4-15. AIR SYSTEM TROUBLESHOOTING PROCEDURES (CONT).
6. DRAWBAR RAISES WITHOUT OPERATION.
Tools and Special Tools
Tool Kit, General Mechanic's: Automotive
(Item 50, Appendix J)
Engine OFF, (TM 9-2320-364-10)
Parking brake applied, (TM 9-2320-364-10)
Wheels chocked, (TM 9-2320-364-10)
Charging hose connected to trailer
quick disconnect and truck, (Para 2-9 or 2-11)
Trailer air system charged, (Para 2-22)
There are two models of drawbar assist control valves. Model B replaced Model A.
Model A has air lines on top of valve and uses elbow and reducer fittings.
Model B has air lines on back of valve and uses straight adapter fittings.
Truck air system OK.
Are lines 2224, 2225, 2226,
2231, 2232 and fittings free
REASON FOR QUESTION
of crimps or blockage?
Air lines and fittings faulty.
If air lines are crimped or
Air bag control valve faulty.
blocked, air pressure will not
Relief valve faulty.
release from air bag.
Repair or replace air
lines and fittings (see
schematic Fig FO-2 or
Para 4-47). Verify
repair, go to Step 3 of