Bendix MC-11 TRACTOR ANTILOCK User Manual

®
Bendix® MC-11™ Tractor AntiLock
SD-13-4761
DELIVERY
14-PIN
CONNECTOR
CONTROL
SUPPLY
LED DIAGNOSTIC
DISPLAY
EC-11
CONTROLLER
DELIVERY
M-12
MODULATOR
DESCRIPTION
The Bendix® MC-11™ tractor antilock assembly is designed to improve vehicle stability by reducing wheel lock-up during aggressive braking. Like the MC-10™ antilock assembly that it replaces, the MC-11™ tractor antilock assembly is a one-channel system–it uses one modulator. And the system can control single or tandem axles. The antilock assembly mounts to the vehicle frame and usually replaces the drive axle service relay valve.
The MC-11™ tractor antilock assembly consists of an EC-11 electronic controller and an M-12™ modulator. The EC-11 controller houses the electronics that regulate the antilock system. The electronics are protected by a self-healing silicone compound. The EC-11™ controller contains a diagnostic window and reset switch, and its 14 pin connector is the electrical link to the rest of the antilock system. (See Figure 2.) The controller mounts to the modulator with four cap screws, and it is electrically connected to the modulator
with a four-pin connector. The M-12™ modulator has two components: solenoids, which rapidly apply and exhaust air during an antilock stop, and a standard relay valve. (See SD-13-4772 for more information on the M-12™ modulator.)
The air connections for the MC-11™ tractor antilock assembly are as follows:
AIR CONNECTION EMBOSSED
Supply
IDENTIFICATION
(to reservoir) SUP Delivery (to brake actuator) DEL Control (to rear service brake valve delivery) CON
1
14 PIN CONNECTOR CALLOUTS
PIN CONNECTION
A “+” POWER
B RETARDER DISABLE
C “-” GROUND
D DASH LIGHT
E SERIAL LINK
F SERIAL LINK
G UNUSED
H UNUSED
J UNUSED
K UNUSED
L SENSOR
M SENSOR
N SENSOR
P SENSOR
14-PIN CONNECTOR
GROUND
DASH LIGHT
EXH. BLK. PWR
EXH. WHT. PWR
POWER
RETARDER
EXH. BLK. GRD
EXH. WHT. GRD
SENSOR
SERIAL LINK
FIGURE 2 - TYPICAL MC-11™ TRACTOR ANTILOCK WIRING SCHEMATIC
2
14-PIN
CONNECTOR
SENSOR
EXHAUST
SOLENOID
INLET SOLENOID
RESERVOIR
SUPPLY
BRAKE
VALVE
CONTROL
PISTON
DELIVERY
DOUBLE
CHECK VALVE
TRAILER CONTROL
VALVE
EXHAUST
FIGURE 3 - APPLYING: NORMAL SERVICE APPLICATION
The wiring connections on the 14 pin connector are as follows:
PIN A - Power PIN IF - Serial Link
PIN B - Retarder Disable PIN L - Sensor
PIN C - Ground PIN M - Sensor
PIN D - Dash Light PIN N - Sensor
PIN E - Serial Link PIN P - Sensor
PIN A - Vehicle power is supplied to the EC-11™ controller
from the ignition switch, through a fuse, to pin A on the 14 pin connector.
PIN B - The EC-11™ controller is equipped with a retarder
disable circuit, which, when coupled with an electrical relay, will disable the vehicle retarder (engine or transmission) during an antilock stop. The retarder disable function is not essential but is highly recommended for vehicles equipped with a retarder. Connection to pin B on the EC-11
controller provides this function.
PIN C - Pin C connects directly to negative vehicle ground.
PIN D - A dash light and its electrical relay are controlled
by the EC-11™ controller through pin D. The light advises the driver of the antilock system condition.
BRAKE
CHAMBER
PIN E - The serial link allows the EC-11™ controller to “report”
its operating PIN IF condition to a specialized external computer in response to certain commands it receives. The serial link configuration conforms to S.A.E. standard J1708. Pins E and F provide serial link connections to the EC-11™ controller, but the function is not essential for MC-11™ tractor antilock assembly operation.
PIN L - Sensors mounted at the wheel end send wheel
speed information PIN M to the EC-11™ controller through pins L-M and N-P. The EC-11™ controller receives the information at (PIN N) 100 pulses per wheel revolution.
The MC-11™ tractor antilock assembly “knows” what’s happening at the wheel ends because of the signals it receives from the wheel speed sensors. The sensors are actually A.C. generators. They create a magnetic field; and when the field is interrupted by an irregular surface, like a tone ring, A.C. voltage is produced. The frequency of voltage increases or decreases as wheel speed increases or decreases.
During normal, non-antilock operation, the M-12™ modulator inlet solenoid is open, and the exhaust solenoid is closed. In this condition, the M-12™ modulator is a regular R-12 relay valve. It receives a control signal from the foot valve,
3
EXHAUST
SOLENOID
BRAKE
VALVE
DOUBLE
CHECK VALVE
TRAILER
CONTROL
VALVE
INLET SOLENOID
RESERVOIR
SUPPLY
EXHAUST
FIGURE 4 - BALANCED POSITION
which passes through the open inlet solenoid and into the control cavity of the relay valve. The valve then applies air to the service brake chambers in proportion to the control signal.
If wheel lock is impending, the EC-11™ electronic controller commands the solenoids to modulate brake chamber pressure on the axles in which the system is installed.
OPERATION
APPLYING: Normal Service Application
When a normal service brake application is made, control air pressure from the brake valve enters the modulator control port. The air passes through the supply solenoid and acts on the modulator’s piston. The piston closes the modulator exhaust and opens the inlet, delivering supply air out the delivery ports.
BALANCED POSITION: Normal Service Application
CONTROL
PISTON
DELIVERY
BRAKE
CHAMBER
solenoid housing and out the exhaust port of the brake valve. As the piston moves upward, the modulator’s exhaust opens, allowing air from the piston’s underside to exhaust through the modulator exhaust port.
ANTILOCK MODE: Solenoids Activated
If a service brake application is made and the EC-11 controller senses impending wheel lockup, it will command the antilock system to alter the service brake application automatically.
When activated, shuttles within the solenoids alter the application and exhaust of control air pressure. The supply solenoid closes, preventing control line pressure from entering the modulator. Then the exhaust solenoid opens, allowing control pressure to exhaust from the top side of the piston through the exhaust port of the solenoid assembly. This activity occurs in a pulsating manner, simulating “pumping of the brakes.”
The modulator reaches a balanced position when control pressure acting upon the topside of the piston approaches that of the air acting upon the underside of the piston. The piston moves upward and closes the inlet valve, while the exhaust remains closed. This prevents the modulator from delivering or exhausting air.
EXHAUSTING: Normal Service Application
When the brake valve is released, control pressure exhausts through the supply solenoid and the check valve in the
4
PREVENTIVE MAINTENANCE
GENERAL
Perform the inspections and tests at the prescribed intervals. If the MC-11™ tractor antilock assembly fails to function as described, repair or replace the unit.
EVERY 3 MONTHS; 25,000 MILES; 900 OPERATING HOURS; OR DURING THE VEHICLE CHASSIS LUBRICATION INTERVAL
EXHAUST
SOLENOID
DOUBLE
CHECK VALVE
TRAILER
CONTROL
VALVE
BRAKE
VALVE
INLET SOLENOID
RESERVOIR
SUPPLY
EXHAUST
FIGURE 5 - EXHAUSTING: NORMAL SERVICE APPLICATION
1. Remove any accumulated contaminants and visually inspect the exterior of the unit for excessive corrosion or physical damage.
2. Inspect all air lines and wiring connected to the MC-11 tractor antilock assembly for signs of wear or physical damage. Replace as necessary.
3. Perform “LEAKAGE TEST.”
EVERY YEAR; 100,000 MILES; OR 3,600 OPERATING HOURS
1. Perform “OPERATIONAL AND LEAKAGE TESTS.”
OPERATIONAL AND LEAKAGE TESTS
LEAKAGE TEST
1. Park the vehicle on a level surface and block 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. Note that the service brakes apply and release promptly.
3. Build system pressure to governor cut-out and turn engine OFF.
4. Make and hold a full service brake application.
A. Apply a soap solution to the relay valve exhaust port.
A 1" bubble in 3 seconds is permitted.
B. Apply a soap solution to the outside of the modulator
body where the relay valve joins the solenoid assembly. A 1" bubble in 3 seconds is permitted.
CONTROL
PISTON
DELIVERY
BRAKE
CHAMBER
5. If leakage is excessive around the supply and exhaust solenoids, replace the M-12™ modulator.
OPERATIONAL TEST
LED Operation
Although the MC-11™ assembly has self-check diagnostics, the LEDs (Light Emitting Diodes) should be inspected to ensure that they are functioning properly. With the vehicle ignition on, hold a magnet (capable of picking up 3 ounces) to the RESET position on the diagnostic window. All LEDs should illuminate. If one or more of the LEDs do not illuminate, and the dash light indicates proper system function, note the nonilluminated LEDs for future reference. Diagnostic capabilities will be limited, but the system will continue to function as designed.
Solenoid Operation
The MC-11™ assembly monitors the system electronics upon vehicle start-up. However, the vehicle should be tested to verify proper solenoid function. Two technicians will be required to properly test the solenoids.
1. Park the vehicle on a level surface and block the wheels. Release the parking brakes and build the air system to full pressure.
2. Turn the engine ignition key to the OFF position. Then make and hold a full brake application.
5
EXHAUST
SOLENOID
DOUBLE
CHECK VALVE
TRAILER
CONTROL
VALVE
BRAKE
VALVE
INLET SOLENOID
RESERVOIR
SUPPLY
EXHAUST
FIGURE 6 - ANTILOCK MODE: SOLENOIDS ACTIVATED
3. With the brake application held and a technician near the modulator, turn the vehicle ignition key to the ON position. One short burst of air should be noted from the modulator exhaust. If one short burst of air is not noted, or if the exhaust is prolonged and not short, sharp and well-defined, refer to the troubleshooting section.
WARNING! PLEASE READ AND FOLLOW THESE INSTRUCTIONS TO AVOID PERSONAL INJURY OR DEATH:
When working on or around a vehicle, the following general precautions should be observed at all times.
1. Park the vehicle on a level surface, apply the
parking brakes, and always block the wheels. Always wear safety glasses.
2. Stop the engine and remove ignition key when
working under or around the vehicle. When working in the engine compartment, the engine should be shut off and the ignition key should be removed. Where circumstances require that the engine be in operation, EXTREME CAUTION should be used to prevent personal injury resulting from contact with moving, rotating, leaking, heated or electrically charged components.
3. Do not attempt to install, remove, disassemble or
assemble a component until you have read and thoroughly understand the recommended procedures. Use only the proper tools and observe all precautions pertaining to use of those tools.
CONTROL
PISTON
DELIVERY
BRAKE
CHAMBER
4. If the work is being performed on the vehicle’s air brake system, or any auxiliary pressurized air systems, make certain to drain the air pressure from all reservoirs before beginning ANY work on the vehicle. If the vehicle is equipped with an AD-IS air dryer system or a dryer reservoir module, be sure to drain the purge reservoir.
5. Following the vehicle manufacturer’s recommended procedures, deactivate the electrical system in a manner that safely removes all electrical power from the vehicle.
6. Never exceed manufacturer’s recommended pressures.
7. Never connect or disconnect a hose or line containing pressure; it may whip. Never remove a component or plug unless you are certain all system pressure has been depleted.
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.
6
REMOVAL OF THE MC-11™ ASSEMBLY
1. Prior to disassembly, remove as much contamination as possible from the exterior of the assembly. Be sure to keep the contamination away from the open ports.
2. Remove and identify all air lines connected to the unit.
3. Disconnect the 14-pin connector from the unit by unscrewing its hex screw and pulling the connector away from its socket.
4. Remove and save the mounting hardware connecting the MC-11
assembly to the vehicle.
INSTALLATION OF THE MC-11™ ASSEMBLY
1. Replace the MC-11™ assembly on the vehicle using the hardware saved during removal. Connect the air lines to the proper ports, as identified during removal. Connect the 14-pin connector into the controller and tighten the hex screw.
2. Perform “OPERATIONAL AND LEAKAGE TESTS” before placing vehicle back into service.
DISASSEMBLY
The following disassembly and assembly procedure is presented for reference purposes and presupposes that a major rebuild of the antilock valve is being undertaken. Several replacement parts and maintenance kits are available which do not require full disassembly. The instructions provided with these parts and kits should be followed in lieu of the instructions presented here. Refer to Figure 7 throughout the procedure.
CAUTION: The MC-11™ assembly may be lightly clamped in a bench vise during disassembly. However, overclamping will result in damage, leakage, and/or malfunction. If a vise is to be used, position the MC-11™ assembly so the jaws bear on the flat area of the supply port and its opposing side of the body.
1. Remove the EC-11™ controller(1) from the M-12 modulator by removing the controller’s four mounting bolts.
2. Lift the controller off the M-12™ modulator and detach the wire harness from the base of the controller. To detach the harness, depress the tab on the side of the 4-pin connector and pull the connector from its socket in the controller. Remove the gasket(7) from the recess in the EC-11™ controller body. NOTE: If replacement of the controller only is required, proceed to Step 8 of assembly.
3. Remove the four 1/2" bolts that secure the solenoid assembly(2) to the valve body(3). Separate the solenoid assembly and valve body.
4. Remove sealing ring(4) from the protrusion on the bottom of the solenoid assembly.
5. Using a pair of snap ring pliers, remove retaining ring(14). Remove the exhaust assembly(13). Remove o-ring(12) and o-ring(11) from the I.D. and O.D., respectively, of the exhaust assembly.
6. Remove spring(10). Remove the inlet/exhaust assembly(8). Remove the spring seat(9) from the inlet/ exhaust assembly.
7. Using your thumb, press the piston stem and push the piston(6) out the opposite end of the body. Remove o-ring(5) from the piston.
8. Discard all items that have replacement parts in the maintenance kit.
CLEANING AND INSPECTION
1. Using mineral spirits or an equivalent solvent, clean and thoroughly dry all parts to be reused. Do not allow mineral spirits to come into contact with the ECU connector or solenoids.
2. Inspect the interior and exterior of all parts that will be reused for severe corrosion, pitting and cracks. Superficial corrosion and/or pitting on the exterior portion of the body is acceptable.
3. Inspect the bores for deep scuffing or gouges.
4. Inspect the pipe threads in the body. Make certain they are clean and free of thread sealant.
5. Inspect all air line fittings and plugs for corrosion. Clean all old thread sealant from the pipe threads. Any component exhibiting a condition described in inspection steps 2 to 5 should be discarded and replaced before proceeding.
ASSEMBLY
1. Using a lubricant (Bendix Pc. No. 291126) lightly coat all o-rings and the bores of the valve body.
2. Install spring seat(9) onto the inlet/exhaust valve(8) so
that it covers the rubber seat of the inlet/exhaust valve. Place the inlet/exhaust valve, large diameter first, into the M-12™ modulator’s bottom bore.
3. Install spring(10) over the barrel of the inlet/exhaust valve(8) so that one end of the spring rests on the spring seat(9).
4. Install the o-rings(11 & 12) into the respective grooves of the O.D. and I.D. of the exhaust assembly(13). Place the large diameter of the exhaust assembly against the spring(10) and compress the spring until the exhaust assembly enters the bore of the body and the o-ring(11) seals against the wall of the bore.
5. Depress the exhaust assembly into the bore until it exposes the groove for the snap ring(14). Install snap ring(14) into its groove. Make sure it is fully seated.
7
CAP SCREW
1
7
2
4
10
5
6
3
8
9
11
12
13
14
FIGURE 7 - EXPLODED VIEW
8
6. Install o-ring(5) into its groove in the piston(6). Install piston(6) into the M-12™ modulator body. The piston stem fits into the small hole in the center of the body.
7. Install o-ring(4) onto the protrusion on the bottom of the M-12™ modulator solenoid assembly(2). Install the solenoid assembly onto the valve body(3). The solenoid assembly will fit on the M-12™ modulator body in any of four orientations, 90 degrees apart. Secure the solenoid assembly to the valve body with the four 1/2" bolts. Torque the bolts to 120-150 in. lbs.
8. Install gasket(7) onto the EC-11™ controller. Install the EC-11™ controller(1), as shown in Figure 9, by plugging the 4-pin electrical connector from the solenoid assembly into the socket in the bottom of the controller. Press in until lock tab engages. Ensure engagement by pulling the connector lightly. Place the controller on to the solenoid assembly and secure with the four 1/2" bolts and lockwashers. Torque to 30-60 in. lbs.
DIAGNOSING AND LOCATING A SYSTEM PROBLEM
GENERAL
The EC-11™ controller contains self-test and diagnostic circuitry that continuously checks for proper operation of the entire antilock system, including wiring continuity. A dash light, controlled by the EC-11™ controller, advises the driver of the antilock system condition. Specific component condition is provided by a series of Light Emitting Diodes (LEDs) displayed through a “window” in the EC-11™ controller housing.
The dash light’s separation from the EC-11™ controller diagnostic window allows the driver to be aware of any problems that occur but not to be confused by diagnostic information.
A special feature of the MC-11™ antilock system is failure latching. When the controller senses an error, it stores the condition in memory, disables antilock, and illuminates the dash light and the appropriate LEDs on the EC-11™ controller. The condition is truly stored–it is not cleared by loss of power to the EC-11™ controller. The LEDs will re-light when power is restored and will remain illuminated until the problem is corrected. After the actual problem is discovered and corrected, maintenance personnel can clear the EC-11 controller diagnostics by passing a small magnet over the RESET area in the “window.”
DIAGNOSTIC LEDs
There are six LEDs and a magnetic reset switch on the EC-11™ controller diagnostic window.
“VOLT” LED
This red LED illuminates when power to the EC-11™ controller falls outside the acceptable range of 9-18 volts. If the voltage returns to within the acceptable range, the VOLT LED will
RESET
VOLT
MOD
SNS1
SNS2
CONT
PWR
go off. This is the only LED that will reset itself when the failure condition no longer exists.
“MOD” LED
This red LED illuminates AND LATCHES ON when solenoid resistance is not within the acceptable range of 9.5-11.5 ohms. It can also illuminate if excessive electrical spikes are present in the power line.
“SNS 1” AND “SNS 2”
The red SNS LEDs illuminate AND LATCH ON to indicate any one of a number of permanent or intermittent failures. (For example, open or shorted wheel speed sensor, open or shorted sensor wiring, no wheel speed signal.)
“CONT” LED
This red LED illuminates AND LATCHES ON if the EC-11 controller is malfunctioning, or if excessive electrical spikes are present in the power line.
“PWR” LED
This green LED illuminates and remains on during vehicle operation to indicate that vehicle power is reaching the
EC-11™ controller.
TROUBLESHOOTING
GENERAL
While the EC-11™ controller diagnostic display locates a specific problem area, it is still necessary to determine whether the problem resides in the component itself or the wiring. Basically, the troubleshooting procedure that follows is devoted to narrowing down the problem to either the wiring or a specific antilock component.
9
TIPS
1. All troubleshooting should begin by performing the “STARTUP,” which focuses on observing the antilock status light on the dash.
2. The troubleshooting technician should record all findings and the action taken during the troubleshooting process.
3. No voltage or resistance tests are performed into the
EC-11
controller. All electrical tests begin at the wire-harness end of the connector and move AWAY from the EC-11™ controller toward and antilock system component (modulator, wheel speed sensor, etc.).
10
TROUBLESHOOTING
INITIAL START-UP PROCEDURE
TURN VEHICLE IGNITION ON. OBSERVE AMBER DASH LIGHT.
DASH LIGHT NOT ON
GO TO SEC­TION I - DASH LIGHT TEST
DASH LAMP DOES NOT BLINK, IT COMES ON AND REMAINS ON.
GO TO SECTION II ­INSPECTION FOR ILLUMINATED LED(S)
DASH LIGHT STAYS ON
DASH LIGHT FLASHES TWICE AND STAYS ON
ACCELERATE VEHICLE ABOVE 10 MPH FOR AT LEAST 30 SECONDS
DASH LIGHT GOES OFF
GO TO SECTION II ­INSPECTION FOR ILLUMINATED LED(S)
SYSTEM IS FUNCTIONING PROPERLY
11
TROUBLESHOOTING
SECTION I - DASH LIGHT TESTING
DISCONNECT 14 PIN CONNECTOR FROM EC-11™ CONTROLLER OBSERVE DASH LIGHT
GROUND
DASH LIGHT ON
REPLACE EC-11 CONTROLLER
REPEAT STARTUP
DASH LIGHT OFF
RELAY
WITH IGNITION ON, MEASURE VOLTAGE BETWEEN DASH LIGHT RELAY (PIN D) AND GROUND (PIN C). VOLTAGE SHOULD BE SAME AS BATTERY VOLTAGE.
NO
IS VOLTAGE CORRECT?
REPAIR/REPLACE WIRE HARNESS
YES
CHECK WIRING HARNESS AND RELAY FOR SHORTS TO GROUND. RECONNECT AND CHECK/REPLACE
REPEAT STARTUP
THE FOLLOWING:
1. DASH LIGHT BULB
2. FUSE
3. RELAY POWER WIRE
4. RELAY
12
AFTER REPLACING A COMPONENT TEST THE DASH LIGHT.
ON?
TROUBLESHOOTING
SECTION II INSPECTION FOR ILLUMINATED LEDS
INSPECT EC-11™ CONTROLLER FOR ILLUMINATED LED(S)
CHECK FOR GREEN (PWR) LED
GREEN (PWR) LED ON
ARE ANY RED LEDS ON?
YES
NOTE ILLUMINATED LED(S) AND GO TO SECTION III­INSPECTION FOR ILLUMINATED RED LED(S)
ARE ANY ON?
NO
GO TO SECTION VII - FALSE FAIL­URE INDICATION
YES
REPLACE EC-11 CONTROLLER AND REPEAT STARTUP
GREEN (PWR) LED OFF
ARE ANY RED LEDS ON?
GO TO SECTION IV ­TESTING FOR POWER TO EC-11™ CONTROLLER
NO
13
TROUBLESHOOTING
SECTION III - INSPECTION FOR ILLUMINATED RED LEDS
INSPECT EC-15™ CONTROLLER FOR PRESENCE OF ILLUMINATED LEDS AND RECORD.
MOD
CONT
RED CONTROLLER LED (CONT) IS ILLUMINATED
GO TO SECTION IV ­TESTING FOR POWER TO EC-11™ CONTROLLER
RED MODULATOR LED (MOD) IS ILLUMINATED
GO TO SECTION V
- TESTING MODULATOR
RED SENSOR LED (SNS) IS ILLUMINATED
GO TO SECTION VI - TESTING WHEEL SPEED SENSOR
VOLT
SNS
RED VOLTAGE LED (VOLT) IS ILLUMINATED
VOLTAGE LED ILLU­MINATES WHEN POWER TO EC-11™ CONTROLLER FALLS OUTSIDE 9-18 VOLT RANGE. IF VOLTAGE RETURNS TO AN ACCEPTABLE LEVEL. THE LED WILL GO OFF.
14
GO TO SECTION IV
- TESTING FOR POWER TO EC-11 CONTROLLER
MAGNET
HERE TO
RESET
SECTION IV - INSPECTION FOR ILLUMINATED LEDS
YES
RECORD INDICATED RED LED FAILURE (“VOLT” AND/ OR “CONT”
TROUBLESHOOTING
IS THE GREEN (PWR) LED ON?
ON?
NO
PIN A
POWER
TURN IGNITION OFF. DISCONNECT
EC-11™ CONTROLLER
14-PIN CONNECTOR
PIN C
GROUND
PERFORM A RESET
LED(S) OFF
MAY HAVE AN INTERMITTENT FAILURE. CHECK VEHICLE ELECTRICAL SPIKES OR TRANSIENT VOLTAGE
LED(S) OFF
TURN IGNITION ON. MEASURE VOLTAGE BETWEEN PINS A AND C ON THE 14-PIN CONNECTOR.
VOLTAGE
BETWEEN 9-18
VOLTS
REPLACE EC-11
CONTROLLER
VOLTAGE
OUTSIDE 9-18
VOLT RANGE
RECONNECT 14 PIN CONNECTOR. CHECK VEHICLE WIRING. REFER TO VEHICLE SERVICE MANUAL AND CHECK BATTERY. REPAIR/ REPLACE AS NECESSARY
REPEAT STARTUP
15
TROUBLESHOOTING
SECTION V - TESTING MODULATOR
WHITE
MAGNET HERE TO RESET
BLACK
RECORD INDICATED FAILURE. PERFORM A RESET.
“MOD” LED STAYS ON
STILL ON?
DISCONNECT THE 4-PIN
CONNECTOR BETWEEN THE
CONTROLLER AND THE
EC-11
M-12
MODULATOR SOLENOID ASSEMBLY. CHECK RESISTANCE ACROSS BOTH PAIRS OF WIRES.
(WHITE-WHITE, BLACK-BLACK)
“MOD” LED GOES OFF
INTERMITTENT CONNECTION BETWEEN EC-11™ CONTROLLER AND M-12™ MODULATOR. CHECK 4-PIN CONNECTOR
REPEAT STARTUP
CHECK FOR SHORT-BLACK TO CASE GROUND AND WHITE TO CASE GROUND
CONTINUITY
REPLACE M-12
MODULATOR
RESISTANCE WITHIN 9.5-
11.5 OHMS
NO CONTINUITY
REPLACE EC-11
CONTROLLER
RESISTANCE OUTSIDE 9.5-
11.5 OHMS
REPLACE M-12 MODULATOR
16
REPEAT STARTUP
TROUBLESHOOTING
SECTION VI PART A - TESTING WHEEL SPEED SENSOR
NO
CHECK FOR
PRESENCE OF TONE
RING OR MISSING
TONE RING TEETH
CHECK FOR OUT-OF-
SPEC SENSOR GAP
(SHOULD BE 0-.015”)
CHECK FOR
EXCESSIVE WHEEL
BEARING FREE PLAY
STILL ON?
RECORD INDICATED
FAILURE
PERFORM A RESET.
ANY “SNS” LEDS ON?
IF THE OTHER “SNS” LED
ILLUMINATES, A GOOD
SENSOR WAS
DISCONNECTED.
RECONNECT IT AND TEST
THE OTHER SENSOR.
MAGNET HERE TO RESET
YES
OPEN CONNECTOR
FOR EACH SENSOR
AND OBSERVE LEDS.
IF THE OTHER “SNS”
LED DOES NOT
ILLUMINATE, THE
PROBLEM SENSOR
WAS DISCONNECTED.
REPEAT STARTUP
SNS 2
SNS 1
INSPECT FOR BROKEN OR CRIMPED WIRES LEADING TO THE PROBLEM SENSOR. CLEAN CONTACTS AT THE SENSOR AND ITS CONNECTOR.
MEASURE RESISTANCE AT
THE PROPER PIN
LOCATIONS ON THE 14-PIN
CONNECTOR.
(“SNS 1” - PINS N AND P.
“SNS 2” - PINS L AND M.)
GO TO SECTION VI - PART B
17
TROUBLESHOOTING
SECTION VI PART B - TESTING THE MODULATOR
START HERE
RESISTANCE OUTSIDE 1500-2500 OHMS
DISCONNECT SENSOR FROM WIRE HARNESS. MEASURE RESISTANCE ACROSS SENSOR PINS. RESISTANCE SHOULD BE 1500-2500 OHMS.
NO
REPLACE SENSOR
REPEAT STARTUP
YES
CHECK WIRING THAT LEADS TO SENSOR FOR INTERMITTENT CONNECTIONS AND CONTINUITY. REPAIR/ REPLACE AS NECESSARY.
RESISTANCE WITHIN 1500-2500 OHMS
REPLACE EC-11
CONTROLLER
REPEAT STARTUP
18
REPEAT STARTUP
HOLD MAGNET HERE TO RESET
ALL LEDS
SHOULD
BE ON
TROUBLESHOOTING
SECTION VII - FALSE FAILURE INDICATION
NOTE: IF DURING STARTUP, THE DASH LIGHT ILLUMINATED WITHOUT BLINKING, GO TO SECTION VII PART B - TESTING FOR FALSE FAILURE CAUSED BY DASH LIGHT RELAY. I F THE DASH LIGHT BLINKED DURING STARTUP BUT ILLUMINATED AFTER THE VEHICLE REACHED 10 MPH, GO TO SECTION VII PART A - TESTING FOR FALSE FAILURE CAUSED BY WHEEL SPEED COMPONENTS.
HOLD A MAGNET TO THE RESET SWITCH AND MAKE SURE ALL LEDS ILLUMINATE WHEN MAGNET IS PRESENT
LEDS ILLUMINATED?
YES
NO
TONE RINGS PRESENT AND IN GOOD CONDITION
CHECK FOR OUT-OF-SPEC SENSOR GAPS (SHOULD BE 0-.015”)
REMOVE MAGNET
BOTH SENSORS MAY NOT BE RECEIVING SIGNALS.
CHECK FOR PRESENCE OF TONE RINGS.
TONE RINGS NOT PRESENT OR DAMAGED
REPAIR/REPLACE AS NECESSARY.
REMOVE MAGNET
REPLACE EC-11
CONTROLLER
REPEAT STARTUP
GAP OK
REPEAT STARTUP, IF TESTING RETURNS TO THIS PLACE TWICE, REPLACE THE EC-11™ CONTROLLER
GAP OUT
OF SPEC
ADJUST AS NECESSARY
REPEAT STARTUP
19
SECTION VII PART B - TESTING FOR FALSE FAILURE CAUSED BY DASH LIGHT RELAY
HOLD MAGNET HERE TO RESET
ALL LEDS
SHOULD
BE ON
TROUBLESHOOTING
HOLD A MAGNET TO THE RESET SWITCH AND MAKE SURE ALL LEDS ILLUMINATE WHEN MAGNET IS PRESENT
LEDS ILLUMINATED?
YES
NO
TURN IGNITION OFF. CHECK FOR CONTINUITY BETWEEN PIN D AND ITS TERMINAL ON THE DASH LIGHT RELAY.
NO CONTINUITY CONTINUITY
REPAIR/REPLACE WIRE
HARNESS. RECONNECT 14
PIN CONNECTOR AND
REPEAT STARTUP.
REMOVE MAGNET
RECONNECT 14 PIN CONNECTOR. TURN
IGNITION ON AND CHECK
FOR POWER AT THE DASH
LIGHT RELAY COIL.
NO POWER
POWER
FROM PIN D
REMOVE MAGNET
REPLACE EC-11
CONTROLLER
REPEAT STARTUP
CHECK FOR POWER HERE
LIGHT
COIL
RELAY
CHECK DASH WIRING AND
CONNECTORS. CONSULT
VEHICLE MANUAL FOR
FURTHER TROUBLE-
SHOOTING INFORMATION.
REPAIR/REPLACE AS
NECESSARY AND REPEAT
STARTUP.
DASH LIGHT OFF
REPEAT STARTUP, IF TESTING RETURNS TO THIS PLACE TWICE, REPLACE THE EC-11™ CONTROLLER
20
CONNECT OPPOSITE END OF RELAY COIL TO GROUND AND NOTE REACTION OF DASH
GROUND THIS WIRE
COIL
LIGHT.
RELAY
DASH LIGHT ON
REPLACE RELAY
IF LIGHT IS
ON - BAD
REPEAT STARTUP
BW1671 © 2004 Bendix Commercial Vehicle Systems LLC All rights reserved. 4/2004 Printed in U.S.A.
RELAY
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