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Makes 🢒 Cadillac 🢒 2000 🢒 Eldorado 🢒 Brakes 🢒 Antilock Brake System 🢒 DTC C1287 Steering Sensor Rate Malfunction

DTC C1287 Steering Sensor Rate Malfunction w/JL4


Object Number: 592760 Size: MF
ABS Components
Vehicle Stability Enhancement System (w/JL4)
Handling ESD Sensitive Parts Notice

Circuit Description

The steering wheel position sensor supplies 1 analog input and 2 digital inputs, Phase A and Phase B, to the EBCM. By interpreting the relationship between the inputs, the EBCM can determine the position of the steering wheel and the direction of steering wheel rotation.

Steer angle centering is the process by which the EBCM calibrates the steering sensor output so that the output reads zero when the steering wheel is centered. Using the yaw rate input, lateral accelerometer input, and wheel speed sensor inputs, the initial steering center position is calculated after driving greater than 10 km/h (6 mph) for more than 10 seconds in a straight line on a level surface.

Conditions for Running the DTC

The EBCM performs 3 different tests to detect a DTC condition. The numbers below correspond to the numbers in Conditions for Setting the DTC.

  1. The steer sensor rate test runs with the ignition ON.
  2. The steer sensor analog mismatch test runs under the following conditions:
    3. • The digital steer rate is less than 10 degrees/second.
    • The absolute value of the analog steer angle is less than 135 degrees.
  3. The analog cross-comparison test runs under the following conditions:
    4. • The VSES is active.
    • The digital steer rate is less than 10 degrees/second.

Conditions for Setting the DTC

One of the following conditions occur:

  1. The steer rate (speed that the steering wheel appears to be turning) is greater than 1000 degrees/second.
  2. The difference between the analog steer angle and digital steer angle is greater than 20 degrees continuously for 5 seconds.
  3. The difference between the analog steer angle and digital steer angle is greater than 20 degrees for 1 second. Under this condition, this DTC will set along with DTC C1281.

Action Taken When the DTC Sets
    • The EBCM disables the VSES for the duration of the ignition cycle.
    • The DIC displays the SERVICE STABILITY SYS message.
    • The ABS/TCS remains functional.

Conditions for Clearing the DTC
    • The condition for the DTC is no longer present (the DTC is not current) and you used the scan tool Clear DTC function.
    • The condition for the DTC is no longer present (the DTC is not current) and you used the On-Board Diagnostics Clear DTC function.
    • The EBCM automatically clears the history DTC when a current DTC is not detected in 50 consecutive drive cycles.

Diagnostic Aids
    • During diagnosis, park the vehicle on a level surface.
    • Check the vehicle for proper alignment. The car should not pull in either direction while driving straight on a level surface.
    • Find out from the driver under what conditions the DTC was set (when the DIC displayed the SERVICE STABILITY SYS message). This information will help to duplicate the failure.
    • The Snapshot function on the scan tool can help find an intermittent DTC.

Test Description

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

  1. Perform the Steering Position Sensor Test in order to verify that the steering wheel position sensor (SWPS) is operating properly.

    2.

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

    3.

  3. 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.

    4.

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

    5.

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

Step

Action

Values

Yes

No

Schematic Reference: Antilock Brake System Schematics

1

Did you perform the ABS Diagnostic System Check?

--

Go to Step 2

Go to Diagnostic System Check - ABS

2

  1. Install a scan tool.
  2. Turn ON the ignition, with the engine OFF.
  3. Use the scan tool in order to perform the Steering Position Sensor Test in the Delco/Bosch ABS/TCS ICCS2 Special Functions.

Did the steering wheel position sensor (SWPS) pass the test?

--

Go to Diagnostic Aids

Go to Step 3

3
  1. Install a scan tool.
  2. Turn ON the ignition, with the engine OFF.
  3. With the scan tool, observe the Analog Steering Wheel Position Input parameter in the Delco/Bosch ABS/TCS ICCS2 data list.

Does the scan tool indicate that the Analog Steering Wheel Position Input parameter is within the specified range?

0.1-4.9 V

Go to Step 13

Go to Step 4

4

  1. Turn OFF the ignition.
  2. Disconnect the steering wheel position sensor (SWPS).
  3. Turn ON the ignition, with the engine OFF.
  4. With the scan tool, observe the Analog Steering Wheel Position Input parameter.

Does the scan tool indicate that the Analog Steering Wheel Position Input parameter is less than the specified value?

0.1 V

Go to Step 5

Go to Step 11

5

  1. Turn OFF the ignition.
  2. Connect a 3 amp fused jumper wire between the 5 volt reference circuit of the steering wheel position sensor (SWPS) and the signal circuit of the steering wheel position sensor (SWPS).
  3. Turn ON the ignition, with the engine OFF.
  4. With the scan tool, observe the Analog Steering Wheel Position Input parameter.

Does the scan tool indicate that the Analog Steering Wheel Position Input parameter is greater than the specified value?

4.9 V

Go to Step 6

Go to Step 9

6

  1. Disconnect the fused jumper wire.
  2. Measure the voltage between the 5 volt reference circuit of the steering wheel position sensor (SWPS) and the ground circuit of the steering wheel position sensor (SWPS).

Does the voltage measure less than the specified value?

5 V

Go to Step 7

Go to Step 8

7

  1. Turn OFF the ignition.
  2. Disconnect the negative battery cable. Refer to Battery Negative Cable Disconnection and Connection in Engine Electrical.
  3. Measure the resistance from the ground circuit of the steering wheel position sensor (SWPS) to a good ground.

Does the resistance measure less than the specified value?

5 ohms

Go to Step 15

Go to Step 12

8

Test the 5 volt reference circuit of the steering wheel position sensor (SWPS) 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 19

Go to Step 16

9

Test the 5 volt reference circuit of the steering wheel position sensor (SWPS) for the following conditions:

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

Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 19

Go to Step 10

10

Test the analog signal circuit of the steering wheel position sensor (SWPS) for the following conditions:

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

Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 19

Go to Step 16

11

Test the analog signal circuit of the steering wheel position sensor (SWPS) 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 19

Go to Step 16

12
  1. Disconnect the EBCM.
  2. Test the ground circuit of the steering wheel position sensor (SWPS) 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 19

Go to Step 16

13

Test the digital phase A signal circuit of the steering wheel position sensor (SWPS) for the following conditions:

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

Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 19

Go to Step 14

14

Test the digital phase B signal circuit of the steering wheel position sensor (SWPS) for the following conditions:

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

Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 19

Go to Step 15

15

Inspect for poor connections at the harness connector of the steering wheel position sensor (SWPS). 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 19

Go to Step 17

16

Inspect for poor connections at the harness connector of the EBCM. 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 19

Go to Step 18

17

Replace the steering wheel position sensor (SWPS). Refer to Steering Shaft, Lower Bearing, and Jacket - Disassemble - Off Vehicle and Steering Shaft, Lower Bearing, and Jacket - Assemble - Off Vehicle in Steering Wheel and Column.

Did you complete the replacement?

--

Go to Step 19

--

18

Replace the EBCM. Refer to Electronic Brake Control Module Replacement .

Did you complete the replacement?

--

Go to Step 19

--

19
  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