ACC Troubleshooting
  1. Check for continuity between the ACC unit 20P connector terminals No. 11 and No. 12 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 21 .
NO -
Repair an open in the wire or poor ground (G502). ■
  1. Check the vehicle's history for front end collision repairs.
Have the vehicle been repaired?
YES -
Go to Step 8 .
NO -
Go to Step 9 .
  1. 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. ■
NO -
Reinstall the part correctly, or if damaged, replace the part, then aim the millimeter wave radar. ■
  1. Check the wheel alignment.
Is the wheel alignment OK?
YES -
Go to Step 10 .
NO -
Adjust the wheel alignment. ■
  1. Find out when the system has misdetections.
Do they occur within 20 minutes or less?
YES -
Go to Step 11 .
NO -
Explain to the customer that system misdetections are sometimes caused by the environment (weather, road conditions, driving conditions, etc.).■
  1. 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 customer that system misdetections are sometimes caused by the vehicle types.■
NO -
Go to Step 12 .
  1. Check for dirt, dust, or snow on the surface of the millimeter wave radar 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.■
  1. Check if there was a heavy load in the trunk or if the vehicle was used for towing.
Was there a heavy load in the trunk or was the vehicle towing?
YES -
Remove the heavy load from the trunk and/or advice the customer that this problem may occur temporarily when hauling loads or towing.■
NO -
Go to Step 14 .
  1. Measure the front and rear vehicle ride height.
Is the vehicle ride height equal?
YES -
Go to Step 15 .
NO -
Adjust the wheel alignment. ■
  1. 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 customer that the system sometimes cannot detect under certain road conditions.■
NO -
Go to Step 16 .
  1. 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 customer that the system sometimes cannot detect under poor weather conditions.■
NO -
Go to Step 17 .
  1. 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 4 m (13 ft).
Does it occur only under certain driving conditions?
YES -
Explain to the customer that the system sometimes cannot detect under certain driving conditions.■
NO -
Go to Step 18 .
  1. 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 .
  1. 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 .
  1. 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 customer that intermittent failures are sometimes caused by environmental conditions.
Is the vehicle unstable (Compare to a known-good, like vehicle.)?
YES -
Check the other components such as the yaw rate-lateral acceleration sensor or wheel speed sensors, etc.■
NO -
The system is OK at this time.■
  1. 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. There is no DTC for dirty conditions.■
  1. 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 .
  1. 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. ■
NO -
Reinstall the part correctly, or if damaged, replace the part, then aim the millimeter wave radar. ■
  1. Check if there was a heavy load in the trunk or if the vehicle was used for towing.
Was there a heavy load in the trunk or was the vehicle towing?
YES -
Remove the heavy load from the trunk and/or advise the customer that this problem may occur temporarily when hauling loads or towing.■
NO -
Go to Step 25 .
  1. Measure the front and rear vehicle ride height.
Is the vehicle ride height equal?
YES -
Go to Step 26 .
NO -
Adjust the wheel alignment. ■
  1. 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 customer that the system sometimes cannot detect certain vehicle types.■
NO -
Go to Step 27 .
  1. 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 customer that the system sometimes cannot detect under certain road conditions.■
NO -
Go to Step 28 .
  1. 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 customer that the system sometimes cannot detect under poor weather conditions.■
NO -
Go to Step 29 .
  1. 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 4 m (13 ft).
Does it occur only under certain driving conditions?
YES -
Explain to the customer that the system sometimes cannot detect under certain driving conditions.■
NO -
Go to Step 30 .
  1. 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 31 .
  1. 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 32 .
  1. 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-lateral acceleration sensor or wheel speed sensors, etc.■
NO -
The system is OK at this time.■