DIAGNOSTICS .

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Scheme 35

CIRCUIT DESCRIPTION

This circuit provides power to operate the body ECU No. 2.

Scheme 36

INSPECTION PROCEDURE

1. Check ECU-B2 and ECU-IG fuse. CHECK: Check continuity of ECU-B2 and ECU-IG fuse. OK: Continuity NG: Replace the failure fuse. OK: Go to next step.
2. Check voltage between terminals BECU, IG and GND of body ECU No. 2 connector. PREPARATION: Turn ignition switch ON. CHECK: Measure voltage between terminals IG and GND. OK: Voltage: 10 - 14V PREPARATION: Turn ignition switch OFF. Disconnect the body ECU No. 2 connector. CHECK: Measure voltage between terminals BECU and GND. OK: Voltage: 10 - 14V OK: Proceed to next circuit inspection shown on problem symptoms table (See «PROBLEM SYMPTOMS TABLE»(/lexus/gs/iii-2004-2007/remont/communication-devices/#body-no2-control-system-diagnostics) ). NG: Go to next step.
3. Check wire harness and connector between body ECU No. 2 and body ground. NG: Repair or replace wire harness or connector. OK: Check and repair wireharness and connector between body ECU No. 2 and battery.

The key unlock warning switch goes on when the ignition key is inserted in the key cylinder and goes off when the ignition key is removed.

The ECU operates the key confinement prevention function while the key unlock warning switch is on.

Scheme 37

HINT

In case of using the hand-held tester, start the inspection from step 1 and incase of not using the hand-held tester, start from step 2 .

1. Check key unlock warning switch using hand-held tester. PREPARATION: Connect the hand-held tester to the DLC3. CHECK: Check the key unlock warning switch using DATA LIST. NG: Proceed to next circuit inspection shown on problem symptoms table (See «PROBLEM SYMPTOMS TABLE»(/lexus/gs/iii-2004-2007/remont/communication-devices/#body-no1-control-system-diagnostics) ).
2. Check key unlock warning switch (See «INSPECTION»(/lexus/gs/iii-2004-2007/remont/ignition-switchsteering-lock/#ignition-switch-and-key-unlock-warning-switch) ) NG: Replace the key unlock warning switch. OK: Go to next step.
3. Check wire harness and connector between key unlock warning switch and body ECU No. 2. NG: Repair or replace wire harness or connector. OK: Proceed to next circuit inspection shown on problem symptoms table. (See «PROBLEM SYMPTOMS TABLE»(/lexus/gs/iii-2004-2007/remont/communication-devices/#body-no1-control-system-diagnostics) )

Scheme 38

HINT

In case of using the hand-held tester, start the inspection from step 1 and in case of not using the hand-held tester, start from step 2 .

1. Check driver buckle switch using hand-held tester. PREPARATION: Connect the hand-held tester to the DLC 3. CHECK: Check the driver buckle switch using DATA LIST. OK: Proceed to next circuit inspection shown on problem symptoms table. (See «PROBLEM SYMPTOMS TABLE»(/lexus/gs/iii-2004-2007/remont/communication-devices/#body-no2-control-system-diagnostics) ). NG: Go to next step.
2. Check driver buckle switch (See «INSPECTION»(/lexus/gs/iii-2004-2007/remont/gauges-instrument-panels/#combination-meter) ). NG: Replace the driver buckle switch. OK: Go to next step.
3. Check wire harness and connector between driver buckle switch and body ECU No. 2. NG: Repair or replace wire harness or connector. OK: Proceed to next circuit inspection shown on problem symptoms table. (See «PROBLEM SYMPTOMS TABLE»(/lexus/gs/iii-2004-2007/remont/communication-devices/#body-no2-control-system-diagnostics) )

Scheme 39

HINT

In case of using the hand-held tester, start the inspection from step 1 and in case of not using the hand-held tester, start from step 2 .

Scheme 40

1. Check headlight control switch using hand-held tester. PREPARATION: Connect the hand-held tester to the DLC 3. CHECK: Check the headlight control switch using DATA LIST. OK: OK: Proceed to next circuit inspection shown on problem symptoms table (See «PROBLEM SYMPTOMS TABLE»(/lexus/gs/iii-2004-2007/remont/communication-devices/#body-no2-control-system-diagnostics) ). NG: Go to next step.
2. Check headlight control switch (See «INSPECTION»(/lexus/gs/iii-2004-2007/remont/exterior-lights/#headlight-and-tailight-system) ). NG: Replace the headlight control switch. OK: Go to next step.
3. Check wire harness and connector between headlight control switch and body ECU No. 2. NG: Repair or replace wire harness or connector. OK: Proceed to next circuit inspection shown on problem symptoms table. (See «PROBLEM SYMPTOMS TABLE»(/lexus/gs/iii-2004-2007/remont/communication-devices/#body-no2-control-system-diagnostics) )

To detect abnormality of the brake fluid level.

Scheme 41

HINT

In case of using the hand-held tester, start the inspection from step 1 and incase of not using the hand-held tester, start from step 2 .

1. Check brake fluid level warning switch using hand-held tester. PREPARATION: Connect the hand-held tester to the DLC 3. CHECK: Check the brake fluid level warning switch using DATA LIST. REFERENCE Brake fluid level Switch Normal OFF Abnormal ON OK: Proceed to next circuit inspection shown on problem symptoms table (See «PROBLEM SYMPTOMS TABLE»(ref-229359-S21719036492006041400000) ). NG: Go to next step.
2. Check brake fluid level warning switch. (See «INSPECTION»(/lexus/gs/iii-2004-2007/remont/gauges-instrument-panels/#combination-meter) ). NG: Replace the brake fluid level warning switch. OK: Go to next step.
3. Check wire harness and connector between brake fluid level warning switch and body ECU No. 2. NG: Repair or replace wire harness or connector. OK: Proceed to next circuit inspection shown on problem symptoms table. (See «PROBLEM SYMPTOMS TABLE»(ref-229359-S21719036492006041400000) ).

This circuit detects the conditions of the mirror selection switch and the mirror position switch.

Scheme 42

HINT

In case of using the hand-held tester, start the inspection from step 1 and incase of not using the hand-held tester, start from step 2 .

1. Check mirror switch using hand-held tester. PREPARATION: Connect the hand-held tester to the DLC 3. CHECK: Check the mirror switch using DATA LIST. OK: Proceed to next circuit inspection shown on problem symptoms table. (See «PROBLEM SYMPTOMS TABLE»(/lexus/gs/iii-2004-2007/remont/door-locks-anti-theft-systems/#driver-door-control-system-diagnostics) and «PROBLEM SYMPTOMS TABLE»(/lexus/gs/iii-2004-2007/remont/door-locks-anti-theft-systems/#passenger-door-control-system-diagnostics) ). NG: Go to next step.
2. Check mirror switch (See «INSPECTION»(/lexus/gs/iii-2004-2007/remont/mirrors/#power-mirror-control-system) ) NG: Replace the mirror switch. OK: Go to next step.
3. Check wire harness and connector between mirror switch and body ECU No. 2. NG: Repair or replace wire harness or connector. OK: Proceed to next circuit inspection shown on problem symptoms table. (See «PROBLEM SYMPTOMS TABLE»(/lexus/gs/iii-2004-2007/remont/door-locks-anti-theft-systems/#driver-door-control-system-diagnostics) and «PROBLEM SYMPTOMS TABLE»(/lexus/gs/iii-2004-2007/remont/door-locks-anti-theft-systems/#passenger-door-control-system-diagnostics) ).

The Body ECU No. 2 is detecting the condition of the stop light switch.

Scheme 43

HINT

In case of using the hand-held tester, start the inspection from step 1 and in case of not using the hand-held tester, start from step 2 .

1. Check stop light switch using hand-held tester. PREPARATION: Connect the hand-held tester to the DLC 3. CHECK: Check the stop light switch using DATA LIST. OK: Proceed to next circuit inspection shown on problem symptoms table. (See «PROBLEM SYMPTOMS TABLE»(ref-229357-S19388680822006041400000) ). NG: Go to next step.
2. Check stop light switch, see «INSPECTION»(/lexus/gs/iii-2004-2007/remont/exterior-lights/#stop-light-system) ). NG: Replace the stop light switch. OK: Go to next step.
3. Check wire harness and connector between stop light switch and Body ECU No. 2, battery and stop light switch. NG: Repair or replace wire harness or connector. OK: Proceed to next circuit inspection shown on problem symptoms table. (See «PROBLEM SYMPTOMS TABLE»(ref-229357-S19388680822006041400000) ).

Lamp failure sensor detects a wire break of the stop light, high mount stop light and tail light and sends that signal to the Body ECU No. 2.

Scheme 44

HINT

In case of using the hand-held tester, start the inspection from step 1 and incase of not using the hand-held tester, start from step 2 .

1. Check lamp failure sensor using hand-held tester. PREPARATION: Connect the hand-held tester to the DLC 3. CHECK: Remove either bulb of the stop light high mount stop light or tail light, and check the operation of the lamp failure sensor with DATA LIST. REFERENCE Lamp condition Lamp failure sensor (Tester display) Normal OFF Lamp wire break (or removed) ON OK: Proceed to next circuit inspection shown on problem symptoms table. (See «PROBLEM SYMPTOMS TABLE»(ref-229359-S21719036492006041400000) ). NG: Go to next step.
2. Check wire harness and connector between lamp failure sensor and Body ECU No. 2. NG: Repair or replace wire harness or connector. OK: Proceed to next circuit inspection shown on problem symptoms table. (See «PROBLEM SYMPTOMS TABLE»(ref-229359-S21719036492006041400000) ).

Receiving the courtesy signal from either of the door ECU, the Body ECU No. 2 will make the interior light, ignition light, and foot light come on.

Scheme 45

HINT

In case of using the hand-held tester, start the inspection from step 1 and in case of not using the hand-held tester, start from step 2 .

1. Check illumination (interior light, ignition switch light, foot light) using handheld tester. PREPARATION: Connect the hand-held tester to the DLC 3. CHECK: Check that the illumination can light in an ACTIVE TEST. OK: All the illumination should light on. OK: Proceed to next circuit inspection shown on problem symptoms table. (See «PROBLEM SYMPTOMS TABLE»(/lexus/gs/iii-2004-2007/remont/communication-devices/#body-no2-control-system-diagnostics) ). NG: Go to next step.
2. Check illumination light. (See «INSPECTION»(/lexus/gs/iii-2004-2007/remont/ignition-switchsteering-lock/#ignition-switch-and-key-unlock-warning-switch) and «INSPECTION»(/lexus/gs/iii-2004-2007/remont/interiorillumination-lights/#interior-light-system) ). NG: Replace the failure light. OK: Go to next step.
3. Check wire harness and connector between each illumination light and Body ECU No. 2, battery and each illumination light. NG: Repair or replace wire harness or connector. OK: Proceed to next circuit inspection shown on problem symptoms table. (See «PROBLEM SYMPTOMS TABLE»(/lexus/gs/iii-2004-2007/remont/communication-devices/#body-no2-control-system-diagnostics) )

Taillight relay will be "ON" by operating the tail light switch. The transistor which activates the tail light relay has two sorts: one activates by the tail light switch for fail safe and the other activates by CPU.

Scheme 46

HINT

In case of using the hand-held tester, start the inspection from step 1 and in case of not using the hand-held tester, start from step 2 .

1. Check tail light relay using hand-held tester. PREPARATION: Connect the hand-held tester to the DLC 3. CHECK: Check that the tail light relay can operate in an ACTIVE TEST. OK: Proceed to next circuit inspection shown on problem symptoms table. (See «PROBLEM SYMPTOMS TABLE»(/lexus/gs/iii-2004-2007/remont/communication-devices/#body-no1-control-system-diagnostics) ) NG: Go to next step.
2. Check taillight relay. (See «INSPECTION»(/lexus/gs/iii-2004-2007/remont/exterior-lights/#headlight-and-tailight-system) ) NG: Replace the taillight relay. OK: Go to next step.
3. Check wire harness and connector between taillight relay and body ECU No.2, battery and tail light relay. NG: Repair or replace wire harness or connector. OK: Proceed to next circuit inspection shown on problem symptoms table. (See «PROBLEM SYMPTOMS TABLE»(/lexus/gs/iii-2004-2007/remont/communication-devices/#body-no1-control-system-diagnostics) )

Head light relay will be "ON" by operating the head light switch. The transistor which activates the tail light relay has two sorts: one activates directly by the head light switch for fail safe and the other activates by CPU. the one that activates by CPU has two systems and prevents the head light from turning off at the time of one system trouble in the automatic operation circuit.

Scheme 47

HINT

In case of using the hand-held tester, start the inspection from step 1 and in case of not using the hand-held tester, start from step 2 .

1. Check headlight relay using hand-held tester. PREPARATION: Connect the hand-held tester to the DLC 3. CHECK: Check that the headlight relay can operate in an ACTIVE TEST. HINT: If the head light relay is normal, the head light comes "ON". In the case that the head light relay activates but the head light will not come on, check the head light circuit. OK: Proceed to next circuit inspection shown on problem symptoms table. (See «PROBLEM SYMPTOMS TABLE»(/lexus/gs/iii-2004-2007/remont/communication-devices/#body-no1-control-system-diagnostics) ) NG: Go to next step.
2. Check headlight relay. (See «INSPECTION»(/lexus/gs/iii-2004-2007/remont/exterior-lights/#headlight-and-tailight-system) ) NG: Replace the headlight relay. OK: Go to next step.
3. Check wire harness and connector between headlight relay and Body ECU No. 2, battery and head light relay. NG: Repair or replace wire harness or connector. OK: Proceed to next circuit inspection shown on problem symptoms table. (See «PROBLEM SYMPTOMS TABLE»(/lexus/gs/iii-2004-2007/remont/communication-devices/#body-no1-control-system-diagnostics) )

Body ECU No. 2 will send the light deterioration signal to the clock and deteriorate the light.

Scheme 48

HINT

In case of using the hand-held tester, start the inspection from step 1 and in case of not using the hand-held tester, start from step 2 .

1. Check clock using hand-held tester. PREPARATION: Connect the hand-held tester to the DLC 3. CHECK: Check that the clock will deteriorate its light in an ACTIVE TEST. OK: Clock must be deteriorate. OK: Proceed to next circuit inspection shown on problem symptoms table. (See «PROBLEM SYMPTOMS TABLE»(/lexus/gs/iii-2004-2007/remont/communication-devices/#body-no2-control-system-diagnostics) ) NG: Go to next step.
2. Check the clock. (See «CLOCK»(ref-229412) ) NG: Replace the clock. OK: Go to next step.
3. Check wire harness and connector between clock and Body ECU No. 2, battery and clock. NG: Repair or replace wire harness or connector. OK: Proceed to next circuit inspection shown on problem symptoms table. (See «PROBLEM SYMPTOMS TABLE»(/lexus/gs/iii-2004-2007/remont/communication-devices/#body-no2-control-system-diagnostics) )

Body ECU No. 2 receives the generator L signal from ECM through communication and outputs it to the Day time running light relay.

Day time running light relay judges whether the engine rotates or not with this generator L signal and makes the Day time running light turn ON and OFF.

Scheme 49

HINT

In case of using the hand-held tester, start the inspection from step 1 and incase of not using the hand-held tester, start from step 2 .

Scheme 50

1. Check generator L terminal output using hand-held tester. PREPARATION: Connect the hand-held tester to the DLC 3. CHECK: Check the generator L terminal output using DATA LIST. REFERENCE Condition Generator L terminal Engine running ON Engine not running OFF OK: Proceed to next circuit inspection shown on problem symptoms table (See «USA: HEADLIGHT AND TAILLIGHT SYSTEM»(/lexus/gs/iii-2004-2007/remont/body-electrical/#troubleshooting__usa-headlight-and-taillight-system) ). NG: Go to next step.
2. Check RL terminal of ECM. CHECK: Check the voltage of RL terminal of ECM. OK: REFERENCE Condition Voltage Engine running 10 - 14V Engine not running 0V NG: Replace the Body No. 2 ECU. OK: Go to next step.
3. Check wire harness and connector between ECM and generator. NG: Repair or replace wire harness or connector. OK: Repair or replace the generator or regulator.

See also:
• PROBLEM SYMPTOMS TABLE
• INSPECTION
• INSPECTION
• INSPECTION
• PROBLEM SYMPTOMS TABLE
• PROBLEM SYMPTOMS TABLE
• INSPECTION
• INSPECTION
• INSPECTION
• USA: HEADLIGHT AND TAILLIGHT SYSTEM
• PROBLEM SYMPTOMS TABLE