How to Troubleshoot the ABS

System Indicator

This system has two indicators:

ABS indicator (A)
Brake system indicator (B)

When the system detects a problem, it will turn the appropriate indicators on. Depending on the failure, the ABS modulator-control unit determines which indicators are turned on.
When the system is OK, each indicator comes on for about 2 seconds after turning the ignition switch ON (II), then goes off.

ABS indicator

ABS indicator comes on, when ABS function is lost. The brakes still work like a conventional system.

Brake system indicator

Brake system indicator comes on, when EBD function is lost, the parking brake is applied, and/or the brake fluid level is low.

ABS indicator goes off

Each indicator will go off after a problem goes away, but the timing which the ABS modulator-control unit turns off the indicator varies between DTCs.

The indicators go off automatically when the system returns to normal.
The indicators stay on until the ignition switch is turned OFF whether or not the system returns to normal.
The indicators stay on until the vehicle is driven after the system returns to normal.

Diagnostic Trouble Code (DTC)

The memory can hold all DTCs. However, when the same DTC is detected more than once, the more recent DTC is written over the earlier one. Therefore, when the same problem is detected repeatedly, it is memorized as a single DTC.
The DTCs are indicated in the order they occur.
The DTCs are memorized in the EEPROM. Therefore, the memorized DTCs cannot be canceled by disconnecting the battery. Do the specified procedures to clear the DTCs.

Self-diagnosis

Self-diagnosis can be classified into two categories:
- Initial diagnosis: Done right after the ignition switch is turned ON (II) and until the ABS indicator goes off.
- Regular diagnosis: Done right after the initial diagnosis until the ignition switch is turned OFF.
When the system detects a problem, the ABS modulator-control unit shifts to fail-safe mode.

Kickback

The pump motor operates when the ABS modulator-control unit is functioning, and the fluid in the reservoir is forced out to the master cylinder, causing kickback at the brake pedal.

Pump Motor

The pump motor operates when the ABS modulator-control unit is functioning.
The ABS modulator-control unit checks the pump motor operation during regular diagnosis when the vehicle is driven over 15 km/h (10 mph) the first time after the ignition switch is turned ON (II). You may hear the motor operate at this time, but it is normal.

Brake Fluid Replacement/Air Bleeding

Brake fluid replacement and air bleeding procedures are identical to the procedures used on vehicles not equipped with ABS.

How to Troubleshoot DTCs

The troubleshooting procedures assumes that the cause of the problem is still present and the ABS indicator is still on. Following the flowchart when the ABS code does not return after clearing 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 ABS indicator came on, such as during control, after control, when vehicle was travelling at a certain speed, etc.

2. When the ABS indicator does not come on during the test-drive, but troubleshooting is done based on the DTC, check for loose connectors, poor contact of the terminals, etc. before you start troubleshooting.

3. After troubleshooting, or repairs are done, clear the DTCs, and test-drive the vehicle under the same conditions as originally set with the DTCs. Make sure the ABS indicator does not come on.

4. Check for other unit DTCs which connected via F-CAN, if there are DTCs that are related to F-CAN, the most likely cause was that the ignition switch was turned ON (II) with the ABS modulator-control unit connector disconnected. Clear the DTCs. Check for PGM-FI and ABS codes, and troubleshoot those first.

Intermittent Failures

The term ‘‘intermittent failure'' means a system may have had a failure, but it checks OK now. If the indicator(s) of the system on the dash do es not come on, check for poor connections or loose pins at all connectors related to the circuit that you are troubleshooting. If the indicators were on but then went out, the original problem may have been intermittent.

How to Use the HDS (Honda Diagnostic System)

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 ON (II).

3. Make sure the HDS communicates with the vehicle and the ABS modulator-control unit. If it doesn't, troubleshoot the DLC circuit: R18A1 engine model, K20Z2 engine model.

4. Check the diagnostic trouble code (DTC) and note it. Also check the on board snapshot data, and download any data found. Then refer to the indicated DTC's troubleshooting, and begin the appropriate troubleshooting procedure.

NOTE:
The HDS communication will be stopped when the vehicle speed is at 50 km/h (31 mph) or more.
The HDS can read the DTC, current data, and other system data.
For specific operations, refer to the Help menu that came with the HDS.

How to Retrieve DTCs

1. With the ignition switch OFF, connect the HDS to the 16P data link connector (DLC) under the driver's side of the dashboard.

2. Turn the ignition switch ON (II).

3. Make sure the HDS communicates with the vehicle and the ABS modulator-control unit. If it doesn't, troubleshoot the DLC circuit: R18A1 engine model, K20Z2 engine model.

4. Follow the prompts on the HDS to display the DTC(s) on the screen. After determining the DTC, refer to the DTC troubleshooting.

5. Turn the ignition switch OFF.

How to Clear DTCs

1. With the ignition switch OFF, connect the HDS to the 16P data link connector (DLC) under the driver's side of the dashboard.

2. Turn the ignition switch ON (II).

3. Make sure the HDS communicates with the vehicle and the ABS modulator-control unit. If it doesn't, troubleshoot the DLC circuit: R18A1 engine model, K20Z2 engine model.

4. Clear the DTC(s) by following the screen prompts on the HDS.

5. Turn the ignition switch OFF.