Bendix Commercial Vehicle Systems MC-12 MODULATOR CONTROLLER ASSY - Manual (Page 16)

16
Troubleshooting
SECTION VI PART A
TESTING THE WHEEL SPEED SENSOR
START HERE
REPEAT THE "INITIAL START-UP
PROCEDURE
ARE ANY RED LEDs
ILLUMINATED?
GO TO SECTION III - "INSPECTION
FOR ILLUMINATED LEDs"
NO
YES
GO TO SECTION VI PART B
AND BEGIN TESTING
ANY RED LED's ON?
NO
TURN IGNITION ON & APPLY & HOLD
BRAKES ON. PASS MAGNET OVER
"RESET" ON EC-12 ™ CONTROLLER.
REMOVE MAGNET AND OBSERVE
THE LEDs.
RECONNECT EC-12 ™ CONTROLLER CONNECTOR, TURN
IGNITION ON & APPLY & HOLD BRAKES ON. PASS
MAGNET OVER "RESET" ON EC-12 ™ CONTROLLER.
REMOVE MAGNET AND OBSERVE LEDs
YES
A B C D E F G H J K L M N P
M -SNS 2
L-SNS 2
N-SNS 1
P-SNS 1
TESTING SPEED SENSOR RESISTANCE
MAGNET HERE
RESETTING
EC-12 ™ CONTROLLER
MAGNET HERE
RESETTING EC-12 ™
CONTROLLER
EC-12 ™ CONTROLLER WIRE
HARNESS CONNECTOR
TURN IGNITION OFF, DO NOT APPLY BRAKES AND CHECK FOLLOWING:
A. REMOVE CONNECTOR FROM EC-12 ™ CONTROLLER AND MEASURE
RESISTANCE BETWEEN SPEED SENSOR M & L AND N & P. RESISTANCE
FOR BENDIX ® WS-20 ™ SPEED SENSOR SHOULD BE BETWEEN 1500-2500
OHMS. REFER TO VEHICLE MAINTENANCE MANUAL IF OTHER THAN THE
WS-20 ™ SPEED SENSOR IS IN USE. IF RESISTANCE NOT CORRECT,
DISCONNECT CONNECTOR AT SPEED SENSOR. INSPECT CONNECTOR,
THEN CHECK RESISTANCE BETWEEN PINS ON SENSOR. IF RESISTANCE IS
NOT CORRECT (BETWEEN 1500-2500 OHMS FOR THE BENDIX ® WS-20 ™
SPEED SENSOR), REPLACE SENSOR, OTHERWISE PROCEED TO STEP B.
B. CHECK “GAP” BETWEEN SPEED SENSOR AND EXCITER OR TONE RING.
(GAP FOR BENDIX ® WS-20 ™ SPEED SENSOR, SPEED SENDER IS BETWEEN 0
- .015 INCHES) IF SENSOR GAP MUST BE ADJUSTED, CHECK FOR LOOSE
OR WORN WHEEL BEARINGS BEFORE RE-GAPPING SENSOR. REFER TO
VEHICLE MAINTENANCE MANUAL FOR WORN BEARINGS.
C. IF SENSOR GAP IS CORRECT CHECK WHEEL BEARING FOR FREE PLAY TO
VERIFY IT COMPLIES TO MANUFACTURER’S RECOMMENDATIONS.
D. MAKE CERTAIN EXCITER OR TONE RING IS IN PLACE AND INSPECT
CONDITION. CHECK FOR MISSING OR DAMAGED TEETH AND THAT IT RUNS
TRUE AND PERPENDICULAR TO SENSOR FACE.
E. CHECK WIRING HARNESS AND CONNECTORS THAT RUN TO SENSOR.
F. CHECK FOR DRAGGING BRAKES (OVER ADJUSTED, TRAPPED AIR IN
ACTUATOR, OUT OF ROUND DRUMS, FAULTY RETURN SPRINGS, PARKING
BRAKE SYSTEM FAULTS, ETC.) AND CORRECT AND RETEST.