TRAILER BRAKES DO NOT RELEASE (Cont)

TM 9-2320-285-24-1

2-49.

TRAILER BRAKE LINES AND COUPLINGS TROUBLESHOOTING (CONT)

MALFUNCTION

TEST OR INSPECTION

CORRECTIVE ACTION

1. TRAILER BRAKES DO NOT RELEASE (Cont)

Step 4.

Remove glad hands from emergency (red) and service (blue) trailer

hoses and install calibrated air pressure gage on each hose.

Depress tractor protection valve.

Test gage on red hose should indicate air system pressure (same as

AIR PRESS gage indication).

Test gage on blue hose should indicate zero psi.

a. If test gage on red hose indicates zero psi and test gage on blue hose indicates air system

pressure, hoses are crossed at tractor protection valve; reconnect (para 2-53a).

b. If test gage on red hose indicates air system pressure and test gage on blue hose indicates zero

psi, go to Malfunction 2 below.

c. If both test gages indicate zero psi, notify direct support maintenance.

2. TRAILER SERVICE BRAKES DO NOT FUNCTION (CAB GUARD)

Step 1.

Remove glad hands from emergency (red) and service (blue) trailer air hoses and install calibrated

air pressure gage on each hose. With the tractor air system pressure at 100 psi, depress tractor

protection valve. Test gage on red hose should indicate air system pressure (same as AIR PRESS

gage indication). Depress the brake treadle valve fully and watch pressure gage on blue hose. Test

gage on blue hose should indicate air system pressure (same as AIR PRESS gage indication).

a. If indication of test gage on blue hose agrees to within 10 psi of AIR PRESS gage indication, go

to step 2 below.

b. If indication of test gage on blue hose differs by more than 10 psi from AIR PRESS gage

indication, notify direct support maintenance.

Step 2.

Remove glad hands from emergency (red) and service (blue) trailer air hoses and install calibrated

air pressure gage on each hose. With the tractor air system pressure at 100 psi, depress tractor

protection valve. Test gage on red hose should indicate air system pressure (same as AIR PRESS

gage indication). Pull trailer hand brake control all the way down. Test gage on blue hose should

indicate air system pressure (same as AIR PRESS gage indication).

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