Table 4-2. Unit Troubleshooting (cont'd)
TEST OR INSPECTION
10. BRAKES WILL NOT RELEASE
Step 1. Check for restrictions in air lines and hoses.
If air lines or hoses are restricted, replace as required.
If air lines and hoses are not restricted, proceed to step 2.
Step 2. Check to see if shutoff valves in towing vehicle are open.
If valves are closed, open shutoff valves.
If valves are open, proceed to step 3.
Step 3. Check to see if any drain cock is open.
If any drain cock is open, close drain cock.
If all drain cocks are closed, proceed to step 4.
Step 4. Check for intervehicular air hoses (1) for proper connection and damaged or missing
preformed packing (2).
If hoses are improperly connected, connect them properly. If preformed packing is
missing or damaged, replace packing.
If hoses are properly connected and preformed packing is good, proceed to step 5