TM 9-2320-272-24-1
Table 2-4. Compressed Air and Brake System Troubleshooting (Contd).
MALFUNCTION
TEST OR INSPECTION
CORRECTIVE ACTION
17. WARNING BUZZER FAILS TO SOUND OR FAILS TO SHUT OFF ON LOW PRESSURE (BELOW 55-65 PSI
(379-448 kPa)), AIR PRESSURE SYSTEM OPERATING NORMALLY
See Electrical Troubleshooting, para. 2-22.
END OF TESTING!
18. SPRING BRAKES DO NOT RELEASE (VEHICLE BRAKES GRAB OR DRAG)
NOTE
If only one spring brake chamber fails to release, perform
malfunction 5.
Test 1. Isolate malfunction.
Full out emergency spring brake release control (1) and move vehicle forward to determine if
spring brakes release.
a. If spring brakes release, perform test 2.
b. If spring brakes do not release, perform tests 2, 3, and 4.
Test 2. Check supply pressure to parking brake valve (4).
Step 1. Inspect parking brake valve (4) to determine if mechanical actuator (2) is stuck in
engage position.
a. If actuator (2) is sticking, pull back rubber boot (3) and apply a few drops of light
machine oil (Appendix C, Item 47) to actuator (2).
b. If malfunction continues, go to step 2.
Step 2. Start engine and allow air system to build to normal operating pressure.
WARNING
Loosen supply line at valve very slowly. Stop procedure and
tighten fitting of supply line the moment air begins to escape.
Injury to personnel may result if line is accidentally disconnected
from valve.
a. Slowly loosen supply line (5) to check for air pressure.
b. If pressure is not present, proceed to test 3.
c. If pressure is present, proceed to test 4.
2-210
