Main Fuse and Grounding

Main Fuse

The main fuse has caused more than its share of problems on both the GL and the CX bikes. There are two basic types of main fuse, a fusible link and a glass cartridge style. GL's all used the fusible link style. The earlier CX bikes used the glass cartridge style.

The common failure modes are for the fuse conductor to either 1) become completely open or 2) make and break connection intermittently, often as a result of vibration while the bike is running. This happens due to age and long term exposure to vibration and is not caused by a problem someplace else in the electrical system. The fuse itself simply fails.

In the first case, the bike electrical system will be completely dead. This is generally easy to troubleshoot but it can occur at a very inconvenient time or place, possibly miles from anywhere. It's a shame that such a simple problem can leave one stranded.

The intermittent connection failure mode can be much more difficult to track down as the symptoms can vary significantly. The bike may simply run poorly, much like a carburetion problem would cause. Or it may run well and cut out periodically.

In either case, the best course of action is to correct the problem before it starts. Installation of an automotive style blade fuse is both easy and inexpensive and will eliminate the problem. This modification is described here and here.


Poor or intermittent grounding is another very common problem.

The GL500 wire harness is grounded to the frame at two locations. The first location is the main grounding point for the harness and is located under the fuel tank, in front of the ignition coils, on the left side of the bike. The wire harness ground is the green wire with the ring terminal. A solid connection from the wire terminal to the frame bare metal is essential here.

Often the nut is either loose or missing, resulting in a poor or intermittent ground connection. Alternately, the frame may have been repainted. In either case, the problem is likely due to poor maintenance by a previous owner. To correct, use a rotary wire brush or sandpaper to remove any corrosion or paint from the frame underneath the wire ring terminal. Re-install the wire ring terminal and nut, and torque the nut to spec so it won't vibrate loose later.

Symptoms of a bad ground connection at this location include a dead bike, starting only when the bike is in neutral or the clutch is pulled in and immediately dying when placed in gear, or generally weird electrical system operation.

The second wire harness ground location on the GL500 is this green wire under the rider's seat.

This ground is only used by the charging system regulator/rectifier, so its effects are limited to charging system operation. Symptoms of a poor ground here could be no charging or charging voltage out of range, either high or low. As before, a solid bare metal connection to the frame is essential here. The corrective action is basically the same.

The GL650 does not have the forward wire harness ground at the ignition coils. Instead, it has a single point ground under the rider's seat.

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Note there are actually two wires crimped in the ring terminal here instead of one as used by the GL500. By now you know the drill - ensure there is a solid bare metal connection to the frame, and that the bolt is torqued to spec so it will not vibrate loose.

There have been similar grounding problems with CX models, but I do not have specific information available. If you own a CX, it would be prudent to look for similar ground connections (i.e. a green wire with a ring terminal) and verify the connections' integrity to frame ground.

Negative Battery Cable Connection

On the GL500 and GL650, the negative battery cable is connected directly to the starter motor case. I'm not aware of any grounding issues or problems here.

It is my unconfirmed understanding that the negative battery cable on some CX models is connected directly to the frame instead, and that there have been instances of poor ground connections from here to the starter motor body. This would be something else for the CX owner to check.

Internal Starter Ground Connection

The ground connection internal to the starter is a weak point that should be addressed, particularly if starter operation appears to be sluggish or binding. This is especially important for 650 engines that require additional starting torque and are prone to kickback while starting. Detailed information can be found here and here. General starter motor service procedures are described here.

Multimeter Usage
Main Fuse and Grounding
Charging Problems
Ignition Problems
DC Voltage Testing
Resistance Tests
Wiring Fabrication and Repairs
Stray Topics

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