Power Steering System Troubleshooting & Testing: Diagnosis Honda Civic IX

Diagnostic Trouble Code (DTC)

1. If the CPU cannot be activated, or it fails, the EPS indicator comes on, but no EPS DTC is stored.
2. The memory can hold any number of DTCs. However, when the same DTC is detected more than once, the most recent DTC is written over the prior DTC, therefore only one occurrence is stored.
3. The lowest DTC is indicated first. The DTCs are indicated in ascending order, not in the order that they occurred.
4. The DTCs are stored in the EEPROM (non-volatile memory) therefore the stored DTCs cannot be erased by disconnecting the battery. Do the specified procedures to clear the DTCs.

Self-Diagnosis

Self-diagnosis can be classified into three categories

1. Initial diagnosis: Done right after the engine starts and until the EPS indicator goes off.
2. Regular diagnosis: Done right after the initial diagnosis until the ignition switch is turned to LOCK (0).
3. Steering diagnosis: Done during regular diagnosis while turning steering wheel.

The EPS control unit does the following functions when a problem is detected by self-diagnosis

1. Turns on the EPS indicator.
2. Stores the DTC.
3. Stops or restricts power assist and manual steering operation resumes.

Note. For DTCs 11-01, 11-02, 12-01, 21-01, 21-02, 22-01, 35-04, 71-01, and 71-03, the EPS indicator will go off automatically, and the system returns to normal.

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 battery is in good condition and fully charged.

Scheme 107

1. If the system indicators stay on, connect the HDS to the data link connector (DLC) (A) located under the driver's side of the dashboard.
2. Turn the ignition switch to ON (II).
3. Make sure the HDS communicates with the vehicle and the EPS control unit. If it does not, go to the DLC circuit troubleshooting See DLC CIRCUIT TROUBLESHOOTING (EXCEPT K24Z7) or DLC CIRCUIT TROUBLESHOOTING (K24Z7) .
4. Check the diagnostic trouble code (DTC) and note it. Then refer to the indicated DTC's troubleshooting, and do the appropriate troubleshooting procedure.

Note. The HDS reads the DTC, the current data, and other system data. For specific operations, refer to the Help menu that came with the HDS.