32DFR114.A
4 - 5
TABLE 4-1: TROUBLESHOOTING GUIDE
Function
Symptom
Possible Cause
Remedy
Hydraulic lines are not
connected correctly
Verify that hydraulic lines to hydraulic pump, flow
control valves and hydraulic actuator are
connected correctly. Refer to
Figure 3-7
in
Chapter 3.
Ramp stows when
STOW/DEPLOY
switch is set to
DEPLOY; ramp
deploys when
STOW/DEPLOY
switch is set to
STOW; unit will only
deploy about 10
inches and will only
stow when past the
vertical mark
Leads not connected
properly on directional
valve solenoids
Verify that connector J8 (the connector with the
black and red wires) is connected to solenoid S1,
and that connector J9 (the connector with the
white and red wires) is connected to solenoid S2.
Reversed
operation
Ramp will stow when
DEPLOY switch is de-
pressed/or deploy
when STOW switch is
depressed; ramp will
operate normally
otherwise
Bus harness to ramp
interface connector is
not wired correctly
Verify that red STOW lead on STOW/DEPLOY
switch is connected to bus harness connector
P6, pin B, and the black DEPLOY lead is
connected to bus harness connector P6, pin D.
Hydraulic pump wiring
harness defective.
Check for DEPLOY VALVE INPUT signal at
directional valve solenoid S1. Repair wiring, if
required.
Deploy sensor
defective or out of
adjustment
Verify that proximity sensor is energized (LED on
sensor indicates operation) and adjusted for
correct gap. Refer to section B.6 in this chapter.
Ramp will
function in
one direction,
but not the
other
Ramp will stow, but
not deploy
Hydraulic pump
directional valve
defective
Replace hydraulic pump.
Ramp not fully stowed
Remove possible obstructions and verify that
ramp is fully stowed.
Misadjusted sensor
target or stow sensor
Verify that proximity sensor is energized (LED on
sensor indicates operation) and adjusted for
correct gap. Refer to section B.6 in this chapter.
Stow sensor defective
Replace stow sensor.
Interlocks
will not
disengage
Constant interlock
signal on ramp
interface connector
J6, pin C (orange
wire)
Electronic controller
defective
Replace controller.
Misadjusted deploy
sensor or sensor
target
Verify that proximity sensor is energized (LED on
sensor indicates operation) and adjusted for
correct gap. Refer to section B.6 in this chapter.
Deploy sensor
defective
Replace stow sensor.
Electronic controller
defective
Replace controller.
Ramp harness wiring
defective
Check for interlock signal at ramp interface
connector J6, pin C (orange lead). Repair wiring,
if required.
Interlock
does not
prevent
vehicle
departure
when ramp is
not stowed
No interlock signal on
ramp interface
connector J6, pin C
(orange wire)
Bus interlock circuit
wiring defective
Check for interlock signal from ramp via bus
harness connector pin C. Repair wiring, if
required.