Ram Truck 1500, 2500 & 3500 (2006-2008)

4-Wheel Anti-Lock Brake System

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Bleeding the ABS System



ABS system bleeding requires conventional bleeding methods plus use of the DRB scan tool. The procedure involves performing a base brake bleeding, followed by use of the scan tool to cycle and bleed the HCU pump and solenoids. A second base brake bleeding procedure is then required to remove any air remaining in the system.

  1. Perform base brake bleeding. Refer to the appropriate section.
  2.  
  3. Connect the scan tool to the data link connector beneath the dashboard.
  4.  
  5. Select Antilock Brake followed by Miscellaneous , then ABS Brake . Follow the instructions displayed until the unit displays "Test Complete", then disconnect the scan tool and proceed.
  6.  
  7. Perform a base brake bleeding a second time.
  8.  
  9. Top off master cylinder fluid level and verify proper brake operation before moving vehicle.
  10.  

Control Module



Removal & Installation

Refer to Hydraulic Control Module.

Diagnosis & Testing



Perform ABS verification test as follows:

  1. Turn the ignition off.
  2.  
  3. Connect all previously disconnected components and connectors.
  4.  
  5. Verify all accessories are turned off and the battery is fully charged.
  6.  
  7. Verify that the ignition is on, with the scan tool, erase all Diagnostic Trouble Codes from All modules. Start the engine and allow it to run for 2 minutes and fully operate the system that was indicating the failure.
  8.  
  9. Turn the ignition off and wait 5 seconds. Turn the ignition on and using the scan tool, read DTCs from all modules.
  10.  
  11. If any Diagnostic Trouble Codes are present, return to symptom list and trouble shoot new or recurring symptom.
    NOTE
    For Sensor Signal and Pump Motor faults, the ABM must sense all 4 wheels at 12 km/h (7.5 mph) before it will extinguish the ABS indicator.

  12.  
  13. If there are no DTCs present after turning ignition on, road test the vehicle for at least 5 minutes. Perform several anti-lock braking stops.
  14.  
  15. Again, with the scan tool read DTCs . If any DTCs are present, refer to the Table of Contents in the applicable Section for the diagnostic test procedure and troubleshoot the new or recurring symptom.
  16.  
  17. If there are no Diagnostic Trouble Codes (DTCs) present, and the customer's concern can no longer be duplicated, the repair is complete.
  18.  

General Information



The Four Wheel Antilock Brake System (ABS) is designed to prevent wheel lock-up during braking under virtually any road surface conditions. This allows the driver to retain greater control of the vehicle during braking.

The major components of the system are:



Controller Antilock Brakes (CAB)
 
Hydraulic Control Unit (HCU)
 
Wheel speed sensors
 
ABS warning light
 

The Four Wheel ABS has a three-channel design. The front brake antilock valve provides two channel pressure control of the front brakes. Each front wheel brake unit is controlled separately. Two solenoid valves are used in each control channel.

The rear brake antilock valve controls the rear wheel brakes in tandem. The rear brake valve contains two solenoid valves.

The front and rear antilock valves contain electrically operated solenoid valves. The solenoid valves modulate brake fluid apply pressure during antilock braking. The valves are operated by the antilock electronic module.

The antilock electrical system is separate from other electrical circuits in the vehicle. A specially programmed electronic control module is used to operate the system components.

Some models have Electronic Brake Distribution (EBD) designed into the system which eliminates the combination/proportioning valve.

The ABS electronic control module monitors wheel speed sensor inputs continuously while the vehicle is in motion. The module will not activate the ABS system as long as sensor inputs indicate normal braking.

Click image to see an enlarged view

Fig. ABS schematic-typical

During normal braking, the master cylinder, power booster and wheel brakes units all function as they would in a vehicle without ABS. The solenoid valves are not activated.

The wheel speed sensors converts wheel speed into electrical signals. These signals are transmitted to the module for processing and determine wheel lock-up and deceleration rate. When a wheel speed sensor signal indicate the onset of wheel lock-up the ABS braking is activated.

The antilock system retards the lockup conditions by modulating fluid apply pressure to the wheel brake units. The pressure is modulated according to wheel speed, degree of lock-up and rate of deceleration. The solenoid valves are cycled continuously to modulate pressure. Solenoid cycle time in antilock mode can be measured in milliseconds.

Hydraulic Control Module



Removal & Installation
  1. Before servicing the vehicle, refer to the Precautions Section.
  2.  
  3. Disconnect the battery cables from the battery.
  4.  
  5. Remove the battery.
  6.  
  7. Disconnect the electrical harness connectors.
  8.  
  9. Remove the brake lines from the HCU.
  10.  
  11. Remove HCU/ABM mounting bolts and remove the HCU/ABM from the battery tray.

    Click image to see an enlarged view

    Fig. Hydraulic control unit and Module

  12.  

To install:


NOTE
If the ABM is being replaced with a new ABM is must be reprogrammed with the use of a scan tool.

  1. Install HCU/ABM on the mounts to the battery tray and Tighten the bolts to 15N·m (11 ft. lbs.).
  2.  
  3. Install the brake lines to the HCU (3) and tighten to 170 inch lbs. (19 Nm).
  4.  
  5. Install the electrical harness connectors to the HCU/ABM (3) and push down on the release to secure the connectors.
  6.  
  7. Install the battery.
  8.  
  9. Install the battery cables to the battery.
  10.  
  11. Bleed ABS brake system.
  12.  

Wheel Speed Sensor Rings (Toothed Rings)



The "tone wheel" works in conjunction with the front wheel speed sensors as part of the ABS. There is one on each wheel.

The tone wheel is located on the hub/bearing , on the axle outer stub shaft or inside the hub/bearing housing, depending on model and equipment.

This component is not serviceable or removable and if damaged, the assembly of which it is a part must be replaced.

Wheel Speed Sensors



Front Wheel Speed Sensors
Removal & Installation
2-Wheel Drive
  1. Before servicing the vehicle, refer to the Precautions Section.
  2.  
  3. Raise and support the vehicle.
  4.  
  5. Remove the sensor bolt from the steering knuckle/hub and remove the sensor.
  6.  
  7. Disconnect the ABS wheel speed sensor wire and detach the wire from securing clips.
  8.  

To install:

  1. Tighten the sensor bolt to 17 ft. lbs. (23 Nm).
    NOTE
    Use the original or replacement sensor bolt only. The bolt is special and must not be substituted.

  2.  
  3. The remainder of the procedure is the reverse of removal.
  4.  

4-Wheel Drive Models
  1. Before servicing the vehicle, refer to the Precautions Section.
  2.  
  3. Raise and support the vehicle.
  4.  
  5. Remove the wheel.
  6.  
  7. Remove the brake caliper.
  8.  
  9. On 8-stud wheels, remove the rotor hub bearing assembly and separate the rotor from the hub bearing.
  10.  
  11. On other wheels, remove the rotor.
  12.  
  13. Remove the sensor attaching bolts.
  14.  
  15. Disconnect the wire and remove the sensor from the vehicle.
  16.  

To install:

  1. Tighten the bolts to 13 ft. lbs. (18 Nm).
    NOTE
    Use the original or replacement sensor bolts only. The bolts are special and must not be substituted.

  2.  
  3. The remainder of the procedure is the reverse of removal.

    Click image to see an enlarged view

    Fig. Front wheel speed sensor installation-4WD

  4.  

Rear Wheel Speed Sensors
Removal & Installation
  1. Before servicing the vehicle, refer to the Precautions Section.
  2.  
  3. Raise the vehicle on a hoist.
  4.  
  5. Disconnect the wheel speed sensor electrical connector.
  6.  
  7. Remove the mounting bolt from the sensor.
  8.  
  9. Remove the sensor from the brake caliper adapter.

    Click image to see an enlarged view

    Fig. Rear wheel speed sensor view

  10.  

To install:

  1. Insert the wheel speed sensor in the brake caliper adapter.
  2.  
  3. Install the sensor mounting bolt and tighten to 200 in. lbs. (24 Nm).
  4.  
  5. Reconnect the electrical wiring connector to the sensor.
  6.  
  7. Lower the vehicle.
  8.  

 
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