GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Chevrolet 🢒 2009 🢒 Tahoe - 4WD 🢒 DTC 🢒 DTC B1935 or B2180

DTC B1935 or B2180 With Memory, Without HP2

Diagnostic Instructions
    • Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.
    • Review Strategy Based Diagnosis for an overview of the diagnostic approach.
    •  Diagnostic Procedure Instructions provides an overview of each diagnostic category.

DTC Descriptors

DTC B1935 04: Left Seat Back Heater Circuit Open

DTC B1935 0A: Left Seat Back Heater Circuit Rate of Change Below Threshold

DTC B1935 0B: Left Seat Back Heater Circuit Current Above Threshold

DTC B1935 0C: Left Seat Back Heater Circuit Current Below Threshold

DTC B1935 0D: Left Seat Back Heater Circuit Resistance Above Threshold

DTC B1935 0E: Left Seat Back Heater Circuit Resistance Below Threshold

DTC B1935 1F: Left Seat Back Heater Circuit Intermittent

DTC B2180 04: Right Seat Back Heater Circuit Open

DTC B2180 0A: Right Seat Back Heater Circuit Rate of Change Below Threshold

DTC B2180 0B: Right Seat Back Heater Circuit Current Above Threshold

DTC B2180 0C: Right Seat Back Heater Circuit Current Below Threshold

DTC B2180 0D: Right Seat Back Heater Circuit Resistance Above Threshold

DTC B2180 0E: Right Seat Back Heater Circuit Resistance Below Threshold

DTC B2180 1F: Right Seat Back Heater Circuit Intermittent

Diagnostic Fault Information

Circuit

Short to Ground

Open/High Resistance

Short to Voltage

Signal Performance

B+ MSM Terminal 5 X3

1, 2, B1935 0C, B1935 0D, B2180 0C, B2180 0D, B2425 0C, B2425 0D, B2430 0C, B2430 0D

1, 2, B1935 0C, B1935 0D, B2180 0C, B2180 0D, B2425 0C, B2425 0D, B2430 0C, B2430 0D

--

--

Driver Heated Seat Back Element Supply Voltage

B2508 02

B1935 0C, B1935 0D

B2345 00, B2508 01

B1935 0B, B1935 0E

Driver Heated Seat Back Element Control

B2345 00, B2508 02

B1935 0C, B1935 0D

B2345 00, B2508 01

B1935 0B, B1935 0E

Driver Heated Seat Back Temperature Sensor Signal

B2435 02

B1935 04, B1935 1F, B2435 0D

B1935 04, B1935 1F, B2435 0D

B1935 0A, B2345 13, B2345 42, B2345 4B

Driver Heated Seat Back Temperature Sensor Low Reference

--

B1935 04, B1935 1F, B2435 0D

--

B2345 13, B2345 42, B2345 4B

Driver Heated Seat Cushion Element Supply Voltage

B2508 02

B2425 0C, B2425 0D

B2345 00, B2508 01

B2425 0B, B2425 0E

Driver Heated Seat Cushion Element Control

B2345 00, B2508 02

B2425 0C, B2425 0D

B2345 00, B2508 01

B2425 0B, B2425 0E

Driver Heated Seat Cushion Temperature Sensor Signal

B1925 02, B2425 1F

B1925 05, B2425 04, B2425 1F

B1925 05, B2425 04, B2425 1F

B2345 13, B2345 42, B2345 4B, B2425 0A

Driver Heated Seat Cushion Temperature Sensor Low Reference

--

B1925 05, B2425 04, B2425 1F

--

B2345 13, B2345 42, B2345 4B

Passenger Heated Seat Back Element Supply Voltage

B2508 02

B2180 0C, B2180 0D

B2345 00, B2508 01

B2180 0B, B2180 0E

Passenger Heated Seat Back Element Control

B2345 00, B2508 02

B2180 0C, B2180 0D

B2345 00, B2508 01

B2180 0B, B2180 0E

Passenger Heated Seat Back Temperature Sensor Signal

B2440 02

B2180 04, B2180 1F, B2440 05

B2180 04, B2180 1F, B2440 05

B2180 0A, B2345 13, B2345 42, B2345 4B

Passenger Heated Seat Back Temperature Sensor Low Reference

--

B2180 04, B2180 1F, B2440 05

--

B2345 13, B2345 42, B2345 4B

Passenger Heated Seat Cushion Element Supply Voltage

B2508 02

B2430 0C, B2430 0D

B2345 00, B2508 01

B2430 0B, B2430 0E

Passenger Heated Seat Cushion Element Control

B2345 00, B2508 02

B2430 0C, B2430 0D

B2345 00, B2508 01

B2430 0B, B2430 0E

Passenger Heated Seat Cushion Temperature Sensor Signal

B2170 02, B2430 1F

B2430 04, B2430 1F, B2170 05

B2430 04, B2430 1F, B2170 05

B2345 13, B2345 42, B2345 4B, B2430 0A

Passenger Heated Seat Cushion Temperature Sensor Low Reference

--

B2430 04, B2430 1F, B2170 05

--

B2345 13, B2345 42, B2345 4B

1. Power seat inoperative

2. Heated seat inoperative

Circuit/System Description

When the heated seat function is active, the memory seat module (MSM) supplies battery voltage through the element supply voltage circuit to the seat heater elements. The module controls the seat temperature by providing a PWM ground through the heated seat element control circuit to the seat heater elements. The module then monitors the current flow through the heating element and the temperature sensor rate of change to verify correct operation.

Conditions for Running the DTC

The MSM must be powered and the heated seat must be enabled.

Conditions for Setting the DTC

B1935 04, B2180 04

The module does not detect a temperature change within 210 seconds.

B1935 0A, B2180 0A

The module detects that the set point temperature has not been reached within 8.5 minutes.

B1935 0B, B1935 0E, B2180 0B, B2180 0E

By measuring output current, the module calculates that the heating element resistance is below the minimum resistance.

B1935 0C, B1935 0D, B2180 0C, B2180 0D

By measuring output current, the module calculates that the heating element resistance is above the maximum resistance.

B1935 1F, B2180 1F

The temperature sensor voltage is erratic or changes suddenly.

Action Taken When the DTC Sets

The heated seat back function for the affected seat will be disabled.

Conditions for Clearing the DTC
    • The current DTC clears when the malfunction is no longer present and the power mode changes to OFF then back to ACC or RUN.
    • The history DTC will clear after 50 consecutive fault-free ignition cycles have occurred.

Reference Information

Schematic Reference

Heated/Cooled Seat Schematics

Connector End View Reference

Component Connector End Views

Description and Operation

Heated Seats Description and Operation

Electrical Information Reference

    •  Circuit Testing
    •  Connector Repairs
    •  Testing for Intermittent Conditions and Poor Connections
    •  Wiring Repairs

Scan Tool Reference

Control Module References for scan tool information

Circuit/System Testing

B1935 0A, B1935 0B, B1935 0C, B1935 0D, B1935 0E, B1935 04, or B1935 1F

  1. Ignition OFF, disconnect the X3 harness connector at the MSM.
  2. Ignition ON, verify that a test lamp illuminates between the B+ circuit terminal 5 and ground.
    3. ⇒If the test lamp does not illuminate, test the B+ circuit for a short to ground or an open/high resistance.
  3. Ignition OFF, connect the X3 harness connector at the MSM and disconnect the X1 harness connector at the MSM.

    4. Important: When measuring the resistance, the resistance values are based on the seat being at room temperature of 20°C (68°F).

  4. Test for 3.5-11.5 ohms between control circuit terminal 14 and control circuit terminal 1.
    5. ⇒If greater than the specified range, test the control circuits for an open/high resistance. If the circuits test normal, replace the seat back heater element.
    ⇒If less than the specified range, test for a short between the control circuits. If the circuits test normal, replace the seat back heater element.
  5. Disconnect the X2, X5 harness connectors at the MSM.
  6. Test for 850-300K ohms between the signal circuit terminal 4 X5 and the low reference circuit terminal 2 X2.
    7. ⇒If greater than the specified range, test the signal and low reference circuits for a short to voltage or an open/high resistance. If the circuits test normal, replace the seat back heater element/temperature sensor.
    ⇒If less than the specified range, test for a short between the signal and low reference circuits. If the circuits test normal, replace the seat back heater element/temperature sensor.
  7. Connect the X1, X2, X5 harness connectors at the MSM.
  8. Disconnect the harness connector at the seat back heater element/temperature sensor.
  9. Ignition ON, test for 4.8-5.2 volts between the signal circuit terminal C and ground.
    10. ⇒If greater than the specified range, test the signal circuit for a short to voltage. If the circuit tests normal, replace the MSM.
    ⇒ If less than the specified range, test the signal circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the MSM.
  10. If all circuits test normal, replace the MSM.

B2180 0A, B2180 0B, B2180 0C, B2180 0D, B2180 0E, B2180 04, or B2180 1F

  1. Ignition OFF, disconnect the X3 harness connector at the MSM.
  2. Ignition ON, verify that a test lamp illuminates between the B+ circuit terminal 5 and ground.
    3. ⇒If the test lamp does not illuminate, test the B+ circuit for a short to ground or an open/high resistance.
  3. Ignition OFF, connect the X3 harness connector at the MSM and disconnect the X1 harness connector at the MSM.

    4. Important: When measuring the resistance, the resistance values are based on the seat being at room temperature of 20°C (68°F).

  4. Test for 3.5-11.5 ohms between control circuit terminal 6 and control circuit terminal 4.
    5. ⇒If greater than the specified range, test the control circuits for an open/high resistance. If the circuits test normal, replace the seat back heater element.
    ⇒If less than the specified range, test for a short between the control circuits. If the circuits test normal, replace the seat back heater element.
  5. Disconnect the X2, X5 harness connectors at the MSM.
  6. Test for 850-300K ohms between the signal circuit terminal 3 X5 and the low reference circuit terminal 5 X2.
    7. ⇒If greater than the specified range, test the signal and low reference circuits for a short to voltage or an open/high resistance. If the circuits test normal, replace the seat back heater element/temperature sensor.
    ⇒If less than the specified range, test for a short between the signal and low reference circuits. If the circuits test normal, replace the seat back heater element/temperature sensor.
  7. Connect the X1, X2, X5 harness connectors at the MSM.
  8. Disconnect the harness connector at the seat back heater element/temperature sensor.
  9. Ignition ON, test for 4.8-5.2 volts between the signal circuit terminal C and ground.
    10. ⇒If greater than the specified range, test the signal circuit for a short to voltage. If the circuit tests normal, replace the MSM.
    ⇒ If less than the specified range, test the signal circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the MSM.
  10. If all circuits test normal, replace the MSM.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

    •  Driver or Passenger Seat Back Cushion Heater Replacement
    •  Control Module References for the MSM replacement, setup, and programming

DTC B1935 or B2180 Without Memory, With HP2

Diagnostic Instructions
    • Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.
    • Review Strategy Based Diagnosis for an overview of the diagnostic approach.
    •  Diagnostic Procedure Instructions provides an overview of each diagnostic category.

DTC Descriptors

DTC B1935 04: Left Seat Back Heater Circuit Open

DTC B1935 0A: Left Seat Back Heater Circuit Rate of Change Below Threshold

DTC B1935 0B: Left Seat Back Heater Circuit Current Above Threshold

DTC B1935 0C: Left Seat Back Heater Circuit Current Below Threshold

DTC B1935 0D: Left Seat Back Heater Circuit Resistance Above Threshold

DTC B1935 0E: Left Seat Back Heater Circuit Resistance Below Threshold

DTC B1935 1F: Left Seat Back Heater Circuit Intermittent

DTC B2180 04: Right Seat Back Heater Circuit Open

DTC B2180 0A: Right Seat Back Heater Circuit Rate of Change Below Threshold

DTC B2180 0B: Right Seat Back Heater Circuit Current Above Threshold

DTC B2180 0C: Right Seat Back Heater Circuit Current Below Threshold

DTC B2180 0D: Right Seat Back Heater Circuit Resistance Above Threshold

DTC B2180 0E: Right Seat Back Heater Circuit Resistance Below Threshold

DTC B2180 1F: Right Seat Back Heater Circuit Intermittent

Diagnostic Fault Information

Circuit

Short to Ground

Open/High Resistance

Short to Voltage

Signal Performance

Driver Heated Seat Back Element Supply Voltage

B2508 02

B1935 0C, B1935 0D

B2345 00, B2508 01

B1935 0B, B1935 0E

Driver Heated Seat Back Element Supply Control

B2345 00, B2508 02

B1935 0C, B1935 0D

B2345 00, B2508 01

B1935 0B, B1935 0E

Driver Heated Seat Back Temperature Sensor Signal

B2435 02

B1935 04, B1935 1F, B2435 0D

B1935 04, B1935 1F, B2435 0D

B1935 0A, B2345 13, B2345 42, B2345 4B

Driver Heated Seat Back Temperature Sensor Low Reference

--

B1935 04, B1935 1F, B2435 0D

--

B2345 13, B2345 42, B2345 4B

Driver Heated Seat Cushion Element Supply Voltage

B2508 02

B2425 0C, B2425 0D

B2345 00, B2508 01

B2425 0B, B2425 0E

Driver Heated Seat Cushion Element Control

B2345 00, B2508 02

B2425 0C, B2425 0D

B2345 00, B2508 01

B2425 0B, B2425 0E

Driver Heated Seat Cushion Temperature Sensor Signal

B1925 02, B2425 1F

B1925 05, B2425 04, B2425 1F

B1925 05, B2425 04, B2425 1F

B2345 13, B2345 42, B2345 4B, B2425 0A

Driver Heated Seat Cushion Temperature Sensor Low Reference

--

B1925 05, B2425 04, B2425 1F

--

B2345 13, B2345 42, B2345 4B

Passenger Heated Seat Back Element Supply Voltage

B2508 02

B2180 0C, B2180 0D

B2345 00, B2508 01

B2180 0B, B2180 0E

Passenger Heated Seat Back Element Control

B2345 00, B2508 02

B2180 0C, B2180 0D

B2345 00, B2508 01

B2180 0B, B2180 0E

Passenger Heated Seat Back Temperature Sensor Signal

B2440 02

B2180 04, B2180 1F, B2440 05

B2180 04, B2180 1F, B2440 05

B2180 0A, B2345 13, B2345 42, B2345 4B

Passenger Heated Seat Back Temperature Sensor Low Reference

--

B2180 04, B2180 1F, B2440 05

--

B2345 13, B2345 42, B2345 4B

Passenger Heated Seat Cushion Element Supply Voltage

B2508 02

B2430 0C, B2430 0D

B2345 00, B2508 01

B2430 0B, B2430 0E

Passenger Heated Seat Cushion Element Control

B2345 00, B2508 02

B2430 0C, B2430 0D

B2345 00, B2508 01

B2430 0B, B2430 0E

Passenger Heated Seat Cushion Temperature Sensor Signal

B2170 02, B2430 1F

B2430 04, B2430 1F, B2170 05

B2430 04, B2430 1F, B2170 05

B2345 13, B2345 42, B2345 4B, B2430 0A

Passenger Heated Seat Cushion Temperature Sensor Low Reference

--

B2430 04, B2430 1F, B2170 05

--

B2345 13, B2345 42, B2345 4B

Circuit/System Description

When the heated seat function is active, the heated seat module (HSM) supplies battery voltage through the element supply voltage circuit to the seat heater elements. The module controls the seat temperature by providing a PWM ground through the heated seat element control circuit to the seat heater elements. The module then monitors the current flow through the heating element and the temperature sensor rate of change to verify correct operation.

Conditions for Running the DTC

The HSM must be powered and the heated seat must be enabled.

Conditions for Setting the DTC

B1935 04, B2180 04

The module does not detect a temperature change within 210 seconds.

B1935 0A, B2180 0A

The module detects that the set point temperature has not been reached within 8.5 minutes.

B1935 0B, B1935 0E, B2180 0B, B2180 0E

By measuring output current, the module calculates that the heating element resistance is below the minimum resistance.

B1935 0C, B1935 0D, B2180 0C, B2180 0D

By measuring output current, the module calculates that the heating element resistance is above the maximum resistance.

B1935 1F, B2180 1F

The temperature sensor voltage is erratic or changes suddenly.

Action Taken When the DTC Sets

The heated seat back function for the affected seat will be disabled.

Conditions for Clearing the DTC
    • The current DTC clears when the malfunction is no longer present and the power mode changes to OFF then back to ACC or RUN.
    • The history DTC will clear after 50 consecutive fault-free ignition cycles have occurred.

Reference Information

Schematic Reference

Heated/Cooled Seat Schematics

Connector End View Reference

Component Connector End Views

Description and Operation

Heated Seats Description and Operation

Electrical Information Reference

    •  Circuit Testing
    •  Connector Repairs
    •  Testing for Intermittent Conditions and Poor Connections
    •  Wiring Repairs

Scan Tool Reference

Control Module References for scan tool information

Circuit/System Testing

B1935 0A, B1935 0B, B1935 0C, B1935 0D, B1935 0E, B1935 04, or B1935 1F

  1. Ignition OFF, disconnect the X1 harness connector at the HSM.
  2. Test for 3.5-11.5 ohms between control circuit terminal 6 and control circuit terminal 1.
    3. ⇒If greater than the specified range, test the control circuits for an open/high resistance. If the circuits test normal, replace the seat back heater element.
    ⇒If less than the specified range, test for a short between the control circuits. If the circuits test normal, replace the seat back heater element.
  3. Disconnect the X2, X4 harness connectors at the HSM.
  4. Test for 850-300K ohms between the signal circuit terminal 19 X4 and the low reference circuit terminal 5 X2.
    5. ⇒If greater than the specified range, test the signal and low reference circuits for a short to voltage or an open/high resistance. If the circuits test normal, replace the seat back heater element/temperature sensor.
    ⇒If less than the specified range, test for a short between the signal and low reference circuits. If the circuits test normal, replace the seat back heater element/temperature sensor.
  5. Connect the X1, X2, X4 harness connectors at the HSM.
  6. Disconnect the harness connector at the seat back heater element/temperature sensor.
  7. Ignition ON, test for 4.8-5.2 volts between the signal circuit terminal C and ground.
    8. ⇒If greater than the specified range, test the signal circuit for a short to voltage. If the circuit tests normal, replace the HSM.
    ⇒ If less than the specified range, test the signal circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the HSM.
  8. If all circuits test normal, replace the HSM.

B2180 0A, B2180 0B, B2180 0C, B2180 0D, B2180 0E, B2180 04, or B2180 1F

  1. Ignition OFF, disconnect the X1 harness connector at the HSM.
  2. Test for 3.5-11.5 ohms between control circuit terminal 3 and control circuit terminal 4.
    3. ⇒If greater than the specified range, test the control circuits for an open/high resistance. If the circuits test normal, replace the seat back heater element.
    ⇒If less than the specified range, test for a short between the control circuits. If the circuits test normal, replace the seat back heater element.
  3. Disconnect the X2, X4 harness connectors at the HSM.
  4. Test for 850-300K ohms between the signal circuit terminal 10 X4 and the low reference circuit terminal 7 X2.
    5. ⇒If greater than the specified range, test the signal and low reference circuits for a short to voltage or an open/high resistance. If the circuits test normal, replace the seat back heater element/temperature sensor.
    ⇒If less than the specified range, test for a short between the signal and low reference circuits. If the circuits test normal, replace the seat back heater element/temperature sensor.
  5. Connect the X1, X2, X4 harness connectors at the HSM.
  6. Disconnect the harness connector at the seat back heater element/temperature sensor.
  7. Ignition ON, test for 4.8-5.2 volts between the signal circuit terminal C and ground.
    8. ⇒If greater than the specified range, test the signal circuit for a short to voltage. If the circuit tests normal, replace the HSM.
    ⇒ If less than the specified range, test the signal circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the HSM.
  8. If all circuits test normal, replace the HSM.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

    •  Driver or Passenger Seat Back Cushion Heater Replacement
    •  Control Module References for the HSM replacement, setup, and programming