U1651
DTC U1651
Diagnostic Instructions
* Perform the Diagnostic System Check - Vehicle (Initial Inspection and Diagnostic Overview) prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis (Initial Inspection and Diagnostic Overview) for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions (Initial Inspection and Diagnostic Overview) provides an overview of each diagnostic category.
DTC Descriptor
DTC U1651 00
- Steering Wheel Sensor Malfunction
Diagnostic Fault Information
Circuit Description
The steering wheel angle sensor communicates to the electronic brake control module (EBCM) through a dedicated CAN Bus serial data circuit. Any fault on either or both CAN Bus circuit will cause DTC U1651 to be set in the EBCM module.
Conditions for Running the DTC
The system voltage is between 9-16 volts.
Conditions for Setting the DTC
A supervised periodic message that includes the transmitter module availability has not been received on one or both CAN Bus serial data circuits.
Action Taken When the DTC Sets
The vehicle stability system will not function.
Conditions for Clearing the DTC
* A current DTC clears when the malfunction is no longer present.
* A history DTC clears when the module ignition cycle counter reaches the reset threshold of 50, without a repeat of the malfunction.
Diagnostic Aids
* Sometimes, while diagnosing a specific customer concern or after a repair, you may notice a history U-code present. However, there is no associated "current" or "active" status. Loss-of- communication U-codes such as these can set for a variety of reasons. Many times, they are transparent to the vehicle operator and technician, and/or have no associated symptoms. Eventually, they will erase themselves automatically after a number of fault-free ignition cycles. This condition would most likely be attributed to one of these scenarios:
- A control module on the data communication circuit was disconnected while the communication circuit is awake.
- Power to one or more modules was interrupted during diagnosis.
- A low battery condition was present, so some control modules stop communicating when battery voltage drops below a certain threshold.
- Battery power was restored to the vehicle and control modules on the communication circuit did not all re-initialize at the same time.
- If a loss-of-communication U-code appears in history for no apparent reason, it is most likely associated with one of the scenarios above. These are all temporary conditions and should never be interpreted as an intermittent fault, causing you to replace a part.
* A control module may have a U-code stored in history that does not require any repairs. Issues with late or corrupted messages between control modules can be temporary with no apparent symptom or complaint; this does not mean the control module is faulty. Do not replace a control module based only on a history U-code.
* Do not replace a control module reporting a U-code. The U-code identifies which control module needs to be diagnosed for a communication issue.
* This diagnostic can be used for any control module that is not communicating, regardless of the type of serial data circuit it is connected to, providing the vehicle is equipped with the control module.
Reference Information
Schematic Reference
* Data Communication Schematics (Electrical Diagrams)
* Antilock Brake System Schematics ([1][2]Antilock Brakes / Traction Control Systems)
Connector End View Reference
Component Connector End Views (Connector Views)
Electrical Information Reference
* Circuit Testing (Component Tests and General Diagnostics)
* Connector Repairs (Component Tests and General Diagnostics)
* Testing for Intermittent Conditions and Poor Connections (Component Tests and General Diagnostics)
* Wiring Repairs (Component Tests and General Diagnostics)
Scan Tool Reference
Control Module References (Programming and Relearning) for scan tool information
Circuit/System Verification
With a scan tool, verify that all of the vehicle stability enhancement system (VSES) data is present in the EBCM module data list.
Circuit/System Testing
1. Ignition OFF, disconnect the harness connector of the appropriate sensor.
2. Test for less than 10 ohm between sensor connector terminal and ground.
• If greater than the specified range, test the ground circuit for an open/high resistance.
3. Ignition ON, verify that a test lamp illuminates between the sensor B+ connector terminal and ground.
• If the test lamp does not illuminate, test the B+ circuit for a short to ground or an open/high resistance. If the circuit fuse is open and the circuit tests normal, replace the sensor.
4. Ignition OFF, disconnect the harness connector at the EBCM.
5. Ignition ON, test for less than 3 V at the appropriate CAN bus terminals:
• If greater than the specified range, test the circuits for a short to voltage.
6. Test for greater than 5 ohm between the appropriate CAN bus connector terminals and ground:
• If less than the specified range, test the circuits for a short to ground.
7. Test for greater than 5 ohm between appropriate CAN bus terminals.
• If less than the specified range, test for a short between the CAN bus serial data circuits.
8. Test for less than 5 ohm between sensor terminal and EBCM terminal for each individual CAN bus circuit:
• If greater than the specified range, test the appropriate serial data circuit for an open/high resistance.
9. If all circuits test normal, replace the sensor.
Repair Instructions
Perform the Diagnostic Repair Verification (Verification Tests) after completing the diagnostic procedure.
* Steering Angle Sensor Centering (Procedures)
* Steering Wheel Position Sensor or Steering Shaft Lower Bearing Replacement (Steering Wheel Position Sensor or Steering Shaft Lower Bearing Replacement)
* Control Module References (Programming and Relearning) for sensor replacement, setup, and programming