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For 1990-2009 cars only

DTC B1860 w/o Massaging Lumbar-AM3

Circuit Description

The position sensor that sets this diagnostic trouble code (DTC) is attached to the lumbar motor it monitors. It receives a 5-volt reference and low reference from the memory seat module (MSM). The sensor sends a voltage signal that varies with the movement of the seat through the signal circuit to the MSM. Then based on this voltage signal, the MSM determines the position of the seat.

DTC Descriptor

This diagnostic procedure supports the following DTC:

DTC B1860 Seat Lumbar Vertical Position Sensor Circuit

Conditions for Running the DTC

The MSM must be powered and can not have B1327 - Battery Voltage Low set as an active DTC for this DTC to set.

Conditions for Setting the DTC

If the MSM sees the analog input from this sensor as either lower than 0.25 volt or higher than 4.75 volt , the sensor will be considered out of range and the MSM will set this DTC.

Action Taken When the DTC Sets

The MSM disables the memory recall and easy exit/entry action commands of the motor monitored by the sensor. The motor will respond to manual positioning commands.

Conditions for Clearing the DTC

The MSM will clear the DTC as an active malfunction when it sees the analog input from this sensor as between 0.25 volt and 4.75 volt during one cycle of checking the MSM inputs.

Diagnostic Aids

    • All position sensors use common ground and 5-volt reference circuits.
    • If the 5-volt reference circuit is shorted to voltage multiple codes will set.
    • If the 5-volt reference circuit is shorted to ground multiple codes will set.
    • If the sensor ground circuit is open multiple codes will set.

Test Description

The numbers below refer to the step numbers on the diagnostic table.

  1. Tests for the proper operation of the circuit in the low voltage range.

  2. Tests for the proper operation of the signal circuit in the high voltage range. If the fuse in the jumper opens when you perform this test, the signal circuit is shorted to ground.

  3. Tests for a short to voltage in the 5-volt reference circuit.

  4. This step verifies the repair.

Step

Action

Value(s)

Yes

No

Schematic Reference: Driver 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

  1. Install a scan tool.
  2. Turn ON the ignition, with the engine OFF.
  3. With a scan tool, observe the Lumbar Vertical Sensor parameter in the Memory Seat Module (MSM) Sensor data list.

Does the scan tool indicate that the Lumbar Vertical Sensor parameter is within the specified range?

0.25-4.75 V

Go to Testing for Intermittent Conditions and Poor Connections in Wiring Systems

Go to Step 3

3

  1. Turn OFF the ignition.
  2. Disconnect the lumbar vertical position sensor.
  3. Turn ON the ignition, with the engine OFF.
  4. With a scan tool, observe the Lumbar Vertical Sensor parameter.

Does the scan tool indicate that the Lumbar Vertical Sensor parameter is less than the specified value?

2.00 V

Go to Step 4

Go to Step 10

4

  1. Turn OFF the ignition.
  2. Connect a 3-amp fused jumper wire between the 5-volt reference circuit of the sensor connector and the signal circuit of the sensor connector.
  3. Turn ON the ignition, with the engine OFF.
  4. With a scan tool, observe the Lumbar Vertical Sensor parameter.

Does the scan tool indicate that the Lumbar Vertical Sensor parameter is greater than the specified value?

4.75 V

Go to Step 5

Go to Step 8

5

  1. Disconnect the fused jumper wire.
  2. Measure the voltage between the 5-volt reference circuit of the sensor connector and the low reference circuit of the sensor connector.

Does the voltage measure less than the specified value?

5.50 V

Go to Step 6

Go to Step 7

6

  1. Turn OFF the ignition.
  2. Disconnect the negative battery cable.
  3. Measure the resistance from the low reference circuit of the lumbar vertical position sensor to a good ground.

Does the resistance measure less than the specified value?

5 ohms

Go to Step 12

Go to Step 11

7

Test the 5-volt reference circuit of the lumbar vertical position sensor for a short to voltage. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 16

Go to Step 13

8

Test the 5-volt reference circuit of the lumbar vertical position sensor for a short to ground, a high resistance, or an open. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 16

Go to Step 9

9

Test the signal circuit of the lumbar vertical position sensor for a short to ground, a high resistance, or an open. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 16

Go to Step 13

10

Test the signal circuit of the lumbar vertical position sensor for a short to voltage. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 16

Go to Step 13

11

  1. Disconnect the MSM harness connector C2.
  2. Test the low reference circuit of the lumbar vertical position sensor for a high resistance or an open. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 16

Go to Step 13

12

Inspect for poor connections at the harness connector of the lumbar vertical 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 16

Go to Step 14

13

Inspect for poor connections at the harness connector of the MSM. 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 16

Go to Step 15

14

Replace the seat lumbar vertical sensor. Refer to Front Seat Lumbar Support Replacement .

Did you complete the replacement?

--

Go to Step 16

--

15

Replace the MSM. Refer to Control Module References in Computer/Integrating Systems for replacement, setup, and programming.

Did you complete the replacement?

--

Go to Step 16

--

16

  1. Use the scan tool in order to clear the DTCs.
  2. Operate the vehicle within the Conditions for Running the DTC as specified in the supporting text.

Does the DTC reset?

--

Go to Step 2

System OK

DTC B1860 with Massaging Lumbar-AM3

Circuit Description

The position sensor that sets this diagnostic trouble code (DTC) is attached to the lumbar directional motor it monitors. It receives a 5-volt reference and low reference from the memory seat module (MSM). The sensor sends a voltage signal that varies with the movement of the seat through the signal circuit to the MSM. Then based on this voltage signal, the MSM determines the position of the seat.

DTC Descriptor

This diagnostic procedure supports the following DTC:

DTC B1860 Seat Lumbar Vertical Position Sensor Circuit

Conditions for Running the DTC

The MSM must be powered and can not have B1327 - Battery Voltage Low set as an active DTC for this DTC to set.

Conditions for Setting the DTC

If the MSM sees the analog input from this sensor as either lower than 0.25 volt or higher than 4.75 volt, the sensor will be considered out of range and the MSM will set this DTC.

Action Taken When the DTC Sets

The MSM disables the memory recall and easy exit/entry action commands of the motor monitored by the sensor. The motor will respond to manual positioning commands.

Conditions for Clearing the DTC

The MSM will clear the DTC as an active malfunction when it sees the analog input from this sensor as between 0.25 volt and 4.75 volt during one cycle of checking the MSM inputs.

Diagnostic Aids

    • All position sensors use common ground and 5-volt reference circuits.
    • If the 5-volt reference circuit is shorted to voltage multiple codes will set.
    • If the 5-volt reference circuit is shorted to ground multiple codes will set.
    • If the 5-volt reference circuit is open at the massage module multiple codes will set.
    • If the sensor ground circuit is open multiple codes will set.

Test Description

The numbers below refer to the step numbers on the diagnostic table.

  1. Tests for the proper operation of the signal circuit in the high voltage range.

  2. Tests for the proper operation of the signal circuit in the low voltage range.

  3. This step tests the integrity of the lumbar vertical position sensor signal circuit. If the fuse in the jumper wire opens when you perform this test, a short to battery voltage may have occurred.

  4. This step verifies the repair.

Step

Action

Value(s)

Yes

No

Schematic Reference: Driver 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

  1. Install a scan tool.
  2. Turn ON the ignition, with the engine OFF.
  3. With a scan tool, observe the Lumbar Vertical Sensor parameter in the Memory Seat Module (MSM) Sensor data list.

Does the scan tool indicate that the Lumbar Vertical Sensor parameter is within the specified range?

0.25-4.75 V

Go to Testing for Intermittent Conditions and Poor Connections in Wiring Systems

Go to Step 3

3

  1. Turn OFF the ignition.
  2. Disconnect the lumbar vertical position sensor.
  3. Turn ON the ignition, with the engine OFF.
  4. Measure the voltage from the 5-volt reference circuit of the lumbar vertical sensor to a good ground.

Does the voltage measure within the specified range?

4.50-5.50 V

Go to Step 4

Go to Step 18

4

Measure the voltage from the 5-volt reference circuit of the lumbar vertical sensor to the low reference circuit of the lumbar vertical sensor.

Does the voltage measure within the specified range?

4.50-5.50 V

Go to Step 5

Go to Step 19

5

  1. Turn OFF the ignition.
  2. Disconnect the massage module.
  3. Turn ON the ignition, with the engine OFF.
  4. Measure the voltage from the 5-volt reference circuit of the massage module to a good ground.

Does the voltage measure within the specified range?

4.50-5.50 V

Go to Step 6

Go to Step 20

6

Measure the voltage from the battery positive voltage circuit of the massage module to a good ground.

Does the voltage measure within the specified range?

9-15 V

Go to Step 7

Go to Step 21

7

  1. Turn OFF the ignition.
  2. Connect the massage module connector.
  3. Turn ON the ignition, with the engine OFF.
  4. With a scan tool, observe the Lumbar Vertical Sensor parameter.

Does the scan tool indicate that the Lumbar Vertical Sensor parameter is greater than the specified value?

4.75 V

Go to Step 8

Go to Step 10

8

  1. Connect a 3-amp fused jumper wire from the signal circuit of the lumbar vertical position sensor to a good ground.
  2. With a scan tool, observe the Lumbar Vertical Sensor parameter.

Does the scan tool indicate that the Lumbar Vertical Sensor parameter is less than the specified value?

0.25 V

Go to Step 15

Go to Step 9

9

  1. Turn OFF the ignition.
  2. Disconnect the massage module harness connector.
  3. Turn ON the ignition, with the engine OFF.
  4. With a scan tool observe the Lumbar Vertical Sensor parameter.

Does the scan tool indicate that the Lumbar Vertical Sensor parameter is less than the specified value?

0.25 V

Go to Step 11

Go to Step 13

10

  1. Turn OFF the ignition.
  2. Disconnect the massage module connector.
  3. Connect a 3-amp fused jumper wire between the 5-volt reference circuit of the module connector and the lumbar vertical position sensor signal circuit of the module connector Pin-M.
  4. Turn ON the ignition, with the engine OFF.
  5. With a scan tool, observe the Lumbar Vertical Sensor parameter.

Does the scan tool indicate that the Lumbar Vertical Sensor parameter is greater than the specified value?

4.50 V

Go to Step 14

Go to Step 12

11

Test the lumbar position sensor signal circuit between the sensor and the massage module for a high resistance or an open. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 25

Go to Step 16

12

Test the lumbar vertical position sensor signal circuit between the MSM and the massage module for a short to ground, a high resistance, or an open. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 25

Go to Step 17

13

Test the lumbar vertical position sensor signal circuit between the MSM and the massage module for a short to voltage. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 25

Go to Step 17

14

Test the lumbar position sensor signal circuit between the sensor and the massage module 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 25

Go to Step 16

15

Inspect for poor connections at the harness connector of the lumbar vertical position 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 25

Go to Step 22

16

Inspect for poor connections at the harness connector of the massage 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 25

Go to Step 23

17

Inspect for poor connections at the harness connector of the MSM. 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 25

Go to Step 24

18

Repair the open in the 5-volt reference circuit of the lumbar vertical position sensor. Refer to Wiring Repairs in Wiring Systems.

Did you complete the repair?

--

Go to Step 25

--

19

Repair the open in the low reference circuit of the lumbar vertical position sensor. Refer to Wiring Repairs in Wiring Systems.

Did you complete the repair?

--

Go to Step 25

--

20

Repair the open in the 5-volt reference circuit of the massage module. Refer to Wiring Repairs in Wiring Systems.

Did you complete the repair?

--

Go to Step 25

--

21

Repair the open in the battery positive voltage circuit of the massage module. Refer to Wiring Repairs in Wiring Systems.

Did you complete the repair?

--

Go to Step 25

--

22

Replace the seat lumbar vertical position sensor. Refer to Front Seat Lumbar Support Replacement .

Did you complete the replacement?

--

Go to Step 25

--

23

Replace the massage module. Refer to Control Module References in Computer/Integrating Systems for replacement, setup, and programming.

Did you complete the replacement?

--

Go to Step 25

--

24

Replace the MSM. Refer to Control Module References in Computer/Integrating Systems for replacement, setup, and programming.

Did you complete the replacement?

--

Go to Step 25

--

25

  1. Use the scan tool in order to clear the DTCs.
  2. Operate the vehicle within the Conditions for Running the DTC as specified in the supporting text.

Does the DTC reset?

--

Go to Step 2

System OK