Hino 600, Workshop Manual, Page: 293 / 451

SERVICE BRAKE (FULL AIR BRAKE) BR02–15
4. Constant exhaust of air at
air dryer purge valve
exhaust or unable to build
system pressure. (Charge
mode.) A. Air dryer purge valve leak-
ing excessively. A. With compressor loaded, apply soap solution on
purge valve exhaust, to test for excessive leakage.
Repair or replace purge valve as necessary. Refer
to Technical Bulletin TCH-008-040.
B. Purge valve frozen open -
faulty heater and thermo-
stat, wiring, blown fuse. B. Refer to paragraph 5 of Operation and Leakage
Tests for heater and thermostat test.
C. Defective AD-IS

air
dryer delivery check
valve.
C. Refer to Symptom 1, Remedy B.
D. Leaking Turbo Cut-Off
valve. D. Repair or replace purge valve assembly.
E. Defective governor. E. Check governor at both "cut-in" and "cut-out" posi-
tion for (i) proper pressures and (ii) excessive leak-
age at fittings and exhaust.
F. Leaking purge valve con-
trol piston quad-ring. F. Repair or replace purge valve assembly.
5. Cannot build system air
pressure. A. Kinked or blocked
(plugged) discharge line. A. Check to determine if air passes through dis-
charge line. Check for kinks, bends, excessive car-
bon deposits, or ice blockage.
B. Excessive bends in dis-
charge line (water collects
and freezes). B. Discharge line should be constantly sloping from
compressor to air dryer with as few bends as pos-
sible.
C. Pressure protection
valve(s) in air dryer will
not open. C. Replace air dryer (pressure protection valves are
not serviceable).
D. Refer to Symptom 4. D. Refer to Symptom 4, Remedy A.
E. Refer to Symptom 7. E. Refer to Symptom 7, Remedies A and B.
6. Air dryer does not purge or
exhaust air. A. Faulty air dryer purge
valve. A. After determining air reaches purge valve control
port by installing a T-fitting with a pressure gauge
into the governor unloader port, repair purge valve
if necessary.
B. See Causes B, E, and F
for Symptom #4. B. Refer to Symptom 4, Remedies B, E, and F. Also
refer to Symptom 1, Remedy B.
7. Desiccant material being
expelled from air dryer
purge valve exhaust (may
look like whitish liquid or
paste or small beads.) A. Faulty dryer cartridge. A. Replace AD-IS

air dryer cartridge and/or AD-IS

air dryer.
B. Excessive dryer vibration. B. Check the AD-IS

air dryer mounting for loose-
ness or damage. Repair mounting and replace car-
tridge.
8. Unsatisfactory desiccant life. A. Excessive system leak-
age. A. Refer to Symptom 1, Remedy A.
B. Wrong vehicle application
for AD-IS

air dryer.
B. Refer to Symptom 2, Remedy C.
C. Compressor passing
excessive oil. C. Check for proper compressor installation; if symp-
toms persist, replace compressor. Refer to Bendix
Advanced Troubleshooting Guide for Air Brake
Compressor (BW1971).
SYMPTOMS CAUSE REMEDY