TRANSMISSION SHIFT LEVER POSITION
If voltage readings are not correct, gear
APC 100 CONTROL BOX DIAGNOSTICS
selector or cab harness is faulty.
Correct as necessary and check vehicle
Remove blackout cover from APC 100 control
box to expose the three diagnostic LEDs.
With transmission selector lever in N and
ignition switch positioned to 1 (run), observe the
continuity between any two circuits and no continuity
three diagnostic LEDs and the TRANSmission RPM/
between any circuit and ground.
PRESSure indicator (LED) on dash panel. All four
should light for 2 seconds, then the TRANSmission
If continuity is as stated, proceed to step
RPM/PRESSure indicator should begin to blink
slowly and the red diagnostic LED should turn off.
The yellow and green LEDs should remain on.
If continuity is not as stated, check the
harnesses and circuits in main junction
If no LEDs light, check for 24 vDC power
box (exterior, back side of cab) for
and ground at the rectangular connector
cause. Correct any fault(s) and check
for the APC 100 control box harness.
If no power is indicated, check
harness circuit #718.
should be available at sockets
17, 18, and 25 of APC relay box
of current to operate, even a small strand
harness. Correct any fault(s) and
of wire may cause undesirable continuity
If no ground is indicated, check
10. Remove cover from fuse and relay box and
harness circuit #51.
check for loose connections, blown fuses, and bad
should be available at socket 11
relays. Correct any fault(s) and check vehicle
of APC 100 relay box harness.
Correct any fault(s) and recheck
If power and ground are present,
The cab harness needs to be
check input fuse under top cover
of APC 100 control box, refer to
reactivated for the relays to be in their
Figure 2-3-15. If blown, replace
manual mode position.
only with a 5 x 20 mm very fast
acting (FF) 315 mA fuse.