Electric starting systems are now found on almost all
powersports vehicles. All electric starting systems have two separate circuits:
one for low-current, and one for high-current. Both circuits are connected to
the battery.
When the starter motor is activated, it requires a large
amount of current to turn the engine over. The high-current circuit carries
this current to the starter motor from the battery. This circuit is easily
identifiable as it must use a heavier gauge wire to handle the high-current.
The 6- to 8-gauge wires that connect the positive battery terminal to the
starter relay and the starter relay to the
the low-current circuit controls the high-current circuit.
starter motor make up the high-current circuit, along with
the high-current contacts in the starter relay.
The high-current circuit is controlled by the low-current
circuit. The low-current circuit uses smaller wires, usually 16- to 12-gauge.
The central components of this circuit are the battery, main/ignition switch,
engine start switch, fuse and coil winding inside of the starter relay.
When the engine start switch is activated, the low-current
circuit is completed and an electromagnetic field is created inside the starter
relay. This electromagnetic field closes the high-current contacts and
completes the high-current circuit. The high-current flows through the
heavy-gauge wire to power the starter motor. When the engine start switch is
released, the low-current circuit is opened, and as a result, the high-current
contacts open and the high-current flow to the starter motor is stopped.
account for the entire circuit when troubleshooting.
Most starting circuits are designed to keep the starter
motor from turning under unwanted conditions. This may involve brake, clutch,
side-stand or neutral switches that will not allow the low-current circuit to
complete unless optimal starting conditions exist. If the starting system isn’t
functioning correctly, troubleshoot the whole circuit and not just the main
components.
When inspecting an electric starting system, be sure to
start with a battery that is fully charged. Locate the starter relay. Attempt
to start the engine and listen to the starter relay. The starter relay should
click. If the relay clicks, the low-current circuit of the starting system is
complete.
listen for the starter relay to click.
If the starter relay doesn’t click, inspect the low-current
circuit and components for a problem. Almost all starter relays can be tested
in the same manner.
Disconnect the high-current lead from the positive terminal
of the battery and unplug the low-current connector from the starter relay.
Jump 12 volts directly to the low-current input terminals of the starter relay.
Check for continuity between the high-current terminals.
When the jump is completed, there should be continuity
between the high-current terminals. When the jump is open, there should not be
continuity between the high-current terminals. Replace the starter relay if it
fails this test.
test for continuity between the high-current terminals of the starter relay.
If the starter relay is clicking but the starter motor is
not turning, there is a problem with the high-current circuit. Check for a poor
connection in the heavy-gauge wires between the battery and starter relay, and
the starter relay and the starter motor. The problem could lie with the starter
motor if the high-current wires and connections check out.
Check if the starter motor will turn when powered.
To test the starter motor, jump 12 volts directly to it and
see if it turns. Be sure to prepare the vehicle for the starter motor turning,
as the low-current circuit safety precautions will be bypassed in this test. If
the starter motor doesn’t turn, it is either faulty or locked up by a
mechanical engine problem.
original page from:
https://www.motorcyclepowersportsnews.com/starter-system-troubleshooting
