Dodge Colt/Challenger/Conquest/Vista 1971-1989 Repair Guide

Rear Brake Lock-Up Control System

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The late model Conquest is equipped with a rear wheel lock-up control system that is designed to achieve maximum braking efficiency for quick stops on wet or icy roads, and to reduce the possibility of vehicle skidding causes by rear wheel lock-up.

The rear wheel lock-up system is composed of five units, which are: A pulse generator. A G-sensor. A control unit. A modulator. And a fail indication light. The pulse generator generates a rotation pulse in accordance with the speed of the rear wheels. The G-sensor generates a voltage in accordance with the reduction of the vehicle speed. The control unit controls each of the signals received from the pulse generator and G-sensor. The modulator controls the brake fluid pressure. The fail indication light warns of a malfunction in the control unit.

REMOVAL & INSTALLATION



Modulator
  1. The modulator is located on the passenger's side fender well. Remove the heat protector.
  2.  
  3. Remove the vacuum lines, the brake fluid lines and the solenoid wiring harness.
  4.  
  5. Disconnect the mounting brackets and remove the modulator.
  6.  
  7. Service as required. Mount the modulator in position and connect the lines and wiring harness. Bleed the brake system.
  8.  

Bleed the modulator before bleeding the front wheels.

  1. If the modulator solenoid is suspected improper operation check the resistance value between the electrical terminals with an ohmmeter. On the solenoid release side: Terminals 1 and 3, resistance should measure 3.8-4.8 ohms. On the build up side: Terminals 2 and 4, the resistance should measure 4.5-5.5 ohms. Service as required.
  2.  

G-Sensor
  1. The G-Sensor is located in the luggage compartment.
  2.  
  3. Disconnect the wiring harness and remove the mounting bolts and the sensor.
  4.  
  5. Install the G-Sensor and connect the wiring harness.
  6.  

When handling the G-Sensor, be careful not to subject it to any impact or violent shaking.

  1. While the G-Sensor is mounted, check the voltage across the R wire and ground. Voltage should be 7.0-7.5 volts. If voltage is not within specs, the control unit should be suspect.
  2.  

Control Unit
  1. The control unit is located under the side panel on the right side of the luggage compartment.
  2.  
  3. Remove the mounting screws, lower the unit and disconnect the wiring harness.
  4.  
  5. Connect the wiring harness and mount the control unit in position with the mounting screws.
  6.  

Pulse Generator
  1. The pulse generator is mounted on the transmission side of the speedometer cable.
  2.  
  3. Disconnect the speedometer cable and wiring. Look for mating marks between the generator housing and the transmission. If none are seen, scribe a pair (on generator and transmission). Remove the clamp bolt and remove the pulse generator.
  4.  
  5. Align the mating marks and mount the pulse generator with the clamp. Be sure the clamp is positioned in the grooves provided in the generator body. Connect the speedometer cable and wiring.
  6.  
  7. The resistance between the terminals of the pulse generator should be 600-800 ohms.
  8.  

Control Relay
  1. The control relay is located on the left front cowl side of the vehicle.
  2.  
  3. Disconnect the wiring harness and unbolt the relay.
  4.  
  5. Mount and secure the relay in position and connect the wiring harness.
  6.  

 
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