How to Troubleshoot the Collision Mitigation Braking System (CMBS)
How to Troubleshoot the Collision Mitigation Braking System (CMBS)
CMBS Indicator
When the system is OK, the CMBS indicator comes on for about 2 seconds after pressing the engine start/stop button to select the ON mode, then it goes off.
The CMBS indicator comes on when the ACC unit detects a problem in the system.
NOTE:
- The ACC indicator indicates problems related with the ACC system and the CMBS.
- The CMBS indicator only indicates its system problems.
- The CMBS works with related systems such as the VSA system. If these related systems have a problem, the CMBS does not operate. In this case, the CMBS indicator and the related system indicator come on.
When a problem is detected by the self-diagnostic function, the CMBS stops operating, turns on the CMBS indicator, indicates the problem on the MID, and stores the DTC.
CMBS OFF Switch
Press and hold the CMBS OFF switch for at least 1 second to turn the CMBS off and on.
CMBS Indication
- When the system is OK, the CMBS indicator comes on for 2 seconds after press the engine start/stop button to select the ON mode with the CMBS OFF switch on.
- When the system is activated, the word BRAKE is indicated on the MID and the warning buzzer sounds.
- First stage, BRAKE indicator and buzzer
- Second stage, BRAKE indicator, buzzer, light braking, and light seat belt tension
- Third stage, BRAKE indicator, buzzer, strong braking, and strong seat belt tension
- If the system stops operating because of a problem, the MID indicates the problem.
ACC Unit
The ACC unit controls the brakes and the various driver warnings when the system recognizes the possibility of a collision.
The ACC unit has a self-diagnostic function. If the system detects a problem, it stops the CMBS, and turns on the CMBS indicator.
CMBS Initial Check
The ACC unit turns on the CMBS indicator if the CMBS initial check is not completed.
NOTE: For proper CMBS operation, if the ACC unit or the VSA modulator-control unit is replaced, do the CMBS initial check incomplete troubleshooting (DTC 100) 100.
Millimeter Wave Radar
The millimeter wave radar calculates the distance between the moving vehicle ahead and your vehicle, and detects the two vehicles' speed differential.
The ACC unit receives this information from the millimeter wave radar.
The millimeter wave radar also has an error detection function, and it sends a signal to the ACC unit if an error is detected.
How to Troubleshoot DTCs
Check and clear the DTCs with the HDS.
NOTE: When both the ACC and CMBS indicators come on, do the ACC system troubleshooting first (except DTC 100).
Before troubleshooting, check and note these items:
- Ask the client about the conditions when the problem occurred, and try to reproduce the same conditions for troubleshooting.
- If the symptom does not appear and the CMBS indicator does not come on during the test-drive, but troubleshooting is done based on the DTC, check for poor connections or loose terminals at all connectors related to the circuit that you are troubleshooting.
- After the troubleshooting, or repairs are done, clear the DTCs, and test-drive the vehicle under the same conditions as when the DTC was originally set. Make sure the CMBS indicator does not come on.
- The ACC system and the CMBS may sometimes stop control because of the environment (weather, road conditions, driving conditions, etc.). A DTC may be stored in these cases.
DTCs may be stored even when the system is OK:
NOTE: The ACC indicator will not come on, but the CMBS indicator does come on when the following DTCs are stored.
DTC 88: Millimeter Wave Radar Out of Detection Condition
The millimeter wave radar overheats, the power supply voltage for the millimeter wave radar is low, or there is a communication error between the ACC unit and the millimeter wave radar.
DTC 95: Power Supply Voltage Too High
DTC 96: Power Supply Voltage Too Low
DTC 97: CMBS Offset Cancel Timeout
Extensive driving on a rough road or the pressing the engine start/stop button to select the OFF mode when the vehicle is driving.
DTC 102: CMBS Parking Brake Incomplete Releasing
Parking brake not fully released, or driving with the parking brake stuck.
How to Retrieve DTCs
NOTE: Make sure the battery is fully charged before you begin.
1. Press the engine start/stop button to select the OFF mode.
2. Connect the HDS (Honda Diagnostic System) to the data link connector (DLC) (A) located under the driver's side of the dashboard.
3. Press the engine start/stop button to select the ON mode.
4. Make sure the HDS communicates with the vehicle and the ACC unit. If it does not communicate, go to the DLC circuit troubleshooting Testing and Inspection.
5. Use the HDS to check for CMBS DTCs.
6. Read and record the DTC.
7. Press the engine start/stop button to select the OFF mode, then wait for 10 seconds.
8. Disconnect the HDS from the DLC.
9. Do the troubleshooting procedure for the DTC.
How to Clear DTCs
NOTE: Make sure the battery is fully charged before you begin.
1. Press the engine start/stop button to select the OFF mode.
2. Connect the HDS (Honda Diagnostic System) to the data link connector (DLC) (A) located under the driver's side of the dashboard.
3. Press the engine start/stop button to select the ON mode.
4. Make sure the HDS communicates with the vehicle and the ACC unit. If it does not communicate, go to the DLC circuit troubleshooting Testing and Inspection.
5. In the DRIVING SUPPORT MENU of the HDS, select ACC, then DTCs choose the clear DTCs icon, and follow the prompts.
6. Press the engine start/stop button to select the OFF mode, then wait for 10 seconds.
7. Disconnect the HDS from the DLC.