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Harley Davidson Sportster: Fuse Box Information

The fuse box contains the protection your Sportster's electrical system needs to prevent shorts from becoming fires. Fuses purposely serve as the weak link in the circuit, but sometime just blow randomly. Always start at the fuse box when your Sportster experiences an electrical problem.

By Weston Chadwick - February 5, 2016

This article applies to the Harley Davidson Sportster (2000-2015).

Fuses, relays, and circuits breakers: they're all circuit protection devices that can be found inside your Sportster's fuse box, depending on its year. Harley Davidson designs an electrical circuit to withstand only a certain amount of amperage. When the amperage exceeds design limits (usually during a short), excessive heat is created and breaks or opens the circuit protection device. Relays are used to control a circuit that uses high current with a low current circuit. This reduces wiring size and lessens the chance for a damaging short to occur at the switch.

Component Breakdown

Fuse

Fuses are used to protect electrical circuits from over current. When a wire finds a path to ground that's bypassing the device it's powering, a shorter circuit is made. This generates heat and melts the metal strip inside the fuse. Without the right fuse (amp rating on top of the fuse), a fire can occur. Blown fuses are generally easy to spot because the fuse window (middle section) will appear dark and discolored. Fuses are easily removed from the fuse box with a pair of pliers. You can check to see if the fuse is blown without removal by using a digital volt ohm meter. Connect both probes to each side of the fuse. If continuity is present, the fuse is good. A blown fuse does not necessarily mean there's a short present. Sometimes fuses wear or break because of vibration. Always try replacing the fuse before performing any diagnostic work.

  • Good fuse vs. bad fuse
    Figure 1. Good fuse vs. bad fuse.
  • Testing a fuse with a multi-meter
    Figure 2. Testing a fuse with a multimeter.

Relay

Relays are another type of circuit protection device. They use an internal magnetic switch to allow a smaller current to control a larger one. Looking at Figure 3, you can see connections 85 and 86 complete the circuit from the switch ground to the switch. When you hit the switch, low current flows through the relay coil (85-86), which uses a magnet to make a connection between 87 and 30, completing the circuit. There are several test to completely determine whether a relay works or not. Start by applying power to the relay with the relay still installed; you should hear and feel a click as you hit the switch. If no click is heard or felt, the relay is probably bad. If the relay clicks but the circuit still doesn't work, remove the relay from the fuse box. For a step-by-step explanation of how to diagnose and test relays check out this video.

A circuit consisting of a one pole relay
Figure 3. A circuit consisting of a one pole relay.

Data Link Connector

The data link connector is the dealers gateway into the Sportster computer system. This connector pairs with a scan tool to read trouble codes, view live data, and program modules. Many aftermarket scan tools and performance tuners use this connector as well. Simply plug them into the connector and you'll have access to most, if not all, the information your local Harley Davidson dealer has.

The fuse box from a 2005 Sportster
Figure 4. The fuse box from a 2005 Sportster.

Common Questions

How do I gain access to the fuse box?

You'll need to remove the triangular side cover on the left side of motorcycle, below the seat. Gently pull on the upper portion of the cover away from the frame. You'll feel the two clips at the top of the cover disengage. To re-install, place the grommet on the bottom of the cover into the frame and snap the two clips together at the top.

The fuse box cover
Figure 5. The fuse box cover.

Where can I find a fuse box diagram?

There may be a diagram on the inside of your fuse box cover. If not, you can find one in your owner's manual. A copy of your manual can be downloaded directly from the Harley Davidson website. You'll find a diagram in the figure below as well.

The fuse box diagram from a 2009 Sportster
Figure 6. The fuse box diagram from a 2009 Sportster.

How many times has the fuse box location/design been changed?

On earlier model Sportsters (1990's), you'll find the fuses under the seat and behind the battery. There is a triangular cover that protects the fuses. Pull it up and off the fuse box to access the fuses. 1980's model Sportsters instead use circuit breakers in the same location. A circuit breaker opens when a short is created and automatically closes once the current flow in the circuit lowers to a normal level. 2000's + model Sportsters have their fuse box located behind the cover pictured in Figure 4.

The circuit breakers from a 1981 Sportster
Figure 7. The circuit breakers from a 1981 Sportster.

Common Issues

Corrosion Inside the Fuse Box

On newer model Sportsters with the triangular fuse box side cover, water has been known to leak past the cover and corrode the connections. Some symptoms of water corrosion include hard starting, a drained battery, and relays/switches turning on with the ignition off. To correct this problem, di-electric grease can be applied around the fuses, relays, and connections to help form a seal. It will still be necessary to periodically clean these areas. A thin strip of rubber, like the seal used on car doors, can be wrapped around the covers edge as well.

Corrosion found inside the fuse box
Figure 8. Corrosion found inside the fuse box.

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