Reading and Clearing Diagnostic Trouble Codes
How to Troubleshoot the Advanced Hydraulic Booster
NOTICE
A serious advanced hydraulic booster problem will decrease the braking power of the vehicle, and increase the risk of a collision.
If the system indicators come on and the buzzer sounds while driving, stop the vehicle in a safe place as soon as possible, and do not drive the vehicle until the system returns to normal.
System Indicators
This system has two indicators and a buzzer:
- AHB indicator (A) (amber color)
- Brake system indicator (B) (red color)
- Buzzer (audible alert)
When the system detects a problem, it turns on the AHB indicator and buzzer, and/or the brake system indicator. Depending on the failure, the servo unit determines which indicators are turned on.
When the system is OK, the AHB indicator and brake system indicator come on for about 2 seconds after turning the ignition switch to ON (II), then they go off.
AHB Indicator
The AHB indicator comes on when the advanced hydraulic booster function is lost, and this may affect normal brake operation.
If AHB indicator comes on, press the brake pedal slowly, and check the braking effectiveness then stop the vehicle and inspect above system.
Brake System Indicator
The brake system indicator comes on when the advanced hydraulic booster function is lost, the EBD function is lost, the parking brake is applied, and/or the brake fluid level is low.
Buzzer
The buzzer indicates audibly, in conjunction with the brake system indicator, when the advanced hydraulic booster function is lost, and this may affect normal brake operation.
Diagnostic Trouble Code (DTC)
- The memory holds 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 ascending number order, not in the order they occur.
- The DTCs are memorized in the EEPROM. Therefore, the memorized DTCs cannot be erased 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 to ON (II) and until the AHB indicator and the brake system indicator go off.
- Regular diagnosis: Done right after the initial diagnosis until the ignition switch is turned to LOCK (0).
- When the system detects a problem, the servo unit shifts to fail-safe mode.
Pump Motor
- The pump motor in the power unit operates when the accumulator inner pressure becomes low while the ignition switch is turned to ON (II).
- The pump motor is operated by the servo unit. The servo unit has independent main activation and subactivation circuits in the ECU (electric control unit). If either circuit has a problem, the other one will run the pump motor.
Brake Fluid Replacement/Air Bleeding
Brake fluid replacement and air bleeding procedures for the servo unit and power unit are independent of the conventional brake system. Service and Repair
How to Troubleshoot DTCs
The troubleshooting procedures assume that the cause of the problem is still present, and the AHB and/or brake system indicator is still on. Following a troubleshooting procedure for a code that has been cleared but does not reset 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 AHB and/or brake system indicator came on, such as during activation, after activation, when the vehicle was traveling at a certain speed, etc. If necessary, have the customer demonstrate the concern.
2. When the AHB and/or brake system 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. in the circuit indicated by the DTC before you start troubleshooting.
3. After troubleshooting, or repairs are done, clear the DTCs, and test-drive the vehicle under the same conditions that originally set the DTCs. Make sure the AHB and/or brake system indicators do not come on.
4. Check for DTCs from other systems which are connected via F-CAN. If there are DTCs that are related to F-CAN, one possible cause was that the ignition switch was turned to ON (II) with the servo unit connector disconnected. Clear the DTCs. Check for fuel and emissions DTC's first.
NOTE: Always troubleshoot fuel and emissions DTC's first.
Intermittent Failures
The term "intermittent failure" means a system may have had a failure, but it checks OK now. If you cannot reproduce the condition, check for loose connectors or terminal pins related to the circuit that you are troubleshooting.
How to Use the HDS (Honda Diagnostic System)
1. If the AHB indicator and the brake system indicator 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 servo unit. If it doesn't, troubleshoot the DLC circuit. Testing and Inspection
4. Check the diagnostic trouble code (DTC) for all systems, troubleshoot the powertrain DTCs first and note it. Then refer to the indicated DTC's troubleshooting, and do the appropriate troubleshooting procedure.
NOTE:
- The HDS can read the DTC, the 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 in LOCK (0), connect the HDS to the data link connector (DLC) 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 servo unit. If it doesn't, troubleshoot the DLC circuit. Testing and Inspection
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 ignition switch to LOCK (0).
How to Clear DTCs
1. With the ignition switch in LOCK (0), connect the HDS to the data link connector (DLC) 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 servo unit. If it doesn't, troubleshoot the DLC circuit. Testing and Inspection
4. Clear the DTC(s) by following the screen prompts on the HDS.
5. Turn the ignition switch to LOCK (0).