BENDIX MC-30 TRAILER ABS CONTROLLER Manual page 31

SECTION H - TROUBLESHOOTING ABS MODULATORS
MOD LED and ABS indicator lamp
are on.
Make repairs to wiring or replace
ABS modulator-valve. Reconnect all
connectors to the MC-30
and M-30T ™ modulator-valve. Reset
fault codes by briefl y holding a magnet
in place at the RESET location of the
diagnostic display. Then rerun the
power up sequence.
Go to Section A.
Make repairs to ABS modulator-
valve installation or wheel end.
Reconnect all connectors to the
™
MC-30 controller and M-30T
modulator-valve. Reset fault codes
by briefl y holding a magnet in place at
the RESET location of the diagnostic
display. Then rerun the power up
sequence. Go to Section A.
30-Pin Connector
K J H G F
J2 Modulator 1 Hold
H3 Modulator 1 Common
J3 Modulator 1 Exhaust
H2 Modulator 2 Hold
J1 Modulator 2 Common
K1 Modulator 2 Exhaust
™ controller
™
1
2
3
E D C B A
E1 Ignition Power
E3 Brake Light Power
D2 Ground
Turn off power to the MC-30
and remove the 30-pin connector.
Static ABS Modulator Faults -
Verify 7.0 to 10.0 OHMS across Hold
and Common connector pins. Verify
7.0 to 10.0 OHMS across Exhaust/
Common connector pins. Verify 14.0
to 20.0 OHMS across Exhaust/Hold
connector pins. Verify no continuity
from modulator connector pins to
ground. Verify ignition power is not
YES
measured at any modulator connector
pins. Check for corroded or damaged
modulator wiring and connections.
If a circuit fault is found, isolate the
area needing repair by repeating the
measurements at all connections in
the ABS modulator circuit.
ABS modulator fault identifi ed?
Dynamic ABS Modulator Faults
- Verify proper modulator-valve
activation with brake pressure applied,
at power-up (Chuff Test) and/or using
diagnostic tool. The wiring to the
modulator may be reversed. Check
for dragging brakes, dry bearings,
faulty return springs, parking brake
system faults, restricted brake air
lines, over adjusted slacks, out of
round drums or damaged/loose tone
rings.
Electrical connector on the
™
M-30T modulator-valve.
A
Hold Common
™
controller
NO
B C
Exhaust
31