Adaptive Cruise Control (ACC) System Troubleshooting (No DTC Indication)
Adaptive Cruise Control (ACC) System Troubleshooting (No DTC Indication)
1. Check the No. 29 (7.5 A) fuse in the driver's under-dash fuse/relay box.
Is the fuse OK?
YES -
Go to step 2.
NO -
Check for a short in the wire between the No. 29 (7.5 A) fuse socket and the ACC unit. If OK, replace the fuse.
2. Disconnect the ACC unit 20P connector.
3. Turn the ignition switch to ON (II).
4. Measure the voltage between ACC unit 20P connector terminal No. 2 and body ground.
Is there battery voltage?
YES -
Go to step 5.
NO -
Repair an open in the wire between the No. 29 (7.5 A) fuse in the driver's under-dash fuse/relay box and the ACC unit.
5. Turn the ignition switch to LOCK (0).
6. Check for continuity between body ground and the ACC unit 20P connector terminals No. 9, No. 11 and No. 12 individually.
Is there continuity?
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 7.
- If the ACC system does not detect the vehicle driving ahead, go to step 11.
- If the ACC system does not detect the vehicle driving ahead consistently, go to step 21.
NO -
Repair an open in the wire or poor ground (G401) (Starter Cable, Battery/Engine/Transmission Ground Cable).
7. Check the vehicle's history for front end collision repairs.
Has the vehicle been repaired?
YES -
Go to step 8.
NO -
Go to step 9.
8. 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.
9. Check the wheel alignment Service and Repair.
Is the wheel alignment OK?
YES -
Go to step 10.
NO -
Adjust the wheel alignment.
10. Find out when the system has misdetections.
Do they occur within 20 minutes or less?
YES -
Go to step 11.
NO -
Explain to the client that system misdetections are sometimes caused by the environment (weather, road conditions, driving conditions, etc.).
11. 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 12.
12. 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 13.
NO -
Clean the radar and the front radar cover.
13. 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. Advice the client that this problem may occur temporarily when hauling loads.
NO -
Go to step 14.
14. Measure the front and rear vehicle ride height.
Is the vehicle ride height equal?
YES -
Go to step 15.
NO -
Inspect the suspension for damage, and compare ride height to a known-good vehicle. Adjust the wheel alignment as needed Service and Repair.
15. Find out if the detection problem occurs only on a particular road such as a winding road, an entrance of a corner, 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 16.
16. 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 17.
17. 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 18.
18. 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 19.
19. 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 20.
20. 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 many 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-acceleration sensor or the wheel sensors, etc.
NO -
The system is OK at this time.
21. Check for dirt, dust, or snow on the surface of the millimeter wave radar and the emblem.
Are the radar and the emblem OK?
YES -
Go to step 22.
NO -
Clean the radar and the emblem.
22. Check the vehicle's history for front end collision repairs.
Has the vehicle been repaired?
YES -
Go to step 23.
NO -
Go to step 24.
23. 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.
24. 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. Advice the client that this problem may occur temporarily when hauling loads.
NO -
Go to step 25.
25. Measure the front and rear vehicle ride height.
Is the vehicle ride height equal?
YES -
Go to step 26.
NO -
Adjust the wheel alignment Service and Repair.
26. 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 27.
27. Find out if the detection problem occurs only on a particular road such as a winding road, an entrance of a corner, 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 28.
28. 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 29.
29. 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 30.
30. 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 Adjustments.
NO -
Go to step 31.
31. 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 Adjustments.
NO -
Go to step 32.
32. 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 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 sensor or the wheel sensors, etc.
NO -
The system is OK at this time.