BENDIX BW1742 User's Manual
Contents
1. Troubleshooting The Bendix MC 12 Trailer AntiLock System Pre 2 98 sPINSTYLE STATUS INDICATOR CONNECTOR Optional 7 PIN CONNECTOR Ground Front Constant Power Ground Stop Light Power Status Light Stop Lamp Sw ANTILOCK Bendix INDICATOR Brakes MC 12 Modulator Controller Ref SD 13 4762 IF INDICATOR REMAINS ILLUMINATED SYSTEM REQUIRES SERVICE WHEEL SPEED SENSOR G CONNECTOR Resistance Across Pins 1500 2500 ohms Ref SD 13 4754 Wheel Speed Sensor Mounting Block TYPICAL TRAILER AXLE OPERATIONAL INFORMATION The EC 12 controller houses the electronics that regulate the antilock system The EC 12 contains a diagnostic window and a 14 pin connector Diagnostic Window The EC 12 mounts on the M 12 modulator with four bolts and it is internally connected to the solenoids by a four pin connector Sensors mounted at the wheel end send wheel speed information to the EC 12 through the 14 pin connector If wheel lock up is impending the EC 12 commands the solenoids to modulate brake chamber pressure on the axle s on which the system is installed The MC 12 modulator controller receives power from the 7 pin tractor to trailer connector at the nose of the trailer The ground connection to the EC 12 is also from the 7 pin connector During start up when the trailer brakes and stop lights are actuated trailer antilock immediately runs a self check The trailer2. hite Black to Black e Improperly spliced connection repair or repair not sealed properly e Excessive sensor air gap sensor bushing tension or excessive bearing end play MODULATOR Gently push sensor against exciter ring or readjust bearings e Non functioning antilock components sensor controller modulator Additional Servicing Tips e Gently probe terminals when checking for resistances do not deform contacts e Apply nonconductive dielectric grease to any and all connectors if inspecting or disconnecting connectors e If excessive cable length is present bundle and tie wrap ss o_O VOLTAGE neatly to adjacent airlines or framing members ans EE w STOP e Do not pierce wires with probes when LAMP roubleshooting harnesses PONEN PNMLKJH GFEDCBA A C 9to18VoltsDC lt B C 9to18 Volts DC ECU CONTROLLER Replace Controller ADDITIONAL INFORMATION 1 800 247 2725 BW1742 Honeywell 5 98 Printed in U S A ALL CONTACT OF THE 14 PIN CONNECTOR ABOVE SHOULD 2 WI E NOT HAVE ANY CONTINUITY TO THE GROUND CONTACT C CONTACTS A amp B ARE POWER TO THE MC 12
3. status light if so equipped flashes once and then goes off Should a problem occur the status light comes on and remains on TROUBLESHOOTING If the status light remains on with power applied inspect the EC 12 for illuminated LEDs The status light is an optional feature in the trailer antilock system If no status light is present the diagnostic LEDs should be checked periodically Reset controller with magnet after repair Bendix CHECK THE VEHICLE WIRING HARNESS CONNECTOR IF THESE LED S FOR THE PROPER RESISTANCE WITH MC 12 Controller Cable Assembly ARE ILLUMINATED STOP LAMP POWER OFF Status Light To Controller Stop L Power Ground Constant Power SENSOR 1 Sensor 2 PNMLKJH GFEDCBA Sensor 2 ol i Bee ee Sensor 1 ae Sensor 1 Vehicle wire harness Old New Old Style Connectors do not have a Constant Power terminal Style Style SENSOR 2 Most Commonly Encountered Problems That Result In LEDs Being Illuminated PNMLKJH GFEDCBA Repair or Replace Components As Necessary L M 15 2500 Ohms e Damaged connectors or wires caused by dangling or loose wires not properly restrained e Power connection not capable of supplying 12 volts at 3 amps because of a poor connection bad crimp 9 5 11 5 9 5 11 5 e Corroded connectors and connections not properly sealed or seated Ohms Ohms e Terminals not completely latched or sealed into connectors harness connector bolt not tight White to W
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