TM-9-2320-272-23-2
TRUCK, 5-TON, 6X6, M939, M939A1, AND M939A2 SERIES TRUCKS (DIESEL)
TECHNICAL MANUAL; FIELD MAINTENANCE MANUAL; VOLUME 2 OF 5
SEPTEMBER 2012
TM-9-2320-272-23-2 - Page 77 of 1417
TROUBLESHOOTING ABS WITHOUT DIAGNOSTIC TOOLS - Continued
STEP
13.
IS THE 15 AMP FUSE OK?
a.
Turn battery switch ON.
b.
Turn start switch to RUN.
c.
Locate the red conductor wire from the ABS harness under the vehicle dash.
d.
Disconnect the jumper lead from the red wire.
e.
Connect multimeter red lead to jumper lead terminal. Refer to point to point schematics.
f.
Connect multimeter black lead to a known good ground.
g.
Meter reading should be between 21 and 24 VDC.
CONDITION/INDICATION
IS THE 15 AMP FUSE OK?
DECISION
NO - Repair or replace 15 amp fuse or jumper wire (Volume 3, WP
0464). Go to Step (15) to verify problem is
solved.
YES - Go to Step (14).
STEP
14.
IS THERE EVIDENCE OF AN AIR LEAK FROM A BRAKE SYSTEM COMPONENT?
a.
Start vehicle and build air supply to normal operating pressure.
b.
Assistant fully applies and holds service brakes.
c.
Listen for and locate any air leaks. Refer to point to point schematics.
CONDITION/INDICATION
IS THERE EVIDENCE OF AN AIR LEAK FROM A BRAKE SYSTEM COMPONENT?
DECISION
YES - Replace damaged air lines (Volume 5, WP
0805). Go to Step (15) to verify problem is solved.
NO - Notify supervisor. It is possible that another troubleshooting work package applies.
STEP
15.
IS YOUR ORIGINAL PROBLEM STILL PRESENT?
a.
Ensure vehicle is returned to normal operating condition.
b.
Start vehicle.
c.
Operate vehicle to a speed of 20 miles per hour.
d.
Make one quick hard stop to initiate an ABS event.
e.
Check of ABS warning lamp comes on while operating vehicle.
f.
Return vehicle to park position.
g.
Shut off engine.
TM 9-2320-272-23-2
0156
0156-14
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