MWO-9-2320-272-35-1
MODIFICATION OF 5-TON M939, M939A1, M939A2 SERIES FAMILY OF VEHICLES (FOV)
M939 BRAKE STABILIZATION PROGRAM (RETROFIT OF ANTI-LOCK BRAKE SYSTEM (ABS) FOR M939 FOV); MODIFICATION WORK ORDER
JANUARY 2007
CHANGE 1
MWO-9-2320-272-35-1 - Page 25 of 109
MWO 9-2320-272-35-1
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(5)
Listen for air dryer to purge at compressor cut-out.
(6)
Shut engine down (TM 9-2320-272-10).
(7)
Listen for leaks at reservoirs and throughout all air system plumbing. Soap solution is
recommended to check integrity of fittings. Tighten or repair any leaks.
d. Parking Brake Operational Test
(1)
Release parking brakes (TM 9-2320-272-10).
(2)
Visually check spring brake chambers to ensure parking brake spring is being compressed
inside brake chamber when parking brakes are released (remove spring brake dust cover to
allow visual access). One person needs to watch brake chamber while a second person releases
parking brake.
(3)
Reapply parking brakes (TM 9-2320-272-10). Verify exhausting air is heard at vent stack.
e. Delivery Air and ABS Test
(1)
Release parking brakes (TM 9-2320-272-10).
(2)
Apply full brake pressure and listen for delivery air leaks (monitor dashboard pressure gauges
– pressure drop should not exceed 5 psi per minute).
(3)
With full brake pressure still applied, turn battery switch to ON position and starter switch to
RUN position.
(4)
Listen for two ABS relay valves to Blow-Down (a quick exhaust of control air through valve
exhaust port) front valve should blow-down first, followed by rear valve.
(5)
Verify ABS indicator lamp in dashboard turns ON for approximately two seconds, then turns
OFF during valve blow-down cycle.
(6)
Verify display on Haldex Info-Centre briefly shown C1 then changes to a steady 07 (the 07
indicates system is OK and stationary). If lamp does not illuminate, remains on or a code other
than 07 appears, refer to Diagnostic and Troubleshooting (step j).
f.
ABS Sensor Checks
(1)
Turn battery switch to ON position and starter switch to RUN.
NOTE
NOTE
The Haldex Info-Centre may also “lock” sensor check
display by pressing on right hand button on face of Haldex
Info-Centre. The display will show “WHL” to left. You may
then spin wheel and display will show “S2B” to indicate
this sensor is sensing wheel motion. This feature allows
one person to perform this test unassisted.
(2)
Verify passenger side sensor is properly connected and positioned by rotating passenger side
hub and wheel at a rate of approximately 1 revolution every 2 seconds. The Haldex Info-Centre
should display “S2B” while wheel is turning.
NOTE
NOTE
The Haldex Info-Centre may also “lock” sensor check
display by pressing on right hand button on face of Haldex
Info-Centre. The display will show “WHL” to left. You may
then spin wheel and display will show “S2A” to indicate
this sensor is sensing wheel motion. This feature allows
one person to perform this test unassisted.
(3)
Verify driver side sensor is properly connected and positioned by rotating driver side hub or
wheel at rate of approximately 1 revolution every 2 seconds. The Haldex Info-Centre should
display “S2A” while wheel is turning.
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