TM-9-2320-283-20-1

TRUCK TRACTOR, LINE HAUL, 50,000 GVWR, 6X4, M915A1

TECHNICAL MANUAL; ORGANIZATIONAL MAINTENANCE PART 1 OF 3

DECEMBER 1983

TM-9-2320-283-20-1 - Page 428 of 926

TM 9-2320-283-20-1

TROUBLESHOOTING.

2-11.

TROUBLESHOOTING PROCEDURES (Continued).

MALFUNCTION

TEST OR INSPECTION

CORRECTIVE ACTION

109.

PARK BRAKES WILL NOT RELEASE.

Step 1.

Check reservoir pressure gage and verify that LOW PRESSURE warning lamp is out.

Refer to malfunction 107.

Step 2.

Verify PARK BRAKE manual valve is closed.

Close valve.

Replace valve if it will not close (para 3-171).

Step 3.

Check air lines for leakage or damage.

Use a soap

solution to check for leakage at connections (watch for

bubbles).

Replace damaged lines and tighten loose connections (para 3-163).

Step 4.

Check the air line between forward-rear and rear-rear axle quick release valves for damage or leaks using a

soap solution.

a. Replace line if damaged, and tighten connections (para 3-163).

b. Replace the park brake valve (para 3-171).

110.

TRAILER BRAKES WILL NOT RELEASE.

Step 1.

Check vehicle air hoses for proper connections.

Close trailer supply valve and disconnect hoses.

Reconnect hoses and open supply valve.

Step 2.

Check trailer for air leaks or defective brakes.

Troubleshoot trailer.

2-302