Diag Code C1021
Thread Starter
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Cruiser
Joined: Jan 2018
Posts: 111
Likes: 77
From: Southwest Michigan
Diag Code C1021
Good Morning All,
Changed the front tire. ABS ligth stays on and I have a C1021 Front Wheel Speed Sensor (WSS) always reading zero. This is a list of what I have done.
1. Confirmed the wheel was installed with the ABS bearing in the correct location
2. Confirmed the ABS Sensor is installed "clocked" in the correct position
3. Chase wire to plug and confirmed it is plugged in tight.
4. Cleaned bearing surface and sensor surface of grease and debriss.
5. Cleared all codes and it still comes back
6. Tried to activate ABS system. (locked up tire)
7. Flushed front and rear brake fluid.
Can the sensor be tested with a multimeter?
Please respond even if you think I have already covered it. Any sugestion will be greatly appreciated.
Thank you for your help.
Changed the front tire. ABS ligth stays on and I have a C1021 Front Wheel Speed Sensor (WSS) always reading zero. This is a list of what I have done.
1. Confirmed the wheel was installed with the ABS bearing in the correct location
2. Confirmed the ABS Sensor is installed "clocked" in the correct position
3. Chase wire to plug and confirmed it is plugged in tight.
4. Cleaned bearing surface and sensor surface of grease and debriss.
5. Cleared all codes and it still comes back
6. Tried to activate ABS system. (locked up tire)
7. Flushed front and rear brake fluid.
Can the sensor be tested with a multimeter?
Please respond even if you think I have already covered it. Any sugestion will be greatly appreciated.
Thank you for your help.
Last edited by BigFuji; Apr 13, 2026 at 08:17 AM.
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Joined: Apr 2015
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Assuming everything you say is true, there is no damage to the bearing and the ABS sensor or wiring, you either have a faulty ABS bearing and/or a faulty ABS sensor. I dont know what else it could be other than a faulty ABS module, but that would seem unlikely.
Did you clear the code through the bike or through a tuner?
Stock wheel and tire?
Original OEM ABS bearing?
Did you clear the code through the bike or through a tuner?
Stock wheel and tire?
Original OEM ABS bearing?
Thread Starter
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Cruiser
Joined: Jan 2018
Posts: 111
Likes: 77
From: Southwest Michigan
OEM Wheel.
OEM Bearing.
Cleared the code with the handlebar controls.
I have found two way to check the sensor.
Onhms Test
If the sensor is good it will show 900-1500 ohms
If it is infinite or zero it is a bad sensor
AC Test
When you spin the wheel you should get 0.1 to 0.5v AC
If it is zero, bad sensor
I will perform these tests Tuesday. No time to get to it today.
Thank you for your responce.
OEM Bearing.
Cleared the code with the handlebar controls.
I have found two way to check the sensor.
Onhms Test
If the sensor is good it will show 900-1500 ohms
If it is infinite or zero it is a bad sensor
AC Test
When you spin the wheel you should get 0.1 to 0.5v AC
If it is zero, bad sensor
I will perform these tests Tuesday. No time to get to it today.
Thank you for your responce.
Thread Starter
|
Cruiser
Joined: Jan 2018
Posts: 111
Likes: 77
From: Southwest Michigan
I went home for lunch and tested my sensor.
Ohms Test Result: 746
Bad Sensor, no soup for you!
Side Note:
An ABS Bearing and a Non-ABS are physically the same size bearing.
The only differnce is the ABS Bearing incorporates a magnetic ring that needs to be installed outward on the appropiate side. The bearing will be marked for this reason.
So if you have a non-abs bike there is no need to change to non-abs bearings.
Ohms Test Result: 746
Bad Sensor, no soup for you!
Side Note:
An ABS Bearing and a Non-ABS are physically the same size bearing.
The only differnce is the ABS Bearing incorporates a magnetic ring that needs to be installed outward on the appropiate side. The bearing will be marked for this reason.
So if you have a non-abs bike there is no need to change to non-abs bearings.
Last edited by BigFuji; Apr 13, 2026 at 02:28 PM.
Seasoned HDF Member
Joined: Apr 2015
Posts: 10,000
Likes: 5,266
Im curious where you found the resistance numbers for Harley wheel speed sensors.
If you can get your DMM leads on the WSS wire terminals and, at the same time, spin the wheel, you should get an AC voltage reading. How fast you spin the wheel will determine what voltage you get, which wont be much, but it should show some voltage.
If you can get your DMM leads on the WSS wire terminals and, at the same time, spin the wheel, you should get an AC voltage reading. How fast you spin the wheel will determine what voltage you get, which wont be much, but it should show some voltage.
Last edited by GalvTexGuy; Apr 13, 2026 at 03:33 PM.
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Joined: Sep 2008
Posts: 14,056
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From: San Diego, CA
Side Note:
An ABS Bearing and a Non-ABS are physically the same size bearing.
The only differnce is the ABS Bearing incorporates a magnetic ring that needs to be installed outward on the appropiate side. The bearing will be marked for this reason.
So if you have a non-abs bike there is no need to change to non-abs bearings.
Unless it changed sometime during the later M8 years, since about 2008, the ABS bearings were about 3mm thicker than the non-ABS bearings.
IIRC they were:
ABS = 25mm x 52mm x 18mm
Non-ABS = 25mm x 52mm x 15mm
Note: I was being brave and pulled those measurements out of my head. I was being to lazy to double check my memory. If I remembered wrong, I will surely be corrected...
Thread Starter
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Cruiser
Joined: Jan 2018
Posts: 111
Likes: 77
From: Southwest Michigan
It is 2017 lLimited
i got a zero AC reading when I spin the wheel.
i searched the internet for the sensor data.
i got a zero AC reading when I spin the wheel.
i searched the internet for the sensor data.
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Seasoned HDF Member
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I have no idea what your mechanical and electrical troubleshooting aptitude is, so if you take my post as an insult, it wasnt meant to be.
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From: memphis
was the abs bearing removed and reinstalled at any time. if the tire and rim was removed for a tire replacement there would be no issues reinstalling the wheel the same way it was removed.
Thread Starter
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Cruiser
Joined: Jan 2018
Posts: 111
Likes: 77
From: Southwest Michigan
That is a good observation. So I went to McDaniels Harley Davidson in South Bend Indiana and asked the parts counter that very question. Good range for the ohms reading is 1000-1500. Anything less than that is a bad sensor. The AC reading would be very small, .01 to .05v
The ABS bearing has not been removed. I marked the rotors with blue tape and a sharpie. I noted ABS sensor side and rotation direction arrows. If there is one thing I have learned in 59 years on this planet is you check and double check. My friends call me funny names for thses traits but they all admit, when it is done it is done correctly.
The sensor has been ordered and I will update if anything else comes up. Than you so much for the replies.
The ABS bearing has not been removed. I marked the rotors with blue tape and a sharpie. I noted ABS sensor side and rotation direction arrows. If there is one thing I have learned in 59 years on this planet is you check and double check. My friends call me funny names for thses traits but they all admit, when it is done it is done correctly.
The sensor has been ordered and I will update if anything else comes up. Than you so much for the replies.