TM 5-3805-254-20-1
ORGANIZATIONAL TROUBLESHOOTING - CONTINUED
MALFUNCTION
TEST OR INSPECTION
CORRECTIVE ACTION
17. ENGINE COMPRESSION BRAKE DOES NOT WORK - CONTINUED.
WARNING
Although KEY SWITCH must be on and battery ground cable connected to test electrical circuit
voltage, turn off KEY SWITCH and disconnect battery ground cable before doing resistance tests
or replacing parts. This will keep you from getting shocked and prevent damage to parts and
equipment.
Step 2.
Set multimeter to 20 vdc scale. Connect red test lead to output terminal (1) on engine compression brake
circuit breaker (2) and black test lead to ground. Rotate KEY SWITCH (3) clockwise to on position and
check for 11 to 13 vdc on multimeter. Rotate KEY SWITCH (3) counterclockwise to off position.
Disconnect test leads.
a.
If multimeter does not read 11 to 13 vdc, replace engine compression brake circuit breaker (2) (page 2-748).
b.
If multimeter reads 11 to 13 vdc, go to step 4.
Step 3.
Set multimeter to 20 vdc scale. Connect red test lead to input terminal (4) on backup light circuit breaker (5)
and black test lead to ground. Rotate KEY SWITCH (3) clockwise to on position and check for 11 to 13 vdc
on multimeter. Rotate KEY SWITCH (3) counterclockwise to off position. Disconnect test leads.
a.
If multimeter does not read 11 to 13 vdc, go to step 5.
b.
If multimeter reads 11 to 13 vdc, 14 wire (6) must be replaced. Notify Direct Support Maintenance.
Step 4.
Open lower center instrument panel (page 2-424). Set multimeter to 20 vdc scale. Connect red test lead to
input terminal (7) on COMPR BRK switch (8) and black test lead to ground. ROTATE KEY SWITCH (3)
clockwise to on position and check for 11 to 13 vdc on multimeter. Rotate KEY SWITCH (3)
counterclockwise to off position. Disconnect test leads.
a.
If multimeter does not read 11 to 13 vdc, 24 wire (9) must be replaced. Notify Direct Support Maintenance.
b.
If multimeter reads 11 to 13 vdc, go to step 6.
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