Theft Deterrent: Overview Lexus LS IV

SYSTEM DESCRIPTION

1. THEFT DETERRENT SYSTEM DESCRIPTION The theft deterrent system is designed to deter vehicle break-ins and theft. If an attempted break-in or theft is detected, the vehicle horns and security horn will sound, the headlights, taillights and room light will illuminate and the hazard warning light will flash. The system detects an attempted break-in or theft when any of the following occurs: 1) the vehicle is forcibly entered; 2) the engine hood is forcibly opened; 3) the doors are unlocked without the use of a key; or 4) the cable from the negative (-) battery terminal is disconnected and reconnected. If the system enters the alarm sounding state, any unlocked doors will automatically lock. The system has 4 states: disarmed state, arming preparation state, armed and alarm sounding state.
2. FUNCTION OF MAIN COMPONENT FUNCTION OF MAIN COMPONENT Function Outline Security indicator Informs driver of theft deterrent system status Security horn Sounds when attempted brake-in or theft is detected Taillight Taillight illuminates if system enters alarm sounding state when system is unset Hazard warning light Hazard warning light begins flashing when attempted break-in or theft is detected Vehicle horns Sounds when attempted break-in or theft is detected Door courtesy light switch Detects door open status (open or closed) Door lock position switch Detects door lock status (locked or unlocked) Engine hood courtesy switch Detects engine hood open status (open or closed) Luggage compartment door courtesy switch Detects luggage compartment door open status (open or closed) Main body ECU Detects engine switch condition (off, on (ACC, IG) or engine running)
3. SYSTEM FUNCTION Disarmed state: The alarm function is not operating. The theft deterrent system is not operating. Arming preparation state: The theft deterrent system is not operating. Arming state: The theft deterrent system is operating. Alarm sounding state: The alarm function is operating (60 +1-5 seconds).

DESCRIPTION

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

DTC DETECTION CONDITION CHART

Scheme 286

Scheme 287

Scheme 288

1. PERFORM ACTIVE TEST USING TECHSTREAM (SECURITY HORN) Operate the Techstream according to the steps on the display and select "Active Test". Body No. 5 TESTER DISPLAY REFERENCE Tester Display Test Part Control Range Security Horn Security horn ON/OFF OK: Security horn operates normally. NG: Go to step 2 OK: REPLACE FRONT LIGHT ECU
2. INSPECT SECURITY HORN ASSEMBLY Remove the security horn (see «REMOVAL» ). Check operation of the horn. OK MEASUREMENT CONDITION CHART Measurement Condition Specified Condition Battery positive (+) --> Terminal 1 Battery negative (-) --> Horn bracket Horn sounds NG: REPLACE SECURITY HORN ASSEMBLY (See «REMOVAL» ) OK: Go to Next Step
3. CHECK HARNESS AND CONNECTOR (FRONT LIGHT ECU - SECURITY HORN) Disconnect the A52 ECU connector. Disconnect the A29 horn connector. Measure the resistance according to the value(s) in the table below. Standard resistance TESTER CONNECTION SPECIFIED CONDITION CHART Tester Connection Condition Specified Condition A52-4 (SH-) - A29-1 Always Below 1 ohms A52-4 (SH-) or A29-1 - Body ground Always 10 kohms or higher NG: REPAIR OR REPLACE HARNESS OR CONNECTOR OK: REPLACE FRONT LIGHT ECU

The engine hood courtesy switch is built into the hood lock. This switch turns on when the engine hood is opened and turns off when the engine hood is closed.

Scheme 289

Scheme 290

Scheme 291

1. READ VALUE USING TECHSTREAM (ENGINE HOOD COURTESY SWITCH) Using the Techstream, read the Data List. Body No. 5 DIAGNOSTIC NOTE Tester Display Measurement Item/Display (Range) Normal Condition Diagnostic Note Hood Courtesy Switch Engine hood courtesy switch/ON or OFF ON: Engine hood is open OFF: Engine hood is closed - OK: ON (engine hood is open) appears on screen. NG: Go to step 2 OK: REPLACE FRONT LIGHT ECU (FRONT CONTROLLER)
2. INSPECT HOOD LOCK ASSEMBLY (ENGINE HOOD COURTESY SWITCH) Remove the hood lock (see «REMOVAL» ). Measure the resistance according to the value(s) in the table below. Standard resistance TESTER CONNECTION SPECIFIED CONDITION CHART Tester Connection Switch Condition Specified Condition 1-2 UNLOCK position Below 1 ohms 1-2 LOCK position 10 kohms or higher NG: REPLACE HOOD LOCK ASSEMBLY (ENGINE HOOD COURTESY SWITCH) (See «REMOVAL» ) OK: Go to Next Step
3. CHECK HARNESS AND CONNECTOR (FRONT LIGHT ECU GROUND) Disconnect the B14 ECU connector. Disconnect the B7 switch connector. Measure the resistance according to the value(s) in the table below. Standard resistance TESTER CONNECTION SPECIFIED CONDITION CHART Tester Connection Condition Specified Condition B14-21 (HDCY) - B7-2 Always Below 1 ohms B7-1 - Body ground Always Below 1 ohms B14-21 (HDCY) or B7-2 - Body ground Always 10 kohms or higher NG: REPAIR OR REPLACE HARNESS OR CONNECTOR OK: REPLACE FRONT LIGHT ECU (FRONT CONTROLLER)

When the theft deterrent system is in the disarmed state, the security indicator will flash continuously if the immobilizer system is set, or not illuminate if the immobilizer system is not set.

When the theft deterrent system is in the armed state, the immobilizer system is automatically set and the security indicator will flash continuously.

When the theft deterrent system is in the arming preparation state and alarm sounding state, the certification ECU causes the security indicator to be illuminated.

Scheme 292

Scheme 293

Scheme 294

Scheme 295

Scheme 296

1. CHECK INDICATOR LIGHT ASSEMBLY Check if the security indicator lights are normal. Result RESULT CHART Result Proceed to One security indicator light is malfunctioning A Both security indicator lights are malfunctioning B HINT: If both security indicator lights are malfunctioning, there may be a malfunction in the certification ECU. B: REPLACE CERTIFICATION ECU A: Go to Next Step
2. PERFORM ACTIVE TEST USING TECHSTREAM (SECURITY INDICATOR) Operate the Techstream according to the steps on the display and select "Active Test". Smart Access TESTER DISPLAY REFERENCE Tester Display Test Part Control Range Security Indicator Security indicator ON/OFF OK: Security indicator illuminates. NG: Go to step 3 OK: REPLACE CERTIFICATION ECU
3. CHECK HARNESS AND CONNECTOR (DOOR ECU - SECURITY INDICATOR) Disconnect the P10*1 or P4*2 ECU connector. Disconnect the P9*1 or P3*2 indicator connector. Measure the resistance according to the value(s) in the table below. Standard resistance for LH TESTER CONNECTION SPECIFIED CONDITION CHART Tester Connection Condition Specified Condition P10-8 (SID+) - P9-2 (LP2) Always Below 1 ohms P10-9 (SID-) - P9-1 (E2) Always Below 1 ohms P10-8 (SID+) or P9-2 (LP2) - Body ground Always 10 kohms or higher P10-9 (SID-) or P9-1 (E2) - Body ground Always 10 kohms or higher for RH TESTER CONNECTION SPECIFIED CONDITION CHART Tester Connection Condition Specified Condition P4-8 (SID+) - P3-2 (LP1) Always Below 1 ohms P4-9 (SID-) - P3-1 (E1) Always Below 1 ohms P4-8 (SID+) or P3-2 (LP1) - Body ground Always 10 kohms or higher P4-9 (SID-) or P3-1 (E1) - Body ground Always 10 kohms or higher NG: REPAIR OR REPLACE HARNESS OR CONNECTOR OK: Go to Next Step
4. CHECK HARNESS AND CONNECTOR (DOOR ECU - CERTIFICATION ECU AND BODY GROUND) Disconnect the N10*1 or N 1*2 ECU connector. Disconnect the L15 ECU connector. Measure the resistance according to the value(s) in the table below. Standard resistance for LH TESTER CONNECTION SPECIFIED CONDITION CHART Tester Connection Condition Specified Condition N10-23 (SID1) - L15-2 (IND) Always Below 1 ohms N10-1 (GND) - Body ground Always Below 1 ohms N10-23 (SID1) or L15-2 (IND) - Body ground Always 10 kohms or higher for RH TESTER CONNECTION SPECIFIED CONDITION CHART Tester Connection Condition Specified Condition N1-23 (SID1) - L15-2 (IND) Always Below 1 ohms N1-1 (GND) - Body ground Always Below 1 ohms N1-23 (SID1) or L15-2 (IND) - Body ground Always 10 kohms or higher NG: REPAIR OR REPLACE HARNESS OR CONNECTOR OK: Go to Next Step
5. INSPECT INDICATOR LIGHT ASSEMBLY Remove the indicator light (see «REMOVAL» ). Check operation of the indicator light. OK MEASUREMENT CONDITION CHART Measurement Condition Specified Condition Battery positive (+) --> Terminal 2 (LP2*1, LP1*2) Battery positive (+) --> Terminal 1 (E*1, E1*2) Illuminates HINT: *1: for LH *2: for RH NOTE: If the positive (+) lead and the negative (-) lead are incorrectly connected, the security indicator will not turn on. A voltage of more than 12 V will damage the security indicator. If the voltage is too low, the security indicator will not turn on. NG: REPLACE INDICATOR LIGHT ASSEMBLY (See «REMOVAL» ) OK: Go to Next Step
6. CHECK FRONT DOOR ECU (OPERATION) Temporarily replace the front door ECU with a new or normally functioning one (see «REMOVAL» ). Check that the security indicator operates normally. OK: Security indicator operates normally. NG: REPLACE CERTIFICATION ECU OK: REPLACE FRONT DOOR ECU (See «REMOVAL» )

This circuit provides power to operate the certification ECU.

Scheme 297

Scheme 298

1. INSPECT FUSE (SECURITY) Remove the SECURITY fuse from the main body ECU. Measure the resistance of the fuse. Standard resistance TESTER CONNECTION SPECIFIED CONDITION CHART Tester Connection Condition Specified Condition SECURITY fuse Always Below 1 ohms NG: REPLACE FUSE OK: Go to Next Step
2. CHECK HARNESS AND CONNECTOR (CERTIFICATION ECU - BATTERY AND BODY GROUND) Disconnect the L15 ECU connector. Measure the resistance according to the value(s) in the table below. Standard resistance TESTER CONNECTION SPECIFIED CONDITION CHART Tester Connection Condition Specified Condition L15-17(E) - Body ground Always Below 1 ohms Standard voltage TESTER CONNECTION SPECIFIED CONDITION CHART Tester Connection Condition Specified Condition L15-1 (+B1) - Body ground Always 11 to 14 V NG: REPAIR OR REPLACE HARNESS OR CONNECTOR OK: PROCEED TO NEXT CIRCUIT INSPECTION SHOWN IN PROBLEM SYMPTOMS TABLE (See «PROBLEM SYMPTOMS TABLE» )

When the engine switch is turned on (IG), positive (+) battery voltage is applied to the certification ECU.

Scheme 299

Scheme 300

1. CHECK BASIC FUNCTION (PUSH-BUTTON START FUNCTION) Check the basic function of the push-button start function. OK: Basic function operates normally. NG: GO TO SMART ACCESS SYSTEM WITH PUSH-BUTTON START (for Starting) (See «HOW TO PROCEED WITH TROUBLESHOOTING» ) OK: Go to Next Step
2. INSPECT FUSE (P IG2) Remove the P IG2 fuse from the passenger side junction block. Measure the resistance of the fuse. Standard resistance TESTER CONNECTION SPECIFIED CONDITION CHART Tester connection Condition Specified Condition P IG2 fuse Always Below 1 ohms NG: REPLACE FUSE OK: Go to Next Step
3. CHECK HARNESS AND CONNECTOR (CERTIFICATION ECU - BATTERY) Disconnect the L15 ECU connector. Measure the resistance and voltage according to the value(s) in the table below. Standard resistance TESTER CONNECTION SPECIFIED CONDITION CHART Tester Connection Condition Specified Condition L15-17 (E) - Body ground Always Below 1 ohms Standard voltage TESTER CONNECTION SPECIFIED CONDITION CHART Tester Connection Switch Condition Specified Condition L15-18 (IG) - Body ground Engine switch on (IG) 11 to 14 V NG: REPAIR OR REPLACE HARNESS OR CONNECTOR OK: PROCEED TO NEXT CIRCUIT INSPECTION SHOWN IN PROBLEM SYMPTOMS TABLE (See «PROBLEM SYMPTOMS TABLE» )

Scheme 301

Scheme 302

See also:
• CAN COMMUNICATION SYSTEM
• REMOVAL
• REMOVAL