Bendix Commercial Vehicle Systems TP-5 TRACTOR PROTECTION VALVE 5/11 - Manual (Page 3)

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2. Disconnect the trailer service line hose coupling. Make
a trailer hand control valve application. Cover the 1/16
inch vent hole in the service line shut-off valve area of
the Bendix
® TP-5 ™ valve body. Check for leakage at
hose coupling and at exhaust port at the TP-5 ™ valve.
Excessive leakage at either port indicates a faulty inlet
valve, item 2 on Figure 4.
3. With the hand control valve still applied, turn the ignition
on and check for the stop light function.
4. Release the hand control valve application and place
the tractor protection valve in the normal position.
5. Connect the tractor service hose coupling to a test
gauge, re-apply the hand control valve and note that
there is pressure at the service hose coupling.
6. Check for leakage at the service line quick release
valve. Excessive leakage would indicate a defective
diaphragm (1). See Figure 3.
7. With the service line pressure still applied through the
hand control valve, check for leakage at the brake valve
exhaust. Excessive leakage indicates a defective
double check valve shuttle.
8. Check for leakage at the 1/16 inch vent hole. Leakage
indicates either o-ring (6) or o-ring (5) on the service
line shut-off piston (19) is defective. Note the same size
o-ring is identifi ed as (5) is also used on cap nut (10).
9. Release the hand control valve application and re-check
for leakage at the vent hole. If the leakage continues,
the large o-ring (5) is the cause for the leak and if the
leakage stops, the smaller o-ring (6) is the cause of the
leak.
10. Make and hold a foot brake application. Check for
leakage at exhaust of hand control valve. Excessive
leakage indicates a faulty double check valve shuttle.