THEORY OF OPERATION - (CONTINUED)
TRANSMISSION CIRCUIT RELAY (CRT)
When energized power is applied from the CRT relay contacts (FO-1, line19), to the park position brake release
and engages circuits, through the transmission shifter assembly (park position) to energize the park relay (CRS).
ACCESSORY RELAY (CRA)
When energized power is applied from the CRA relay contacts (FO-1, line 24), to the glow plug circuit, park position
motor circuit, fuel heater circuit, horn circuit and all vehicle lighting circuits.
GLOW PLUG RELAY (CRGP)
This relay is energized when the glow plug switch (SW7) is placed to the on position. When energized a set of
contacts is closed (FO-1, line 3) which allows power to the glow plugs during cold weather starting.
TIME DELAY RELAY (TRD)
This relay provides a power removal delay of one second to the transmission shifter assembly; this allows the
transmission to be fully disengaged after placing the transmission shifter to the park position.
PARK POSITION (TRANSMISSION) BRAKE RELEASE RELAY (CRR)
This relay is energized when the transmission shifter is moved to any position other than park, which allows the
park position motor (FO-1, line 31) to disengage the caliper located on the transmission output shaft disc. Power to
this relay is controlled by the limit switch LS-PR (FO-1, line 35).
PARK POSITION (TRANSMISSION) BRAKE ENGAGE RELAY (CRP)
This relay is energized when the transmission shifter is moved to the park position, which allows the park position
motor (FO-1, line 31) to engage the caliper located on the transmission output shaft disc. Power to this relay is
controlled by the limit switch LS-PE (FO-1, line 37).
PARK RELAY (CRS)
This relay is energized with the transmission shifter in the park position, which closes a set of contacts (FO-1, Iine
9) which will allow the engine starter to be engaged. The hand brake must also be engaged.
INTERLOCK RELAY (CRI)
This relay works in conjunction with the park position brake limit switches LS-PR and LS-PE to engage and
disengage the park position brake caliper located on the transmission output shaft disc. The park position motor
(FO-1, line 31) moves a caliper actuator rod up and down, engaging and disengaging the brake caliper as the
transmission gear shifter is shifted from park to any gear selection and back to park.
FUEL HEATER CIRCUIT
Power is applied through a 25 amp fuse (10FU) to a fuel heater coil located inside the fuel water separator
assembly. This heater aids with engine starting.
Power is applied through a 5 amp fuse (11FU) to a horn located under the front of the vehicle. A push button horn
switch located on the steering wheel provides ground to energize the horn when pressed.