HOW TO TROUBLESHOOT THE EPS
EPS Indicator
Under normal conditions, the EPS indicator (A) comes on when turning the vehicle to the ON mode, then goes off after the engine is started. This indicates that the LED and its circuit are operating correctly.
If there is a failure in the system after the engine is started, the EPS indicator will stay on and stores a DTC, and the power assist is turned off or restricted.
The EPS indicator will stay on until the DTC is erased. When a problem is detected the EPS indicator comes on.
There are cases when the indicator stays on until turning the vehicle to the OFF (LOCK) mode, and cases when the indicator goes off automatically when the system returns to normal. Even though the system is operating normally, the EPS indicator will come on under some conditions; for example if the vehicle is stopped with the engine at high speed, and a constant input from the steering wheel.
To determine the actual cause of the problem, question the customer about the conditions during which the problem occurred, taking the above conditions into consideration.
Diagnostic Trouble Code (DTC)
Self-Diagnosis
Self-diagnosis can be classified into three categories:
Restriction on Power Assist Operation
Repeated 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 affects the system, the control unit monitors the electric current draw of the EPS motor.
When the control unit detects heat build-up in the EPS motor, it reduces the electric current to the EPS motor gradually to protect the system, and it restricts the power assist operation. The EPS indicator does not come on during this function.
When steering torque is not applied to the steering wheel, or when turning the vehicle to the OFF (LOCK) mode and the EPS motor cools, the control unit will restore the power assist gradually until it's fully restored (after about 30 minutes).
How to Troubleshoot DTCs
The troubleshooting procedures assume that the cause of the problem is still present and the EPS indicator is still on. Following the procedure when the EPS indicator does not come on can result in incorrect diagnosis.
1. Question the customer about the conditions when the problem occurred, and try to reproduce the same conditions for troubleshooting. Find out when the EPS indicator came on, such as while turning, after turning, when the vehicle was at a certain speed, etc
2. When the EPS indicator does not come on during the test-drive, but troubleshooting is done based on the DTC, check for loose connectors, poor terminal contact, etc., in the affected circuit before you start troubleshooting
3. After troubleshooting, clear the DTC and test-drive the vehicle. Be sure the EPS indicator does not come on.
How to Use the HDS (Honda Diagnostic System)
NOTE: Make sure the 12 volt battery is in good condition and fully charged.
1. If the system indicator(s) stay on, connect the HDS to the data link connector (DLC) (A) located under the driver's side of the dashboard.
2. Turn the vehicle to the ON mode.
3. Make sure the HDS communicates with the vehicle and the EPS control unit. If it does not, go to the DLC circuit troubleshooting.
4. Check the diagnostic trouble code (DTC) and the freeze data, for all systems, troubleshoot the powertrain DTCs first. Then refer to the indicated DTC's troubleshooting, and do the appropriate troubleshooting procedure.
NOTE:
How to Retrieve DTCs
1. With the vehicle in OFF (LOCK) mode, connect the HDS to the data link connector (DLC) located under the driver's side of the dashboard.
2. Turn the vehicle to the ON mode.
3. Make sure the HDS communicates with the vehicle and the EPS control unit. If it does not, go to the DLC circuit troubleshooting.
4. 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) mode, connect the HDS to the data link connector (DLC) located under the driver's side of the dashboard.
2. Turn the vehicle to the ON mode.
3. Make sure the HDS communicates with the vehicle and the EPS control unit. If it does not, go to the DLC circuit troubleshooting.
4. Clear the DTC(s) by following the screen prompts on the HDS.
5. Turn the vehicle to the OFF (LOCK) mode.