DESCRIPTION
When the theft deterrent system is switched from the armed state to the alarm sounding state, the main body ECU (multiplex network body ECU) transmits a signal to cause the security horn assembly to sound at intervals of 0.4 seconds.
WIRING DIAGRAM
CAUTION / NOTICE / HINT
NOTICE:
Click here
PROCEDURE
1. | PERFORM ACTIVE TEST USING TECHSTREAM (SECURITY HORN) |
(a) Connect the Techstream to the DLC3.
(b) Turn the engine switch on (IG).
(c) Turn the Techstream on.
(d) Enter the following menus: Body Electrical / Main Body / Active Test.
(e) Perform the Active Test according to the display on the Techstream.
Body Electrical > Main Body > Active Test Tester Display | Measurement Item | Control Range | Diagnostic Note |
---|---|---|---|
Security Horn | Security horn Assembly | OFF/ON | - |
Tester Display |
---|
Security Horn |
OK:
The security horn assembly sounds and stops correctly when operated through the Techstream.
OK | ![]() | REPLACE MAIN BODY ECU (MULTIPLEX NETWORK BODY ECU) |
|
2. | INSPECT SECURITY HORN ASSEMBLY |
(a) Remove the security horn assembly.
Click here
(b) Inspect the security horn assembly.
Click here
NG | ![]() | REPLACE SECURITY HORN ASSEMBLY |
|
3. | INSPECT S-HORN RELAY |
(a) Remove the S-HORN relay from the engine room relay block. |
|
(b) Measure the resistance according to the value(s) in the table below.
Standard Resistance:
Tester Connection | Condition | Specified Condition |
---|---|---|
3 - 5 | Battery voltage not applied between terminals 1 and 2 | 10 kΩ or higher |
3 - 5 | Battery voltage applied between terminals 1 and 2 | Below 1 Ω |
NG | ![]() | REPLACE S-HORN RELAY |
|
4. | INSPECT INSTRUMENT PANEL JUNCTION BLOCK ASSEMBLY |
(a) Remove the main body ECU (multiplex network body ECU).
Click here
*a | Component without harness connected (Instrument Panel Junction Block Assembly) | - | - |
(b) Disconnect the 2C instrument panel junction block assembly connector.
(c) Measure the resistance according to the value(s) in the table below.
Standard Resistance:
Tester Connection | Condition | Specified Condition |
---|---|---|
2C-26 - MB-29 (SH) | Always | Below 1 Ω |
NG | ![]() | REPLACE INSTRUMENT PANEL JUNCTION BLOCK ASSEMBLY |
|
5. | CHECK HARNESS AND CONNECTOR (BATTERY - S-HORN RELAY) |
(a) Measure the voltage according to the value(s) in the table below. Standard Voltage:
|
|
NG | ![]() | REPAIR OR REPLACE HARNESS OR CONNECTOR |
|
6. | CHECK HARNESS AND CONNECTOR (S-HORN RELAY - SECURITY HORN ASSEMBLY) |
(a) Measure the resistance according to the value(s) in the table below. Standard Resistance:
|
|
NG | ![]() | REPAIR OR REPLACE HARNESS OR CONNECTOR |
|
7. | CHECK HARNESS AND CONNECTOR (S-HORN RELAY - INSTRUMENT PANEL JUNCTION BLOCK ASSEMBLY) |
(a) Measure the resistance according to the value(s) in the table below. Standard Resistance:
|
|
OK | ![]() | REPLACE MAIN BODY ECU (MULTIPLEX NETWORK BODY ECU) |
NG | ![]() | REPAIR OR REPLACE HARNESS OR CONNECTOR |
Lexus RX (RX 350L, RX450h) 2016-2025 Repair Manual > Can Communication System: Main Body ECU Communication Stop Mode
DESCRIPTION Detection Item Symptom Trouble Area Main Body ECU Communication Stop Mode Either condition is met:
"Main Body" is not displayed on the CAN Bus Check screen of the Techstream.
Click here
Communication system DTCs (DTCs that start with U) that correspond to "Main Bod ...
Lexus RX (RX 350L, RX450h) 2016-2025 Repair Manual > Rear Power Seat Control System(for Second Row): Reclining Motor Circuit
DESCRIPTION HINT:
The rear power seat switch is a collective term for the rear power seat switch RH and the rear power seat switch LH.
The rear seatback frame sub-assembly is a collective term for the rear seatback frame sub-assembly RH and the rear seatback frame sub-assembly LH.
The fold s ...