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Horn: Overview Lexus LS IV

Horns 10 illustrations ~999 words

SYSTEM DESCRIPTION

  1. HORN SYSTEM DESCRIPTION When the steering pad (horn button) is pressed, a signal is sent from the steering pad through the steering pad switch (steering pad ECU) to the spiral cable. The spiral cable and front light ECU (front controller) communicate via the CAN line. The front light ECU receives the signal and sends it to the vehicle horns, causing the horns to sound.
  2. FUNCTION OF MAIN COMPONENT MAIN COMPONENT FUNCTION CHART Component Outline Steering pad (Horn button) Sounds vehicle horns when pressed Vehicle horns (high pitched and low pitched) Sound when steering pad (horn button) is pressed

DESCRIPTION

This DTC is output when one of the following occurs: 1) vehicle horn (high pitched or low pitched) is malfunctioning; 2) front light ECU (front controller) is malfunctioning; or 3) the wire harness between the front light ECU and vehicle horn is open or shorted.

DTC CodeDTC Detection ConditionTrouble Area
B2484Horn system malfunctionHigh pitched horn Low pitched horn Front light ECU (Front controller) Wire harness

DTC DETECTION CONDITION CHART

Scheme 1

Scheme 1: WIRING DIAGRAM
Scheme 1: WIRING DIAGRAM

Scheme 2

Scheme 2: INSPECTION PROCEDURE
Scheme 2: INSPECTION PROCEDURE

Scheme 3

Scheme 3
Scheme 3
  1. CHECK HORN ASSEMBLY (OPERATION) Check if the horns sound normally. Result RESULT CHART Result Proceed to One horn does not sound A Both horns do not sound B HINT: If both horns do not sound, there may be a malfunction in the front light ECU. B: REPLACE FRONT LIGHT ECU A: Go to Next Step
  2. PERFORM ACTIVE TEST USING TECHSTREAM (VEHICLE HORNS) Operate the Techstream according to the steps on the display and select "Active Test". Body No. 5 BODY NO. 5 ACTIVE TEST REFERENCE Tester Display Test Part Control Range Horn Relay Operation Vehicle horns ON/OFF OK: Horn operates normally. NG: Go to step 3 OK: REPLACE FRONT LIGHT ECU
  3. INSPECT HORN ASSEMBLY Remove the horn for low pitched horn (see «REMOVAL» ) or high pitched horn (see «REMOVAL» ). Check operation of the horn. OK MEASUREMENT AND SPECIFIED CONDITION Measurement Condition Specified Condition Battery positive (+) --> Terminal 1 Battery negative (-) --> Horn bracket Horn sounds NG: REPLACE HORN ASSEMBLY OK: Go to Next Step
  4. CHECK HARNESS AND CONNECTOR (FRONT LIGHT ECU - HORN) Disconnect the B14 ECU connector. Disconnect the B6 or B10 horn connector. Measure the resistance according to the value(s) in the table below. Standard resistance for High pitched horn RESISTANCE SPECIFICATION Tester Connection Condition Specified Condition B14-2 (HORH) - B6-1 Always Below 1 ohms B14-2 (HORH) or B6-1 - Body ground Always 10 kohms or higher for Low pitched horn RESISTANCE SPECIFICATION Tester Connection Condition Specified Condition B14-1 (HORL) - B10-1 Always Below 1 ohms B14-1 (HORL) or B10-1 - Body ground Always 10 kohms or higher NG: REPAIR OR REPLACE HARNESS OR CONNECTOR OK: REPLACE FRONT LIGHT ECU

When the steering pad (horn button) is pressed, a signal is sent from the steering pad through the steering pad switch with modulator (steering pad ECU) to the spiral cable. The spiral cable and front light ECU (front controller) communicate via the CAN line. The front light ECU receives the signal and sends it to the vehicle horns, causing the horns to sound.

Scheme 4

Scheme 4: WIRING DIAGRAM
Scheme 4: WIRING DIAGRAM

Scheme 5

Scheme 5: INSPECTION PROCEDURE
Scheme 5: INSPECTION PROCEDURE

Scheme 6

Scheme 6
Scheme 6

Scheme 7

Scheme 7
Scheme 7
  1. CHECK FOR DTC Check for DTC (see «DTC CHECK/CLEAR» ). OK: DTC is not output. HINT: If DTC B2484 is output, troubleshoot it first. NG: GO TO «DTC CHART» OK: Go to Next Step
  2. READ VALUE USING TECHSTREAM (HORN BUTTON) Using the Techstream, read the DATA LIST. Steering Pad Switch STEERING PAD SWITCH DATA LIST REFERENCE Tester Display Measurement Item/Display (Range) Normal Condition Diagnostic Note Horn SW Horn button status/ON or OFF ON: Horn button is pressed OFF: Horn button is not pressed - OK: ON (horn button is pressed) appears on screen. NG: REPLACE STEERING PAD SWITCH ASSEMBLY WITH MODULATOR (See «REMOVAL» ) OK: Go to Next Step
  3. INSPECT HORN ASSEMBLY Remove the horn for low pitched horn (see «REMOVAL» ) or high pitched horn (see «REMOVAL» ). Check operation of the horn. OK MEASUREMENT AND SPECIFIED CONDITION Measurement Condition Specified Condition Battery positive (+) --> Terminal 1 Battery negative (-) --> Horn bracket Horn sounds NG: REPLACE HORN ASSEMBLY OK: Go to Next Step
  4. CHECK HARNESS AND CONNECTOR (FRONT LIGHT ECU - HORN) Disconnect the B14 ECU connector. Disconnect the B6 or B10 horn connector. Measure the resistance according to the value(s) in the table below. Standard resistance for High pitched horn RESISTANCE SPECIFICATION Tester Connection Condition Specified Condition B14-2 (HORH) - B6-1 Always Below 1 ohms B14-2 (HORH) or B6-1 - Body ground Always 10 kohms or higher for Low pitched horn RESISTANCE SPECIFICATION Tester Connection Condition Specified Condition B14-1 (HORL) - B10-1 Always Below 1 ohms B14-1 (HORL) or B10-1-Body ground Always 10 kohms or higher NG: REPAIR OR REPLACE HARNESS OR CONNECTOR OK: Go to Next Step
  5. INSPECT STEERING PAD Remove the steering pad (see «REMOVAL» ). Measure the resistance according to the value(s) in the table below. Standard resistance RESISTANCE SPECIFICATION Tester Connection Condition Specified Condition A-1 (HO) - B-1 Always Below 1 ohms NG: REPLACE STEERING PAD (See «REMOVAL» ) OK: Go to Next Step
  6. CHECK STEERING PAD SWITCH ASSEMBLY WITH MODULATOR (OPERATION) Temporarily replace the steering pad switch with modulator with a new or normally functioning one (see «REMOVAL» ). Check that the vehicle horns operate normally. OK: Vehicle horns operate normally. NG: REPLACE FRONT LIGHT ECU (FRONT CONTROLLER) OK: END (STEERING PAD SWITCH ASSEMBLY WITH MODULATOR IS FAULTY)

Scheme 8

Scheme 8: COMPONENTS
Scheme 8: COMPONENTS

Scheme 9

Scheme 9: REMOVAL
Scheme 9: REMOVAL
  1. REMOVE ENGINE ROOM SIDE COVER LH (See «REMOVAL» )
  2. REMOVE ENGINE ROOM SIDE COVER RH (See «REMOVAL» )
  3. REMOVE AIR CLEANER INLET COVER SUB-ASSEMBLY (See «REMOVAL»(/lexus/ls/iv-2006-2012/remont/testing-diagnostics/#engine-control-system) )
  4. REMOVE COOL AIR INTAKE DUCT SEAL (See «REMOVAL»(/lexus/ls/iv-2006-2012/remont/cooling-system-mechanical/#cooling) )
  5. REMOVE LOW PITCHED HORN ASSEMBLY Remove the bolt and horn. Disconnect the horn connector.

Scheme 10

Scheme 10: INSPECTION
Scheme 10: INSPECTION
  1. INSPECT LOW PITCHED HORN Apply battery voltage and check operation of the horn, as shown in the table. OK MEASUREMENT AND SPECIFIED CONDITION Measurement Condition Specified Condition Battery positive (+) --> Terminal 1 Battery negative (-) --> Body ground Horn sounds If the result is not as specified, replace the horn.

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