TRUCK SERVICE MANUAL
dependently on a straight truck to be sure both are
functioning. Disconnect one switch.
2. Apply brake valve and note that with first
downward movement of pedal or treadle that the
stop lights go on immediately.
3. Release brake valve and note that stop lights of
4. If lights fail to go on use a test light at stop light
connections. Test both terminals to determine if
an electrical supply is available at switch; then
"bypass" the switch with test light or jumper wire.
Lights should go on. If not, a failure in the
electrical circuit is the problem. However, if
lights work, replace stop light switch.
Automatic Reservoir Drain Valve
With brakes applied there should be no air
leakage at stop light switch.
With no air pressure in air system, the inlet and
exhaust valves are closed (Fig. 9).
1. Disconnect electrical connections. Be sure to keep
electrical connections from frame, etc. Tape
2. Remove switch from air fitting.
1. Install stop light switch in air fitting.
2. Install electrical connections.
After stop light switch is reinstalled, perform
AUTOMATIC RESERVOIR DRAIN VALVE
The DV2 Automatic Reservoir Drain Valve ejects
When charging the air system, a slight pressure
is connected. It operates automatically and requires no
to collect in sump (Fig. 10).
manual assistance or control lines from other sources.
The automatic reservoir drain valve has a die cast
aluminum body and cover and is normally mounted
either in the bottom of the reservoir using the top port of
the drain valve or in the end of an end drain reservoir
using the side port of the valve.
For vehicles operating in subfreezing
temperatures, the valve is also available with a heater
and thermostat cast into the cover.