Toyota Camry Hybrid AHV40 Manual page 186

5. EPS ECU
1) General
D The EPS ECU receives signals from
various sensors, judges the current vehicle
condition, and determines the assist current
to be applied to the motor accordingly.
D The diagram on the right describes the
relationship between the steering torque
and the assist power current output.
D The EPS ECU of '07 Camry Hybrid model has a following function:
Item
Basic Control
Inertia Compensation Inertia Compensation
Control
Recovery Control
Damper Control
Voltage Boost Control
System Overheat System Overheat
Protection Control
D The EPS ECU effects cooperative control with the skid control ECU, in order to control the steering
assist torque in accordance with information received from the skid control ECU. This facilitates the
steering operation of the driver, thus realizing a high level of vehicle stability.
D For an outline of Power Steering Cooperative Control Function, see page CH-30.
2) Diagnosis
D If the EPS ECU detects a problem in the EPS system, the P/S warning light that corresponds to the
function in which the malfunction has been detected light up to alert the driver of the malfunction.
D At the same time, the DTC (Diagnosis Trouble Code) are stored in memory. The DTC can be accessed
by using the hand-held tester with CAN VIM (dedicated adapter).
D For details of the DTC that are stored in EPS ECU memory, see the 2007 Camry Hybrid Vehicle Repair
Manual (Pub. No. RM02H0U).
3) Fail-Safe
D If the EPS ECU detects a malfunction in the EPS system, it turns on the P/S warning light in the
combination meter to inform the driver and stops the assist control. As a result, the EPS system
operates in the same manner as manual steering.
D In case of a malfunction, the fail-safe function activates and the ECU effects various controls. For
details, see the 2007 Camry Hybrid Vehicle Repair Manual (Pub. No. RM02H0U).
CHASSIS - STEERING
Assist
Power
Current
Output
Calculates the assist current from the steering torque value and the vehicle
speed, and actuates the motor.
Improves the starting movement of the motor when the driver starts to turn Improves the starting movement of the motor when the driver starts to turn
the steering wheel.
During the short interval between the time the driver fully turns the
steering wheel and the wheels try to recover, this control assists the
recovery force.
Regulates the amount of assist when the driver turns the steering wheel
while driving at high speeds, thus damping the changes in the yaw rate of
the vehicle body.
Boosts the battery voltage in the EPS ECU. It maintains 0 volts when the
driver does not turn the steering wheel or the vehicle is being driven
straight. It effects variable control between 27 to 34 volts in accordance
with the load, when the driver is turning the steering wheel.
Estimates the motor temperature based on the amperage and the current
duration If the temperature exceeds the standard it limits the amperage duration. If the temperature exceeds the standard, it limits the amperage
to prevent the motor from overheating.
Steering Torque
Function
CH-85
Low
Vehicle
Speed
Hi
277CH158