Circuit Description
The driver seat module relies on inputs from thermistors installed in the driver and passenger seat backs to control heated seat temperatures. The thermistors are 2-wire sensors supplied with a 5-volt referenced signal circuit and low reference circuit from the driver seat module. Resistance through the thermistors varies with temperature causing the heated seat sensor signal circuit voltage levels to decrease as the seat back temperatures rise.
DTC Descriptors
This diagnostic procedure supports the following DTCs:
| • | DTC B2435 Driver Seat Back Heater Sensor Circuit |
| • | DTC B2440 Passenger Seat Back Heater Sensor Circuit |
Conditions for Running the DTC
| • | The system voltage must be between 9-16 volts. |
| • | The heated seat is in an active state. |
Conditions for Setting the DTC
| • | The heated seat sensor signal circuit voltage to the driver seat module is greater than 4.94 volts for 30 seconds or more. |
| • | The heated seat sensor signal circuit voltage to the driver seat module is less than 0.078 volts for 30 seconds or more. |
| • | The heated seat sensor signal circuit input to the driver seat module indicates that the desired seat temperature has not been reached within 30 minutes after activation. |
Action Taken When the DTC Sets
| • | The heated seat with a current status DTC will be disabled. |
| • | When the fault is no longer present a history status DTC will be stored, and heated seat operation will be restored. |
Conditions for Clearing the DTC
| • | The DTC will be current for as long as the fault is present. |
| • | When the fault is no longer present the DTC will be a history status code. |
| • | The history DTC will be cleared after 100 error free ignition cycles, or by using the scan tool clearing DTCs feature. |
Test Description
The numbers below refer to the step numbers on the diagnostic table.
-
Tests for the proper operation of the circuit in the high voltage range.
-
Tests for the proper operation of the circuit in the low voltage range. If the fuse in the jumper opens upon performing this test, the signal circuit has a short to voltage.
Step | Action | Values | Yes | No | ||||||
|---|---|---|---|---|---|---|---|---|---|---|
Schematic Reference: Driver Seat Schematics and 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 | Go to Diagnostic System Check - Vehicle in Vehicle DTC Information | ||||||
2 |
Does the scan tool indicate that the Heated Seat Sensor parameter is within the specified range? | 0.078-4.94 V | Go to Testing for Intermittent Conditions and Poor Connections in Wiring Systems | Go to Step 3 | ||||||
Is the Heated Seat Sensor parameter greater than the specified value? | 4.5 V | Go to Step 4 | Go to Step 5 | |||||||
Is the Heated Seat Sensor parameter less than the specified value? | 0.5 V | Go to Step 8 | Go to Step 6 | |||||||
5 | Test the signal circuit of the heated seat sensor for a short to ground. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 12 | Go to Step 9 | ||||||
6 | Test the signal circuit of the heated seat sensor for one of the following conditions:
Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 12 | Go to Step 7 | ||||||
7 | Test the low reference circuit of the heated seat sensor for one of the following conditions:
Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 12 | Go to Step 9 | ||||||
8 | Inspect for poor connections at the harness connector of the heated seat sensor. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 12 | Go to Step 10 | ||||||
9 | Inspect for poor connections at the harness connectors of the driver seat module. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 12 | Go to Step 11 | ||||||
10 | Replace the seat back heater element. Did you complete the replacement? | -- | Go to Step 12 | -- | ||||||
11 | Replace the driver seat module. Refer to Control Module References in Computer/Integrating Systems for replacement, setup, and programming. Did you complete the replacement? | -- | Go to Step 12 | -- | ||||||
12 |
Does the DTC reset? | -- | Go to Step 2 | System OK | ||||||
