Lexus NX: System Description
SYSTEM DESCRIPTION
HEATED STEERING WHEEL SYSTEM
(a) The heated steering wheel system heats the steering wheel assembly when the steering heater switch is operated.
(b) The heated steering wheel system uses a thermistor inside of the steering wheel assembly to detect the heater temperature and maintain the set temperature.
(c) The heated steering wheel timer function turns off the heater after a predetermined period of time.
HEATER CONTROLLER SYSTEM
(a) Operation description
(1) When the power switch is on (IG), pressing the steering heater switch illuminates the LED and current is output from the steering vibration and heater ECU to the steering wheel heater unit of the heated steering wheel system. Pressing the steering heater switch again turns off the LED and stops the current from being output.
(2) A thermostat is installed in the steering wheel heater unit as a safety mechanism.
(3) The steering heater switch LED will go off when either of the following occurs: 1) an open or short in the steering wheel heater unit thermistor continues for 2 seconds or more; or 2) the steering heater switch is pressed continuously for 10 seconds or more.
(4) If the normal condition is restored for 2 seconds or more, the previous operation before the malfunction occurred continues. However, regardless of if a malfunction is detected and the malfunction operation is occurring, and regardless of if the normal condition is restored and the system is operating normally, the timer will turn off the heater 30 minutes after the steering heater switch was first turned on.
(b) Signal input / output description
| Signal | Signal Name | Function |
|---|---|---|
| Input | Thermistor input | Input of voltage corresponding to heater temperature |
| Input | Operating switch input | Input of power circuit operation estimate signal |
| Output | LED output | Output of LED |
| Output | Drive current output | Output of drive current |
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How To Proceed With Troubleshooting
CAUTION / NOTICE / HINT HINT: Use these procedures to troubleshoot the heated steering wheel system. PROCEDURE 1. VEHICLE BROUGHT TO WORKSHOP
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TERMINALS OF ECU HINT: Perform the inspection from the harness side with the connectors connected. STEERING HEATER AND VIBRATION ECU (a) Measure the voltage or resistance according to the value(s) in
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