Honda CIVIC 10G 2016 Power Steering Page 1

EPS System Description - EPS Control
Base Current
The base current is a basic current value to drive the motor and is calculated using the steering torque and the vehicle speed.
Inertia Compensation
The torque of the EPS motor tends to be lower as the vehicle begins to move and higher as it decreases in speed due to the inertia of
the rotating body. To reduce the impact of the inertia, the inertia compensation increases the base current in acceleration and
decreases in deceleration. The current of the inertia compensation is calculated by using the steering torque, vehicle speed, and
motor speed.
Damping Compensation
The steering wheel receives vibration from the road surface during braking or cornering. The damping compensation reduces the
vibration of the steering wheel by applying a damping effect through the motor current control. The damping compensation current is
calculated by the steering torque, the vehicle speed, and the motor speed.
Target Current
The target current is a value necessary to perform feedback control of the motor and is determined by applying inertia and damping
compensation to the base current and adding steering torque direction.
Current Feedback Control
Current feedback control monitors the motor current through sensors and reduces any deviation of motor current compared to the
target current, thus accurately running the motor.
Unloader Control
The unloader control reduces motor current at the lock to lock (full right or left) of the steering wheel to protect the system. This value
is determined by using the target current and the motor speed.
Steering Speed Feedback Control
The steering speed feedback control improves stability in the high speed range by controlling the hysteresis of the steering torque.
The steering speed feedback control current is calculated by using the deviation between the target and actual steering angle speed
to adjust to the base current.
Straight Driving Steering Assist
Steering effort is detected and reduced by applying EPS motor assist when driving on a sloped road. This control will return to normal
when no longer driving on a sloped road. This function only operates when the cruise control is on and the speed is set
.
Assist image
EPS Motor Control Circuit
The EPS motor control circuit is composed of a system control CPU, the FET (Field-Effect Transistor) drive circuit, the FET bridge, the
power relay, the fail-safe relays, the electric current detection circuit, relay drive circuit, and the EPS motor. With the signal from the
input sensor, the CPU calculates the appropriate current for the FET drive circuit. This operation is duty controlled.
EPS System Description - EPS Control 1526 http://techinfo.honda.com/rjanisis/pubs/sm/1/2/Contents/enu/61TBAD/...
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Contents Summary of Power Steering

  • Page 1EPS System Description - EPS Control Base Current The base current is a basic current value to drive the motor and is calculated using the steering torque and the vehicle speed. Inertia Compensation The torque of the EPS motor tends to be lower as the vehicle begins to move and higher as it decrease
  • Page 2Motor Output Limit Control The motor output limit control reduces the motor current in the event of repeated turning of the steering wheel when the vehicle is not cardiagn.com in motion. This control gradually reduces power assist force. The power assist force resumes gradually from the steering tor
  • Page 3EPS System Description - Failsafe The EPS control unit diagnoses and monitors the motor system, the torque sensor system, the power supply system, the communication system, and the CPU. When a failure is detected, the EPS indicator comes on and the unit takes one of the following failsafe actions: S
  • Page 4EPS System Description - Motion Adaptive-EPS Control Overview The motion adaptive-EPS control performs the steering torque correction control coordinated with VSA system for stabilizing the vehicle when the steering is unstable. The EPS system determines the state of the vehicle based on the data ca
  • Page 5cardiagn.com Stabilizes Braking on Road Surfaces With Different Friction Coefficients Control When the vehicle behavior is abnormal while braking on an uneven road surface, it compensates for steering torque to enhance vehicle control.
  • Page 6EPS System Description - Overview Overview This vehicle is equipped with electrical power steering (EPS). The driver's steering force is assisted by an electric motor at the steering gearbox, instead of an engine-driven oil pump to generate oil pressure, so the EPS system improves engine efficiency.
  • Page 7EPS System Description - Steering Angle Detection Overview The EPS control unit calculates a steering angle from the motor angle sensor value. The EPS control unit detects the motor rotational angle (A) with the motor angle sensor, and calculates the assist pinion shaft angle (B) by multiplying the
  • Page 8Regular Learning cardiagn.com
  • Page 9The regular learning revises a gap of the neutral position that occurs due to normal wear and tear of the vehicle and a change of the wheel alignment during driving. Learning using the HDS The VSA sensor neutral position memorization for VSA system is performed using the HDS, the steering angle neut
  • Page 10EPS System Description - Steering Gearbox Overview The steering gearbox is dual pinion type, which includes two pinions that are engaged with steering rack. The EPS motor and EPS control unit are gathered into one unit, and are installed on the assist pinion shaft side. The torque sensor which detec
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  • Page 12EPS System Description - System Diagram The steering force of the steering wheel is detected by the torque sensor, and the signal is sent to the EPS control unit. The EPS control unit calculates the assistance torque based on the steering torque signal and vehicle speed signal, and activates the mot
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  • Page 14F-CAN Communication Data EPS System Receiving Signal Transmitting Unit Signal Name PCM Engine speed signal Vehicle speed signal*1 Cruise control status Integrated drive-mode signal*4 Service check signal TCM*2 Vehicle speed signal VSA modulator-control unit Wheel speed signal Vehicle understeering s
  • Page 15EPS System Description - System Diagram The steering force of the steering wheel is detected by the torque sensor, and the signal is sent to the EPS control unit. The EPS control unit calculates the assistance torque based on the steering torque signal and vehicle speed signal, and activates the mot
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  • Page 17F-CAN Communication Data EPS System Receiving Signal Transmitting Unit Signal Name PCM Engine speed signal Vehicle speed signal*1 Cruise control status Integrated drive-mode signal*4 Service check signal TCM*2 Vehicle speed signal VSA modulator-control unit Wheel speed signal Vehicle understeering s
  • Page 18EPS System Description - Torque Sensor Overview The torque sensor is built into the steering gearbox, using a Hall IC sensor to detect steering wheel torque forces. The torque sensor consists of the input shaft, the torsion bar, the manual pinion shaft, and the torque sensor unit. cardiagn.com
  • Page 19How to Troubleshoot the EPS System Indicator This system has one (without LKAS (Lane Keep Assist System)) or two (with LKAS) indicators on the gauge control module. NOTE: For locations of each indicator, refer to gauge control module component location index. EPS Indicator Under normal conditions, t
  • Page 20Repeated extreme steering force, such as turning the steering wheel continuously back-and-forth with the vehicle stopped, causes an increase in electrical current draw by the EPS motor. The increase of electric current causes the EPS motor and EPS control unit to heat up. Because this heat adversely
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  • Page 224. Follow the prompts on the HDS to display the DTC(s) on the screen. After determining the DTC, refer to the DTC troubleshooting. Do the all systems DTC check, and troubleshoot any powertrain DTCs first. 5. Turn the vehicle to the OFF (LOCK) mode. How to Clear DTCs 1. With the vehicle in OFF (LOCK)
  • Page 23Power Steering Assist Check 1. Power Steering Assist - Check NOTE: This test should be done with original equipment tires and wheels at the correct tire pressure. 1. Start the engine, and let it idle. 2. Attach a commercially available spring scale (A) to the steering wheel. With the engine idling a
  • Page 24EPS Circuit Diagram cardiagn.com
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  • Page 26EPS Circuit Diagram cardiagn.com
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  • Page 28EPS Component Location Index cardiagn.com
  • Page 29EPS Control Unit Connector for Inputs and Outputs EPS Control Unit Connector for Inputs and Outputs Connector Index EPS Control Unit Connector A (2P) EPS Control Unit Connector B (6P) EPS Control Unit Connector C (4P) EPS Control Unit Connector A (2P) cardiagn.com Terminal Terminal sign Description
  • Page 30*1: Without LKAS *2: With LKAS cardiagn.com
  • Page 31Terminal Terminal sign Description number 6 Not used ――― *1: Without LKAS *2: With LKAS EPS Control Unit Connector C (4P) cardiagn.com Terminal Terminal sign Description number 1 T/S GND Ground for the torque sensor 2 T/S VDD Power source for torque sensor 3 TSM Detects torque sensor main signal 4 T
  • Page 32EPS Control Unit Update Special Tool Required Image Description/Tool Number MVCI unit with the latest control module (CM) update software installed cardiagn.com 1. EPS Control Unit - Update NOTE: Check any official Honda service website for more service information about updating the MVCI and contro
  • Page 33EPS DTC Troubleshooting Index DTC Detection Item C0037 -F0 Left Rear Wheel Speed Sensor Malfunction C003A -F0 Right Rear Wheel Speed Sensor Malfunction C0062 -96 Longitudinal Acceleration Sensor Malfunction C0063 -96 Yaw-Rate Sensor Malfunction C1400 -11 Motor Current Malfunction -13 EPS Motor Circu
  • Page 34EPS Motor/Control Unit Removal and Installation NOTE: Do not allow dust, dirt, or other foreign materials to enter the steering gearbox. 1. Vehicle - Lift 2. Engine Undercover - Remove 3. Power Steering Heat Shield - Remove cardiagn.com 4. Connectors (EPS Motor) - Disconnect
  • Page 35cardiagn.com 5. EPS Motor/Control Unit - Remove 1. If necessary, remove the rubber bush (A) and motor bush (B). 2. Remove the O-ring (C). NOTE: Do not allow dust, dirt, or other foreign materials to enter the steering gearbox. 1. EPS Motor/Control Unit - Install
  • Page 361. Apply steering grease to the new O-ring (A). 2. If the rubber bush (B) and motor bush (C) removed, apply steering grease to the rubber bush and motor bush, then install them to the EPS motor/control unit (D). NOTE: Check the rubber bush and motor bush for damage and cracks. If the rubber bush and
  • Page 371. Loosely install the heat shield (A), then tighten the mounting bolts to the specified torque in the sequence shown. cardiagn.com 4. Engine Undercover - Install 5. EPS Control Unit Software - Check 1. Make sure the EPS control unit has the latest software. If it does not have the latest, update th
  • Page 38EPS Symptom Troubleshooting - EPS indicator does not go off cardiagn.com
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  • Page 40EPS indicator does not go off NOTE: The indicator comes on when the reprogramming fails. Do the reprogramming of the EPS control unit again. 1. Problem verification: ‐1. Start the engine. ‐2. Check the EPS indicator. Does the EPS indicator come on, then go off? YES Intermittent failure, the system i
  • Page 41‐1. Turn the vehicle to the OFF (LOCK) mode. ‐2. Check the following fuse. Fuse No. A2-1 (70 A) Location Under-hood fuse/relay box Is the fuse OK? YES The fuse is OK. Reinstall the fuse, then go to step 6. NO Replace the fuse. If the fuse blows again, repair a short to ground in the No. A2-1 (70A) f
  • Page 42Is there battery voltage? YES The +B EPS wire is OK. Go to step 9. NO Repair an open in the wire between the EPS motor/control unit and the No. A2-1 (70A) fuse.■ 9. Open wire check (GND line): ‐1. Check for continuity between test points 1 and 2. Test condition Vehicle OFF (LOCK) mode EPS control un
  • Page 43Is there continuity? YES The F-CAN B_H and F-CAN B_L wires are OK. Check for poor connections or loose terminals at the CAN gateway and the EPS control unit connector. Check for any authorized service information related to the DTCs or symptoms you are troubleshooting. If they are OK, replace the EP
  • Page 44EPS Symptom Troubleshooting - EPS indicator does not go off cardiagn.com EPS indicator does not go off NOTE: The indicator comes on when the reprogramming fails. Do the reprogramming of the EPS control unit again. 1. Problem verification: ‐1. Start the engine. ‐2. Check the EPS indicator. Does the E
  • Page 45YES Intermittent failure, the system is OK at this time.■ NO Go to step 2. 2. DTC's check: ‐1. Check for DTCs with the HDS. DTC Description DTC Freeze Frame Are there DTCs indicated? YES Go to indicated DTC's troubleshooting.■ NO Go to step 3. 3. Gauge control module operation check: ‐1. Do the gaug
  • Page 46‐3. Measure the voltage between test points 1 and 2. Test condition Vehicle ON mode EPS control unit connector B (6P): disconnected Test point 1 EPS control unit connector B (6P) No. 5 Test point 2 Body ground Is there battery voltage? YES The IG1 VSA/ABS wire is OK. Go to step 7. NO Repair an open
  • Page 47Gauge control module connector A (32P): disconnected Test point 1 EPS control unit connector B (6P) No. 3 Test point 2 Gauge control module connector A (32P) No. 19 Test point 1 EPS control unit connector B (6P) No. 1 Test point 2 Gauge control module connector A (32P) No. 20 Is there continuity? YE
  • Page 48EPS Symptom Troubleshooting - Steering pull Steering pull 1. EPS system check: ‐1. Turn the vehicle to the ON mode. ‐2. Disconnect the following connectors. EPS control unit connector A (2P) EPS control unit connector B (6P) ‐3. Test-drive the vehicle. cardiagn.com Is there steering pull? YES Make s
  • Page 49EPS Symptom Troubleshooting Index When the vehicle has one of these symptoms, check for a diagnostic trouble code (DTC) with the HDS. If there is no DTC, do the diagnostic procedure for the symptom, in the sequence listed, until you find the cause. Symptom Diagnostic Procedure Also check for HDS doe