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 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 20P connector from the ACC unit.
3. Turn the ignition switch ON (II).
4. Measure the voltage between the ACC unit 20P connector No. 2 terminal 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 under-dash fuse/relay box and the ACC unit. If the wire is OK, replace the under-dash fuse/relay box.
5. Turn the ignition switch OFF.
6. Check for continuity between the ACC unit 20P connector No. 11 and No. 12 terminals and body ground 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 22.
NO - Repair an open in the wire or poor ground (G401).
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 unit 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 unit.
NO - Reinstall the part correctly, or if damaged, replace the part, then aim the millimeter wave radar unit.
9. Check the wheel alignment.
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 misdetection occurs only with certain types of vehicles.
Does it occur only with certain types of vehicles such as a truck, motorcycle, or special vehicle?
YES - Explain to the client that system misdetections are sometimes caused by the vehicle types.
NO - Go to step 12.
12. Check for dirt, dust, or snow on the surface of the millimeter wave radar unit and the emblem.
Are the radar and emblem OK?
YES - Go to step 13.
NO - Clean the radar and the emblem. There is no DTC for dirty conditions.
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 customer 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 - Adjust the wheel alignment.
15. 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 16.
16. 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 17.
17. Find out if the detection problem occurs only under poor weather conditions such as a 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 unit 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 unit 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 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 unit and the emblem.
Are the radar unit and the emblem OK?
YES - Go to step 23.
NO - Clean the radar unit and the emblem. There is no DTC for dirty conditions.
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 unit 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 unit.
NO - Reinstall the part correctly, or if damaged, replace the part, then aim the millimeter wave radar unit.
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. Advice 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.
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, 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 a 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 unit 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 unit 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?
YES - Check the other components such as the yaw rate sensor or wheel sensors, etc.
NO - The system is OK at this time.