Adaptive Cruise Control (ACC) System Troubleshooting (No DTC Indication)
Adaptive Cruise Control (ACC) System Troubleshooting (No DTC Indication)
1. Check the TECH (10 A) fuse in the auxiliary under-hood fuse/relay box.
Is the fuse OK?
YES -
Go to step 2.
NO -
Replace the fuse, and recheck.�
2. Test the TECH relay Power Relay Test.
Is the relay OK?
YES -
Go to step 3.
NO -
Replace the relay, and recheck.�
3. Disconnect the ACC unit 20P connector.
4. Turn the ignition switch to ON (II).
5. Measure the voltage between ACC unit 20P connector terminal No. 2 and body ground.
There should be battery voltage.
Is there battery voltage?
YES -
Go to step 6.
NO -
Repair an open in the wire between the TECH relay in the auxiliary under-hood fuse/relay box and the ACC unit. If the wire is OK, replace the auxiliary under-hood fuse relay box.�
6. Turn the ignition switch to LOCK (0).
7. Measure the resistance between body ground and ACC unit 20P connector terminals No. 9, No. 11, and No. 12 individually. There should be less than 1.0 Ohms.
Is the resistance as specified?
YES -
The system is OK at this time. Go to the appropriate step according to these symptoms:
- If the ACC system detects a vehicle driving in another lane, go to step 8.
- If the ACC system does not detect the vehicle driving ahead, go to step 12.
- If the ACC system does not detect the vehicle driving ahead consistently, go to step 22.
NO -
Repair an open in the wire or poor ground (G401).�
8. Check the vehicle's history for front end collision repairs.
Has the vehicle been in a collision and repaired?
YES -
Go to step 9.
NO -
Go to step 10.
9. Check if the millimeter wave radar and the main bracket are installed correctly, and also check if the vehicle frame is straight.
Are all parts installed correctly?
YES -
Aim the millimeter wave radar Adjustments.�
NO -
Reinstall the part correctly, or if damaged, replace the part, then aim the millimeter wave radar Adjustments.�
10. Check the wheel alignment Service and Repair.
Is the wheel alignment OK?
YES -
Go to step 11.
NO -
Adjust the wheel alignment.�
11. Find out when the system has misdetections.
Do they occur within 20 minutes or less?
YES -
Go to step 12.
NO -
Explain to the client that system misdetections are sometimes caused by the environment (weather, road conditions, driving conditions, etc.).�
12. Find out if the detection problem occurs only with certain types of vehicles (dirty vehicle, tall vehicle, motorcycle, or special vehicle).
Does it occur only with certain types of vehicles?
YES -
Explain to the client that the system sometimes cannot detect certain vehicle types.�
NO -
Go to step 13.
13. Check for dirt, dust, or snow on the surface of the millimeter wave radar and the front radar cover.
Are the radar and front radar cover OK?
YES -
Go to step 14.
NO -
Clean the radar and the front radar cover.�
14. Check if there was a heavy load in the trunk.
Was there a heavy load in the trunk?
YES -
Remove the heavy load from the trunk. Advise the customer that this problem may occur temporarily when hauling loads.�
NO -
Go to step 15.
15. Measure the front and rear vehicle ride height.
Is the vehicle ride height equal?
YES -
Go to step 16.
NO -
Inspect the suspension for damage, and compare ride height to a known-good vehicle. Adjust the wheel alignment as needed Service and Repair.�
16. Find out if the detection problem occurs only on a particular road such as a winding road, an entrance of a corner, an exit of a corner, a tight corner, or a bad road.
Does it occur only on a particular road?
YES -
Explain to the client that the system sometimes cannot detect under certain road conditions.�
NO -
Go to step 17.
17. Find out if the detection problem occurs only under poor weather conditions such as fog, snow, heavy rain, or gusty winds.
Does it occur only under poor weather conditions?
YES -
Explain to the client that the system sometimes cannot detect under poor weather conditions.�
NO -
Go to step 18.
18. Find out if the detection problem occurs only when the vehicle ahead drives under these conditions:
- driving in a zigzag line.
- merged into the lane suddenly.
- closing on a vehicle within 13 ft (4 m).
Does it occur only under certain driving conditions?
YES -
Explain to the client that the system sometimes cannot detect under certain driving conditions.�
NO -
Go to step 19.
19. Find out if the detection problem occurs under all conditions.
Does it occur under all conditions?
YES -
The millimeter wave radar vertical aiming is incorrect. Readjust the aiming.�
NO -
Go to step 20.
20. Confirm if the radar detects vehicles driving in another lane.
Does it detect vehicles in other lanes?
YES -
The millimeter wave radar horizontal aiming is incorrect. Readjust the aiming.�
NO -
Go to step 21.
21. Confirm if the detection problem is caused by instability.
NOTE: If the cause of the misdetection or undetectable problems is unclear, it is possible that the problem was caused by environmental conditions. Explain to the client that intermittent failures are sometimes caused by environmental conditions.
Is the vehicle unstable? (Compare it to a known-good, like vehicle.)
YES -
Check the other components such as the yaw rate-lateral/longitudinal acceleration sensor or wheel sensors, etc.�
NO -
The system is OK at this time.�
22. Check for dirt, dust, or snow on the surface of the millimeter wave radar and the front radar cover.
Are the radar and the front radar cover OK?
YES -
Go to step 23.
NO -
Clean the radar and the front radar cover.�
23. Check the vehicle's history for front end collision repairs.
Has the vehicle been repaired?
YES -
Go to step 24.
NO -
Go to step 25.
24. Check if the millimeter wave radar and the main bracket are installed correctly, and also check if the vehicle frame is straight.
Are all parts installed correctly?
YES -
Aim the millimeter wave radar Adjustments.�
NO -
Reinstall the part correctly, or if damaged, replace the part, then aim the millimeter wave radar Adjustments.�
25. Check if there was a heavy load in the trunk.
Was there a heavy load in the trunk?
YES -
Remove the heavy load from the trunk. Advise the client that this problem may occur temporarily when hauling loads.�
NO -
Go to step 26.
26. Measure the front and rear vehicle ride height.
Is the vehicle ride height equal?
YES -
Go to step 27.
NO -
Adjust the wheel alignment Service and Repair.�
27. Find out if the detection problem occurs only with certain types of vehicles (dirty vehicle, tall vehicle, motorcycle, or special vehicle).
Does it occur only with certain types of vehicles?
YES -
Explain to the client that the system sometimes cannot detect certain vehicle types.�
NO -
Go to step 28.
28. Find out if the detection problem occurs only on a particular road such as a winding road, an entrance of a corner, an exit of a corner, a tight corner, or a bad road.
Does it occur only on a particular road?
YES -
Explain to the client that the system sometimes cannot detect under certain road conditions.�
NO -
Go to step 29.
29. Find out if the detection problem occurs only under poor weather conditions such as fog, snow, heavy rain, or gusty winds.
Does it occur only under poor weather conditions?
YES -
Explain to the client that the system sometimes cannot detect under poor weather conditions.�
NO -
Go to step 30.
30. Find out if the detection problem occurs only when the vehicle ahead drives under these conditions:
- driving in a zigzag line.
- merged into the lane suddenly.
- closing on a vehicle within 13 ft (4 m).
Does it occur only under certain driving conditions?
YES -
Explain to the client that the system sometimes cannot detect under certain driving conditions.�
NO -
Go to step 31.
31. Find out if the detection problem occurs under all conditions.
Does it occur under all conditions?
YES -
The millimeter wave radar vertical aiming is incorrect. Readjust the aiming.�
NO -
Go to step 32.
32. Confirm if the radar detects vehicles driving in another lane.
Does it detect vehicles in other lanes?
YES -
The millimeter wave radar horizontal aiming is incorrect. Readjust the aiming.�
NO -
Go to step 33.
33. Confirm if the detection problem is caused by vehicle instability.
NOTE: If the cause of the misdetection or undetectable problems is unclear, it is possible that the problem was caused by many environmental conditions. Explain to the customer that intermittent failures are sometimes caused by environmental conditions.
Is the vehicle unstable? (Compare it to a known-good, like vehicle)
YES -
Check the other components such as the yaw rate-lateral/longitudinal acceleration sensor or wheel sensors, etc.�
NO -
The system is OK at this time.�