U0428-00

U0428-00-IMPLAUSIBLE DATA RECEIVED FROM STEERING ANGLE SENSOR MODULE

For a complete wiring diagram, refer to the Wiring Information.

Theory of Operation

The Electro-Hydraulic Power Steering (EHPS) Assembly contains a control module, brushless electric motor, and hydraulic pump integrated into a single unit. The EHPS Assembly draws power from the 12-Volt electrical system and provides the necessary flow and pressure to the steering gear to provide normal power steering independent of the gasoline engine. The EHPS Assembly requires communication over the CAN C bus to function properly. The output flow of the EHPS Assembly is varied as a function of Steering Wheel Rate (received from SAS Module) and Vehicle Speed (received from ABS Module) in order to provide the optimum flow of power steering fluid to the steering gear under all operating conditions. The pump will start to provide steering assist when a hybrid active (vehicle started) or a Vehicle speed message greater than 5 kph (3 mph) is received on CAN C. If both the Vehicle Speed and Hybrid Active messages are missing at vehicle startup, the EHPS Assembly will not operate. If the Vehicle Speed message is lost during operation the EHPS Module will use a default vehicle speed of 85 km/h (59 mph) to calculate desired flow and as a result, steering effort will no longer be speed sensitive. If the Steering Wheel Position message is lost the EHPS Module will use a default steering wheel rate of 230°/sec to calculate desired flow and as a result, steering effort may be higher on evasive steering maneuvers. The EHPS Assembly will resume normal operation automatically once any missing message or out of range condition noted above is restored to normal.

- When Monitored:
Continuously while the system is active.

- Set Condition:
An error message has been received over the bus from the Steering Angle Sensor (SAS).





1. ACTIVE DTC

NOTE: Diagnose all communication DTCs before continuing.

1. Ignition on, engine not running.
2. With a scan tool, view DTCs.

Is the status Active for this DTC?

Yes

- Go To 2

No

- Test complete. The condition or conditions that originally set this DTC are not present at this time. Using the wiring diagrams as a guide, check all related splices and connectors for signs of water intrusion, corrosion, pushed out or bent terminals, and correct pin tension.

2. SAS COMMUNICATION RELATED DTCs IN OTHER MODULES
1. With a scan tool check for SAS communication related DTCs in other modules on the CAN Bus.

Are there any SAS communication related DTCs in other modules on the CAN Bus at this time?

Yes

- Replace the SAS. Steering Column Module - Removal.
- Perform the EHPS VERIFICATION TEST. EHPS Verification Test.

No

- Replace the Electro-Hydraulic Power Steering (EHPS) Assembly. Power Steering Pump - Removal.
- Perform the EHPS VERIFICATION TEST. EHPS Verification Test.