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Discussion Starter #1
Hi all,

Just purchased a used 2016 MDX. Everything is fine except for the ACC. It does not detect anything in front of the car. The vehicle outline that appears when ACC is engaged does not fill however much the car comes closer to the car in the front. Yet, the emergency brake system seems to work but I am not sure if it is working as intended. Can't test that!
The car does not indicate any errors, lights, or whatever. Steering assist is working fine.
Any advice?
 

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What distance do you have the ACC set at? One, two, three, or four bars? The ACC will sometimes brake late and aggressively if you have the ACC set at the one bar setting. I usually set mine to 2 or 3 bars depending on how heavy the traffic. At 2 or more bars (depending on closing speed), the ACC/CMBS will let off the throttle first to slow down before applying the brakes second. Setting the ACC to one bar in heavy traffic requires me to keep my foot over the brake pedal sometimes and acting before the CMBS kicks in too hard.

If you see the outline of a vehicle in the M.I.D. means the ACC doesn't detect a car in front of you. The filled in picture of a car mean a vehicle is detected and the ACC/CMBS is engaged adjusting the pre-set interval depending on current speed.
 

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I have not seen that before. Even at a 1 bar set distance the outline of the car should fill in solid when there is a car 4 bars' length ahead. Perhaps the radar unit is not aimed properly, like it's pointing too high and "seeing" over the cars ahead. The dealer is the only place where a qualified technician could properly re-aim the unit. You could attempt to aim it yourself but there's the risk it is done wrong and the safety systems won't work as intended.

Does your car have an aftermarket grille or any form of vinyl wrapping over the beak (where the radar sensor is located)?

Before you do anything too drastic, your best bet might just be a hard reset of the car. Disconnect the battery for a half hour or so. That typically clears codes from the ECU, maybe it could address this issue. It may not do anything at all but no harm will come from trying this.
 

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Discussion Starter #4
Thanks. Actually, I tested it in all settings. The outline does not fill in even with 4 bars and really close to the vehicle ahead.
 

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I have not seen that before. Even at a 1 bar set distance the outline of the car should fill in solid when there is a car 4 bars' length ahead. Perhaps the radar unit is not aimed properly, like it's pointing too high and "seeing" over the cars ahead. The dealer is the only place where a qualified technician could properly re-aim the unit. You could attempt to aim it yourself but there's the risk it is done wrong and the safety systems won't work as intended.

Does your car have an aftermarket grille or any form of vinyl wrapping over the beak (where the radar sensor is located)?

Before you do anything too drastic, your best bet might just be a hard reset of the car. Disconnect the battery for a half hour or so. That typically clears codes from the ECU, maybe it could address this issue. It may not do anything at all but no harm will come from trying this.
I'll try that. I think I may have to pay a visit to the delaer.
 

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I found it in the manual, page 403. Press and hold the distance button for one second. Cruise Mode Selected appears in the MID for two seconds and then the mode switches to Cruise. Repeat to switch back to ACC.
 

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Discussion Starter #8
I found it in the manual, page 403. Press and hold the distance button for one second. Cruise Mode Selected appears in the MID for two seconds and then the mode switches to Cruise. Repeat to switch back to ACC.
Thanks. I did that too. In my case, it shows ACC is on with vehicle outline icon but does not detect any vehicles
 

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Can you check the system for trouble codes or take it to something like AutoZone and have them check it? Not sure their readers are sophisticated enough to read all of the system controls for codes. If you were in my locale I'd run a diagnostic for you.
 

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Check fuse #B8 in the main under hood fuse box (20 amp). Beyond that you have to read trouble codes. There are myriad issues that can cause it not to work from things as simple as a ground wire to a failed module.
 

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Discussion Starter #11
Check fuse #B8 in the main under hood fuse box (20 amp). Beyond that you have to read trouble codes. There are myriad issues that can cause it not to work from things as simple as a ground wire to a failed module.
Thanks a lot. Is Fuse Box B, Fuse 8 is for horn/stop? Both horn and stop lights work!
 

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Sorry, I don't know which fuse it is, but horn and brake lights are tied into ACC somehow. In the trouble shooting section for Adaptive Cruise Control one of the steps is to check that fuse & it's the only fuse referenced. I scanned the section to see if I could help you out but it's all drilling down from trouble codes. I think that section is over 100 pages of checking ground wires and various power supplies and module output voltages. That's the best I can do. I'm not all that familiar with Acura because the MDX I bought in February is the 1st I've owned.
 

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Discussion Starter #13
Sorry, I don't know which fuse it is, but horn and brake lights are tied into ACC somehow. In the trouble shooting section for Adaptive Cruise Control one of the steps is to check that fuse & it's the only fuse referenced. I scanned the section to see if I could help you out but it's all drilling down from trouble codes. I think that section is over 100 pages of checking ground wires and various power supplies and module output voltages. That's the best I can do. I'm not all that familiar with Acura because the MDX I bought in February is the 1st I've owned.
Appreciate your help a lot. It seems to be a bit complicated so I am hoping I should take this to the dealer. Break and horn are working fine so the fuse must be good.
I'll update here if I learn more.
Thanks again!
 

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I have a 2018 MDX and had to replace the windshield. It took about $400 to re-calibrate the camera for ACC and lane-keeping assist system once I replace the windshield. I think the previous might not calibrate the camera properly when they replaced the windshield. I hope it gives you a clue.
 

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I have a 2018 MDX and had to replace the windshield. It took about $400 to re-calibrate the camera for ACC and lane-keeping assist system once I replace the windshield. I think the previous might not calibrate the camera properly when they replaced the windshield. I hope it gives you a clue.
I don’t think the ACC uses the windshield sensor. It uses the radar sensor in the grill.
 

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Yes, I don't see any mention of the camera in trouble shooting the ACC. It's the mini radar unit in the grill, steering angle sensor, wheel speed sensors, ABS, Brake lights, horn, brake fluid level, all sorts of circuits and sensors that need to be operable for ACC to work.
 
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