Harley Davidson Sportster: Why is My ABS Light On?
In 2014 the Harley Davidson Sportster received some great changes, and the most important one is the ABS (Anti-Lock Brake System). No matter if the road is clean and the weather is perfect, riding with ABS offers an added level of security that many riders appreciate. It is offered as an option, but hey, it is a first for the Sportster lineup.
This article applies to the Harley Davidson Sportster (2014-2015).
The Harley Sportster ABS is a non-linked system. A non-linked system allows independent control of the front as well as rear brake, and uses the standard brake master cylinders and calipers. There are only a few other pieces of the ABS and they are:
- ABS module
- Wheel speed sensors
- Magnetic equipped wheel bearings
- Brake lines that connect them
The wheel speed sensors read the wheel bearings and sends signals back to the ABS module, which continuously monitors wheel speed for too great of a difference between the front and back wheels. Also, If one or both wheels slow down too quickly (indicating that they're close to locking), the ABS module instantly responds, rapidly opening and closing valves to modulate the brake pressure. The system is pumping the brakes for you, faster than you can, several times per second. This pulsing sensation in the brake pedal and/or hand lever and clicking noise from the module are normal.
The Harley system performs a check when you first turn the ignition key. The light will flash, and continue flashing until the system completes a self-diagnostic check and the bike reaches a speed of approximately three miles per hour. If everything checks out, the light goes dark. If the warning light stops flashing and stays on, the ABS system has detected something wrong and has deactivated. With the light lit, you still have the full function of the bikes, they just operate like a non-ABS bike.
Material Needed
- Only two good eyes and a lot of attention
Step 1 – Check your tires and wheels
ABS motorcycles must always use the correct sized tires and wheels; if they are different from what Harley recommends, it can confuse the ABS system. ABS monitors the rotational speed of the wheels through individual wheel speed sensors front and rear. Changing to different diameter wheels or even different sized tires can alter the rotational speed, as can a tire that is really low on air. The system needs to know the tire diameter to know if the front and back tires are rolling at the same speed, or if one is about to lock up. Unfortunately, the only solution to this one appears to be changing back to the correct sizes, though you can try resetting the module to see if it helps.
Figure 2. 2014 Harley Davidson Sportster tire sizes. 
Figure 3. 2015 Harley Davidson Sportster tire sizes.
Step 2 – Reset the ABS module
It is possible for the ABS module to read an error that confuses it. The easiest way to reset the computer and module is to disconnect the battery. First try pulling the main fuse, which is like the other fuses only much bigger, and this doesn't require tools. Disconnect and wait at least a minute, then reconnect. Removing the battery cables is also simple and takes just a few minutes. If the fuse doesn't work, try the battery, both are easy enough to do. Start your engine and do a little trip around your home to see if the ABS light goes out. If not, see the next step.
Step 3 – Check the ABS sensor wire
Usually, the ABS sensor wire is held in 2 or 3 points in order to avoid excessive movements. It can come loose, get pinched or break. On top of that, the repeated oscillation of the free parts of the ABS sensor cable can lead to breaking of wire isolation and even to the breaking of the wire itself. The wear can be easily seen and (if it's there) that means only one thing: replacement of the ABS sensor wire. Also, because the wire can't be detached from the sensor, the next step is to replace the whole ABS sensor.
Step 4 – Replace the ABS sensor
Replacing the sensor is an easy enough operation, as it just goes on the axle in place of a wheel spacer. The sensor reads a magnet built into the front wheel bearing, and magnets usually don't go bad. But if a previous owner has changed the wheels, or replaced the bearings, it is possible they did not use the correct ABS specific bearing.
In the above image:
- On the left side: the larger wired piece is the sensor that reads the encoded magnet (the thin brown ring, which is exposed for display) hidden away in the sealed bearing residing in the wheel hub.
- On the right side: the ABS sensor as an assembled unit.
Related Sites
- Harley Davidson ABS Explained - Harley-Riders-Guide.com
- Harley Davidson Anti-Lock Braking System - Harley-Davidson.com
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2014 Harley Sportsters Get New Brakes and ABS - Motorcycle-USA.com
