Toyota Avalon (XX50): Heated Steering Wheel System(for Hv Model)

How To Proceed With Troubleshooting

CAUTION / NOTICE / HINT

HINT:

Use these procedures to troubleshoot the heated steering wheel system.

PROCEDURE

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(a) Measure the auxiliary battery voltage with the power switch off.

Standard voltage:

11 to 14 V (Power switch off)

If the voltage is below 11 V, replace or recharge the auxiliary battery before proceeding to the next step.

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HINT:

Refer to Problem Symptoms Table.

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Parts Location

PARTS LOCATION

ILLUSTRATION

Precaution

PRECAUTION

PRECAUTION FOR DISCONNECTING CABLE FROM NEGATIVE AUXILIARY BATTERY TERMINAL

NOTICE:

When disconnecting the cable from the negative (-) auxiliary battery terminal, initialize the following system(s) after the cable is reconnected:

HANDLING PRECAUTIONS FOR SRS AIRBAG SYSTEM

(a) This vehicle is equipped with a Supplemental Restraint System (SRS). Failure to carry out service operations in the correct sequence could cause the SRS to unexpectedly deploy during servicing. This may cause a serious accident.

Before servicing (including inspection, replacement, removal and installation of parts), be sure to read the precautionary notices for Supplemental Restraint System.

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Problem Symptoms Table

PROBLEM SYMPTOMS TABLE

HINT:

Use the table below to help determine the cause of problem symptoms. If multiple suspected areas are listed, the potential causes of the symptoms are listed in order of probability in the "Suspected Area" column of the table. Check each symptom by checking the suspected areas in the order they are listed. Replace parts as necessary.

System Description

SYSTEM DESCRIPTION

HEATED STEERING WHEEL SYSTEM

(a) The steering heater warms up the steering wheel when the steering heater switch is turned on.

(b) The steering heater uses a control thermostat inside the steering wheel to maintain the steering wheel at the specified temperature.

OPERATION DESCRIPTION

(a) When the steering heater switch is turned on with the power switch on (IG), the heater indicator light illuminates and the heater inside the steering wheel operates. If the steering heater switch is pushed again, the heater indicator light turns off and the heater stops operating.

(b) A control thermostat and an additional thermostat used as a safety device to prevent overheating are installed inside the steering wheel.

CONTROL DESCRIPTION

(a) When the steering heater switch is turned on, current flows to the LO and HI sides, starting the warming operation to warm the steering wheel.

(b) When the temperature of the steering wheel reaches the operation temperature of the control thermostat, the control thermostat stops the flow of current to the HI side, only allowing current to flow to the LO side and thereby maintaining the temperature of the steering wheel.

(c) While operating to maintain the temperature of the steering wheel, if the temperature drops to the operation temperature of the control thermostat, the control thermostat restarts the flow of current to both the LO and HI sides to warm the steering wheel.

(d) While the steering heater switch is on, the control thermostat automatically stops and restarts the flow of current to the HI side according to the temperature of the steering wheel, continuously maintaining the specified temperature.

(e) If a malfunction occurs in the steering heater circuit and the temperature exceeds the specified temperature, the overheating prevention thermostat stops the flow of current to the circuit, the heater indicator light turns off and the heater stops operating.

System Diagram

SYSTEM DIAGRAM

SYSTEM DIAGRAM