7
8.
Use only genuine Bendix
®
replacement parts,
components and kits. Replacement hardware,
tubing, hose, fittings, etc. must be of equivalent
size, type and strength as original equipment and
be designed specifically for such applications and
systems.
9. Components with stripped threads or damaged
parts should be replaced rather than repaired. Do
not attempt repairs requiring machining or welding
unless specifically stated and approved by the
vehicle and component manufacturer.
10. Prior to returning the vehicle to service, make
certain all components and systems are restored
to their proper operating condition.
11. For vehicles with Antilock Traction Control (ATC),
the ATC function must be disabled (ATC indicator
lamp should be ON) prior to performing any vehicle
maintenance where one or more wheels on a drive
axle are lifted off the ground and moving.
PREVENTIVE MAINTENANCE
GENERAL
Perform the tests and inspections presented at the prescribed
intervals. If the modulator fails to function as described, or
leakage is excessive, it should be replaced with a new Bendix
unit, available at any authorized parts outlet.
EVERY MONTH, 10,000 MILES OR 350
OPERATING HOURS
1. Remove any accumulated contaminates and visually
inspect the exterior for excessive corrosion and physical
damage.
2. Inspect all air lines and wire harnesses connected to
the modulator for signs of wear or physical damage.
Replace as necessary.
3. Test air line fittings for leakage and tighten or replace as
necessary.
4. Perform the ROUTINE OPERATION AND LEAKAGE
TESTING described in this manual.
OPERATION & LEAKAGE TESTS
LEAKAGE TESTING
1. Park the vehicle on a level surface and block or chock
the wheels. Release the parking brakes and build the
air system to full pressure.
2. Turn the engine OFF and make 4 or 5 brake applications
and note that the service brakes apply and release
promptly.
3. Build system pressure to governor cut-out and turn the
engine OFF.
4. After determining the pressure loss with the brakes
released (2 PSI/minute allowed), make and hold a full
service brake application. Allow the pressure to stabilize
for one minute.
5.
Begin timing pressure loss for two minutes while watch-
ing the dash gauges for a pressure drop. The leakage
rate for the service reservoirs should not exceed 3 PSI/
minute.
6.
If either circuit exceeds the recommended two PSI/
minute, apply soap solution to the exhaust port of the
modular and any other components in the respective
circuit.
7.
The leakage at the exhaust port of most Bendix compo-
nents, including M-30
™
modulators, should not exceed
a one-inch bubble in three seconds. If leakage at the
modulator is determined to exceed the maximum lim-
its, replace the modulator.
OPERATION TESTING
To properly test the function of the modulator will require two
(2) service technicians.
1. Park the vehicle on a level surface and block or chock
the wheels. Release the parking brakes and build the
air system to governor cut out.
2. Turn the engine ignition key to the OFF position then
make and hold a full brake application.
3. With the brake application held and one (1) service
technician posted at one (1) of the modulators, turn the
vehicle ignition key to the ON position. ONE OR TWO
SHORT bursts of air pressure should be noted at the
modulator exhaust. Repeat the test for each modulator
on the vehicle. If at least a single burst of exhaust is not
noted or the exhaust of air is prolonged and not short,
sharp and well defined, perform the Electrical Tests.
ELECTRICAL TESTS
1. Before testing the solenoid assembly of a suspect
modulator, its location on the vehicle should be confirmed
using the Troubleshooting or Start Up procedure for the
specific antilock controller in use. (See the Service Data
Sheet for the antilock controller for this procedure.)
FIGURE 11 - M-30
™
MODULATOR CONNECTOR VIEWS
Electrical
Connector
43
Exhaust
41
Source
42
Hold
