GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 GMC_Truck 🢒 2004 🢒 GMC Sierra Denali 🢒 DTC 🢒 DTC B1825

Circuit Description

The seat recline motor is equipped with a potentiometer type position sensor used by the driver seat module (DSM) to determine the position of the seat back. The motor position sensor is supplied with 5-volt reference and ground circuits from the DSM. The position sensor signal circuit is referenced from ground within the DSM. The signal voltage monitored by the DSM ranges from 0.39-4.58 volts and is determined by the wiper location on the resistor within the motor position sensor. The position sensor circuit voltage level is used by the DSM to determine the position of the seat back when storing or recalling memory position settings.

Conditions for Running the DTC

The system voltage must be between 9-16 volts.

Conditions for Setting the DTC

The recline motor position sensor signal circuit voltage level to the DSM is not within the 0.39-4.58 volt range.

Action Taken When the DTC Sets

The recline motor will not function during memory or exit position recall operation.

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.

Diagnostic Aids

A short to voltage on a sensor signal circuit or an open ground may effect other sensors using common 5-volt reference and ground circuits causing the following DTCs to set:

    • B2435
    • B2440
    • B3606

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 low voltage range.

    2.

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

    3.

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

Step

Action

Values

Yes

No

Schematic Reference: Driver Seat Schematics

Connector End View Reference: Power Seat Connector End Views

1

Did you perform the Power Seat Systems Diagnostic System Check?

--

Go to Step 2

Go to Diagnostic System Check - Power Seat Systems

2
  1. Install a scan tool.
  2. With a scan tool, observe the Recline Position Sensor parameter in the driver seat module (DSM) Sensor Data list.

Is the Recline Position Sensor parameter within the specified range?

0.39-4.58 V

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

Go to Step 3

3

  1. Disconnect the recline motor position sensor.
  2. With a scan tool, observe the Recline Position Sensor parameter.

Is the Recline Position Sensor parameter less than the specified value?

0.39 V

Go to Step 4

Go to Step 8

4

  1. Connect a 3-ampere fused jumper wire between the signal circuit of the recline position sensor and the 5-volt reference circuit of the recline position sensor.
  2. With a scan tool, observe the Recline Position Sensor parameter.

Is the Recline Position Sensor parameter greater than the specified value?

4.58 V

Go to Step 5

Go to Step 7

5

  1. Disconnect the fused jumper wire.
  2. Measure the voltage between the 5-volt reference and the signal circuit of the recline position sensor.

Is the voltage greater than the specified value?

5 V

Go to Step 6

Go to Step 10

6

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

Did you find and correct the condition?

--

Go to Step 15

Go to Step 12

7

Test the 5-volt reference circuit of the recline position sensor for one of the following conditions:

    • A short to ground
    • A high resistance
    • An open

Refer to Circuit Testing and to Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 15

Go to Step 9

8

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

Did you find and correct the condition?

--

Go to Step 15

Go to Step 12

9

Test the signal circuit of the recline position sensor for one of the following conditions:

    • A short to ground
    • A high resistance
    • An open

Refer to Circuit Testing and to Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 15

Go to Step 12

10

Test the low reference circuit of the recline position sensor for one of the following conditions:

    • A high resistance
    • An open

Refer to Circuit Testing and to Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 15

Go to Step 11

11

Inspect for poor connections at the harness connector of the recline position sensor . Refer to Testing for Intermittent Conditions and Poor Connections and to Connector Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 15

Go to Step 13

12

Inspect for poor connections at the harness connector of the DSM. Refer to Testing for Intermittent Conditions and Poor Connections and to Connector Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 15

Go to Step 14

13

Replace the recline position sensor.

Did you complete the replacement?

--

Go to Step 15

--

14

Replace the DSM. Refer to Memory Seat Control Module Replacement .

Did you complete the replacement?

--

Go to Step 15

--

15
  1. Use the scan tool in order to clear the DTCs.
  2. Operate the vehicle within the Conditions for Running the DTC.

Does the DTC reset?

--

Go to Step 2

System OK