B1920

DTC B1920

CIRCUIT DESCRIPTION
The heated seat temperature sensor that set this DTC is located in the seat cushion just under the seat cover with the seat heating element. The body control module (BCM) supplies a 10-volt signal and a low reference circuit to the sensor. The BCM monitors the voltage of the heated seat temperature sensor signal circuit to determine the temperature of the seat. The BCM will then cycle the heated seat relay ON and OFF in order to maintain the desired seat temperature based on the voltage feedback from the temperature sensor.

The BCM also monitors the sensor signal circuit for a change in voltage that is either too fast or too slow. The slow rate check is performed only when the heated seat is initially turned ON with a cold seat in order to prevent setting a false DTC.

DTC DESCRIPTORs
This diagnostic procedure supports the following DTCs:
- DTC B1920 Seat Heater Timer Circuit
- DTC B2165 Seat Heater Timer Circuit

CONDITIONS FOR RUNNING THE DTC
- The BCM must be powered and cannot have B1327, Battery Voltage Low, as an active DTC for this DTC to set.
- The module voltage must be 9-16 volts.
- The heated seat system is active.

CONDITIONS FOR SETTING THE DTC
1. The BCM detects that the change in voltage of the temperature sensor signal circuit is either too fast or too slow.
2. The BCM performs the slow rate check only when the heated seat is initially turned on in order to prevent setting a false DTC.
3. The slow rate check may take the BCM 10 minutes to set a DTC.

ACTION TAKEN WHEN THE DTC SETS
- The BCM will turn OFF the heated seat operation.
- Current and history codes are stored.

CONDITIONS FOR CLEARING THE DTC
The current DTC will clear whenever the diagnostic feedback to the BCM indicates that the fault no longer exists.

DIAGNOSTIC AIDS
- Because the BCM takes approximately 10 minutes to set this DTC, the tests in this diagnostic table are performed without the DTC being active.
- Faults in circuits of the heated seat system other than the temperature sensor may cause this DTC to set.

TEST DESCRIPTION

Steps 1 - 9:

Steps 10 - 22:

The numbers below refer to the step numbers on the diagnostic table.
2. If an active DTC is set, the BCM will turn OFF the heated seat relay, not allowing for an accurate test of the relay. By cycling the ignition switch, the BCM turns OFF the active DTC allowing for an accurate test.
3. This test determines the functionality of the heated seat relay.
22. This test verifies the repair.