Principle of Operation
There are two modes of operation for the EHPS: no steering assistance and steering assistance.
With the engine running and no steering assistance required the pump operates at approximately 80% capacity at a speed of 3,500 rpm. Movement of the steering changes the hydraulic pressure within the circuit which in turn affects the operation of the pump, this is identified at the control electronics by the increase in current, the pump speed is increased to 4,500 rpm and now operates at full (100%) capacity.
The unit's DC motor, is capable of drawing a maximum current of 120 Amperes, but running at an average 11.5 Amperes, powers the system. In standby mode with the engine running but the vehicle stationary the draw is 7.0 Amperes ±10%.
| Condition | Current (Amps) |
|---|---|
| Standby Mode | 7.0 |
| Average Consumption | 11.5 |
| Maximum Assist | 120 |
PRINCIPLE OF OPERATION
The EHPS consists of two connections
- 2-pin cable connection KL30 KL31
- 3-pin connector KL15 KL61 (used to determine if the engine is running) Diagnosis bus (used for communication with the control electronics integrated in the pump)
The pump motor is activated only if the engine is running. If the pump overheats the pump will reduce output to 80%. If the temperature keeps rising, the pump will eventually shut down to protect itself (electronics) from damage.