TM 9-2320-273-20
2-63. BRAKE SWITCHES AND INDICATORS.
1. STOP LAMP SWITCH. Normally open air actuated switch, which closes when brakes are
actuated. The switch receives 12-volt battery power from circuit breaker CB-1 and supplies
this power through the operation switch in NORMAL position, turn signal control to the
tractor tail stop lamps. Also, with switch closed, 12-volt battery power is routed through
the operation switch to the 12-volt trailer receptacle.
2. PARK BRAKE INDICATOR. Illuminates when the park brakes are applied. Indicator re-
ceives 12-volt battery power through engine run switch in ON position, circuit breaker
CB-6, and actuated parking brake switch.
3. OPERATION LAMP SWITCH. Two-position switch for NORMAL and BLACKOUT modes
of operation. With the switch set to NORMAL, 12-volt battery power is received from
closed stop lamp switch, and circuit breaker CB-1. This 12-volt power is supplied through
the turn signal control to the tractor tail stop lamp. 12-volt power is also supplied to the
12-volt trailer receptacle.
4. PARK BRAKE SWITCH. Normally open, air actuated switch on parking brake (para 2-62).
Closes to energize park brake indicator when parking brakes are actuated.
5. ClRCUIT BREAKER (CB-6). Protects electrical components of parking brake circuit by
opening when load exceeds 20 amps. Automatically recycles until overload is removed.
6. ClRCUIT BREAKER (CB-1), Protects electrical components of stop lamp circuit by open-
ing when load exceeds 20 amps. Automatically recycles until overload is removed.
7. STOP TAIL LAMPS. Unit contains two bulbs, a single-filament bulb for backup, and a
two-filament bulb for tail, turn signal, and stop lamps. The stop lamps receive 12-volt
power through circuit breaker CB-1, closed stop lamp switch, closed contacts of operation
switch, and the turn signal control.
8. ClRCUIT BREAKER (CB-6). Protects electrical components of parking brake circuit by
opening when load exceeds 20 amps. Automatically recycles until overload is removed.
9. 12-VOLT TRAILER RECEPTACLE. When the stop lamp switch is closed and the operation
switch is in NORMAL, 12-volt battery power is supplied to the tractor mounted receptacle
for trailer stop lamps.
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