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
| • | The BCM detects that the change in voltage of the temperature sensor signal circuit is either too fast or too slow. |
| • | The BCM performs the slow rate check only when the heated seat is initially turned ON in order to prevent setting a false DTC. |
| • | 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
The numbers below refer to the step numbers on the diagnostic table.
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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.
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This test determines the functionality of the heated seat relay.
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This test verifies the repair.
Step | Action | Value(s) | Yes | No |
|---|---|---|---|---|
Schematic Reference: Driver Seat Schematics or Passenger Seat Schematics Connector End View Reference: Power Seat Connector End Views | ||||
1 | Did you perform the Diagnostic System Check - Vehicle? | -- | Go to Step 2 | |
Does the test lamp illuminate? | -- | Go to Step 4 | Go to Step 3 | |
Does the test lamp illuminate? | -- | Go to Step 13 | Go to Step 18 | |
4 |
Does the resistance measure less than the specified value? | 5 ohms | Go to Step 7 | Go to Step 5 |
5 |
Does the resistance measure less than the specified value? | 5 ohms | Go to Step 6 | Go to Step 14 |
6 |
Does the resistance measure less than the specified value? | 5 ohms | Go to Step 10 | Go to Step 15 |
7 |
Important: If the resistance is measured with the seat still warm, the resistance may vary outside of the specified range since the thermistor resistance varies with temperature.
Does the resistance measure within the specified range? | 535-168,000 ohms | Go to Step 12 | Go to Step 8 |
8 | Test the heated seat temperature sensor signal circuit and the temperature sensor low reference circuit, between the BCM and the temperature sensor, for a short to ground or an open. Refer to Circuit Testing and Wiring Repairs . Did you find and correct the condition? | -- | Go to Step 22 | Go to Step 9 |
9 | Test the heated seat temperature sensor signal circuit, between the BCM, and the temperature sensor for a short to battery positive voltage. Refer to Circuit Testing and Wiring Repairs . Did you find and correct the condition? | -- | Go to Step 22 | Go to Step 14 |
10 | Test the heated seat element supply voltage circuit between the heated seat relay and the seat cushion heating element for an open. Refer to Circuit Testing and Wiring Repairs . Did you find and correct the condition? | -- | Go to Step 22 | Go to Step 11 |
11 | Test the heated seat element supply voltage circuit between the seat cushion heating element and the seat back heating element for an open. Refer to Circuit Testing and Wiring Repairs . Did you find and correct the condition? | -- | Go to Step 22 | Go to Step 17 |
12 | Test the heated seat element supply voltage circuit between the seat cushion heating element and the seat back heating element for a short to ground. Refer to Circuit Testing and Wiring Repairs . Did you find and correct the condition? | -- | Go to Step 22 | Go to Step 16 |
13 | Inspect for poor connections at the harness connector of the heated seat relay. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs . Did you find and correct the condition? | -- | Go to Step 22 | Go to Step 19 |
14 | Inspect for poor connections at the harness connector of the heated seat cushion heating element/temperature sensor. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs . Did you find and correct the condition? | -- | Go to Step 22 | Go to Step 20 |
15 | Inspect for poor connections at the harness connector of the heated seat back heating element. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs . Did you find and correct the condition? | -- | Go to Step 22 | Go to Step 20 |
16 | Inspect for poor connections at the harness connector of the BCM. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs . Did you find and correct the condition? | -- | Go to Step 22 | Go to Step 21 |
17 | Repair the open in the ground circuit of the seat heating elements. Refer to Wiring Repairs . Did you complete the repair? | -- | Go to Step 22 | -- |
18 | Repair the short to ground or open in the battery positive voltage circuit of the heated seat relay. Refer to Wiring Repairs . Did you complete the repair? | -- | Go to Step 22 | -- |
19 | Replace the heated seat relay. Refer to Relay Replacement . Did you complete the replacement? | -- | Go to Step 22 | -- |
20 | Replace the heated seat cushion heating element/temperature sensor or seat back heating element. Refer to Driver or Passenger Seat Back Cushion Heater Replacement and Driver or Passenger Seat Cushion Heater Replacement . Did you complete the replacement? | -- | Go to Step 22 | -- |
21 | Replace the BCM. Refer to Control Module References for replacement, setup, and programming. Did you complete the replacement? | -- | Go to Step 22 | -- |
Does the DTC reset? | -- | Go to Step 2 | System OK | |
