GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Cadillac 🢒 2005 🢒 DeVille 🢒 Accessories 🢒 Navigation Systems 🢒 DTC B1825, B1850, B2355, B2365, or B2375

Circuit Description

The position sensor that sets this diagnostic trouble code (DTC) is either attached to the seat directional motor drive cable or directly to the motor it monitors. It receives a 5-volt reference and ground 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 Descriptors

This diagnostic procedure supports the following DTCs:

    • DTC B1825 Seat Recline Position Sensor Circuit
    • DTC B1850 Seat Lumbar Horizontal Position Sensor Circuit
    • DTC B2355 Seat Front Vertical Position Sensor Circuit
    • DTC B2365 Seat Rear Vertical Position Sensor Circuit
    • DTC B2375 Seat Assembly Horizontal 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 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.

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

  4. Tests for a high resistance or an open in the ground circuit.

    5.

  5. 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?

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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 appropriate Sensor parameter in the Memory Seat Module (MSM) Sensor data list.

Does the scan tool indicate that the 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 appropriate sensor connector.
  3. Turn ON the ignition, with the engine OFF.
  4. With a scan tool, observe the Sensor parameter.

Does the scan tool indicate that the 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 appropriate Sensor parameter.

Does the scan tool indicate that the 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 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 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 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 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 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 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 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 appropriate seat position sensor. Refer to Power Seat Drive Cable Replacement , Front Seat Recliner Position Sensor Replacement , or 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