INSPECTION PROCEDURE 2: The heated seat does not respond when the heated second seat switch is switched between HI and LO.
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Before replacing the ECU, ensure that the power supply circuit, the earth circuit and the communication circuit are normal.
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COMMENTS ON TROUBLE SYMPTOM
If the heated second seat does not respond when the heated second seat switch is switched between HI and LO, the respective switch or seat may be defective.
PROBABLE CAUSES
- Malfunction of the heated seat switch (second)
- Malfunction of the heated seat (second)
- Malfunction of the heated seat control unit
- Damaged wiring harness and connectors
DIAGNOSIS PROCEDURE
STEP 1. Determine a trouble spot
Q.
Which heated seat (second) does not work?
Left side
: Go to Step 2.
Right side : Go to Step 9.
STEP 2. Check the heated seat switch (second) (LH)
Refer to 
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Q.
Is the check result normal?
Go to Step 3.
Replace the heated seat switch (second) (LH).
STEP 3. Voltage measurement at heated seat switch (second) (LH) connector (LHSW line)
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(1)Disconnect the connector, and measure at the wiring harness side.
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(2)Turn the ignition switch to the LOCK (OFF) position.
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(3)Measure the voltage between the heated seat switch (second) (LH) connector (LHSW line) and the body earth.
OK: System voltage
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Q.
Is the check result normal?
Go to Step 5.
Go to Step 4.
STEP 4. Check of short to earth and open circuit in LHSW line between the heated seat control unit connector and the heated seat switch (second) (LH)connector
Q.
Is the check result normal?
Go to Step 5.
Repair the wiring harness.
STEP 5. Voltage measurement at heated seat (second) (LH) connector (HBRL line)
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(1)Disconnect the connector, and measure at the wiring harness side.
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(2)Turn the ignition switch to the LOCK (OFF) position.
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(3)Measure the voltage between the heated seat (second) (LH) connector HBRL line and HSRL line.
OK: System voltage
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Q.
Is the check result normal?
Go to Step 7.
Go to Step 6.
STEP 6. Check of short to earth and open circuit in HBRL, HSRL line between the heated seat control unit connector and the heated seat (second) (LH) connector
Q.
Is the check result normal?
Intermittent malfunction (Refer to GROUP 00 - How to Use Troubleshooting/Inspection Service Points - How to Cope with Intermittent Malfunction).
Repair the wiring harness.
STEP 7. Check the heated seat (second) (LH)
Refer to .
Q.
Is the check result normal?
Go to Step 8.
Replace the seat cushion heater or seat back heater (LH).
STEP 8. Retest the system
Does the heated second seat (left) respond when the heated second seat switch (left) is switched between HI and LO?
Q.
Is the check result normal?
Intermittent malfunction (Refer to GROUP 00 - How to Use Troubleshooting/Inspection Service Points - How to Cope with Intermittent Malfunction).
Replace the heated seat control unit.
STEP 9. Check the heated seat switch (second) (RH)
Refer to .
Q.
Is the check result normal?
Go to Step 10.
Replace the heated seat switch (second) (RH).
STEP 10. Voltage measurement at heated seat switch (second) (RH) connector (RHSW line)
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(1)Disconnect the connector, and measure at the wiring harness side.
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(2)Turn the ignition switch to the LOCK (OFF) position.
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(3)Measure the voltage between the heated seat switch (second) (RH) connector (RHSW line) and the body earth.
OK: System voltage
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Q.
Is the check result normal?
Go to Step 12.
Go to Step 11.
STEP 11. Check of short to earth and open circuit in RHSW line between the heated seat control unit connector and the heated seat switch (second) (RH) connector
Q.
Is the check result normal?
Go to Step 12.
Repair the wiring harness.
STEP 12. Voltage measurement at heated seat (second) (RH) connector (HBRR line)
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(1)Disconnect the connector, and measure at the wiring harness side.
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(2)Turn the ignition switch to the LOCK (OFF) position.
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(3)Measure the voltage between the heated seat (second) (RH) connector HBRR line and HSRR line.
OK: System voltage
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Q.
Is the check result normal?
Go to Step 14.
Go to Step 13.
STEP 13. Check of short to earth and open circuit in HBRR, HSRR line between the heated seat control unit connector and the heated seat (second) (RH) connector
Q.
Is the check result normal?
Intermittent malfunction (Refer to GROUP 00 - How to Use Troubleshooting/Inspection Service Points - How to Cope with Intermittent Malfunction).
Repair the wiring harness.
STEP 14. Check the heated seat (second) (RH)
Refer to .
Q.
Is the check result normal?
Go to Step 15.
Replace the seat cushion heater or seat back heater (RH).
STEP 15. Retest the system
Does the heated second seat (right) respond when the heated second seat switch (right) is switched between HI and LO?
Q.
Is the check result normal?
Intermittent malfunction (Refer to GROUP 00 - How to Use Troubleshooting/Inspection Service Points - How to Cope with Intermittent Malfunction).
Replace the heated seat control unit.