Handle And Carburetor Heating System; 14.3.1 Troubleshooting - Stihl MS 661 Manual

14.3 Handle and Carburetor
Heating System

14.3.1 Troubleshooting

The entire handle heating system is
maintenance-free and subject to
practically no wear. Faults in the
generator, heating elements and
wiring are generally caused by
mechanical damage.
There are two reasons for failures in
the heating system:
1. A break in the circuit
due to a faulty wire or
component.
2. A short circuit resulting from
damage to the insulation.
– Remove the handle molding and
lockout lever, b 11.2
: Pull one of the connectors out of
the guide and push the insulating
tube (1) in the direction of the
wiring harness.
: Separate the pin and socket
connector (1).
MS 661, MS 661 C-M
: Set the heater switch (1) to "F".
– Set the ohmmeter to "Ω".
– Set Master Control lever to
1
"STOP" and hold it there.
: Clip the test leads to the
connecting wire and the rear
handle heating element wire.
Carburetor heating
– Take out the screw and remove
the thermostatic switch wire, then
refit the screw and tighten it down
firmly, b 13.4
All electrical components of the
handle heating system are
connected in series with the
ohmmeter.
1
If the system is in order, the
ohmmeter will indicate a value of
about 10 Ω in measuring range "Ω".
If no reading is obtained, there is a
break in the circuit.
If the ohmmeter shows a very low
value, there is a short circuit in one
of the components.
1
In either case it is necessary to
check each component separately.
The thermostatic switch remains
disconnected.
– Use handle heating and
generator troubleshooting chart
to check the system, b 14.7.1
– Check resistance on handlebar,
b 14.6
– Check resistance on rear handle,
b 14.5
– After completing the test,
reconnect the wires and push the
insulating tube over the pin and
socket connector.
– Reassemble in the reverse
sequence.
121