GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Buick 🢒 2005 🢒 Allure 🢒 Brakes 🢒 Antilock Brake System 🢒 DTC U1650

Circuit Description

The controller area network (CAN) serial data circuit is a high speed serial data bus used to communicate information between the steering angle sensor and the electronic brake control module (EBCM). When the ignition switch is turned to the ON position, the module and the steering angle sensor begin to transmit data between each other.

The CAN bus circuit is monitored continuously after the ignition switch is turned to the ON position.

DTC Descriptor

This diagnostic procedure supports the following DTC:

DTC U1650 Steering Wheel Sensor CAN Malfunction

Conditions for Running the DTC
    • The ignition is ON.
    • The vehicle speed is greater than 40 km/h (25 mph).

Conditions for Setting the DTC

Line interruptions are detected by the CAN message monitor.

Action Taken When the DTC Sets

If equipped, the following actions occur:

    • The EBCM disables the traction control system (TCS)/vehicle stability enhancement system (VSES) and for the duration of the ignition cycle.
    • A malfunction DTC will set.
    • The Stability indicator turns ON.

Conditions for Clearing the DTC
    • The condition for the DTC is no longer present.
    • Using a scan tool clear, DTC function.
    • The EBCM automatically clears the history DTC when a current DTC is not detected in 100 consecutive drive cycles.

Diagnostic Aids

Possible causes of this DTC are as follows:

    • CAN HI and CAN LO circuits shorted together
    • CAN HI or CAN LO circuit shorted to ground
    • CAN HI or CAN LO circuit shorted to voltage

Test Description

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

  1. Tests for a short to ground between the CAN HI and CAN LO circuits.

    2.

  2. Tests the CAN HI and CAN LO circuits for a short together.

    3.

  3. This test checks to see if steering angle sensor is centered.

Step

Action

Yes

No

Schematic Reference: Antilock Brake System Schematics

Connector End View Reference: Antilock Brake System 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. Turn OFF the ignition.
  2. Disconnect the electronic brake control module (EBCM).
  3. Install the J 39700 Universal Pinout Box with the J 39700-530 Cable Adapter to the EBCM harness connector only.
  4. Disconnect the steering angle sensor.
  5. Using the DMM, test the CAN HI and CAN LO circuits for a short to ground between the steering angle sensor and the EBCM. Refer to Testing for Short to Ground in Wiring Systems.

Did you find and correct the condition?

Go to Step 8

Go to Step 3

3

Using the DMM, test the CAN HI and CAN LO circuits between the steering angle sensor and the EBCM for being shorted together. Refer to Circuit Testing in Wiring Systems.

Did you find and correct the condition?

Go to Step 8

Go to Step 4

4

Perform the steering angle sensor centering procedure. Refer to Steering Angle Sensor Centering .

Did you successfully complete the centering procedure?

Go to Step 5

Go to Step 6

5
  1. Use the scan tool in order to clear the DTCs.
  2. Test drive the vehicle. Refer to Diagnostic Test Drive .

Did DTC C1650 reset?

Go to Step 7

Go to Step 8

6

Replace the steering angle sensor. Refer to Steering Wheel Position Sensor or Steering Shaft Lower Bearing Replacement in Steering Wheel and Column.

Did you complete the replacement?

Go to Step 8

--

7

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

Did you complete the replacement?

Go to Step 8

--

8
  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 test.

Does the DTC reset?

Go to Step 2

System OK