Module, Electric Park Brake: Operation: Operation

The Electric Park Brake module receives 12 volt constant power and 12 volt key on ignition signal power. It controls the on/off output command for the Electric Park Brake (EPB), the electromechanical motor gear unit that drives both rear brake caliper pistons during park brake mode.

Input to the EPB module for the on/off action is received from the EPB switch and a CAN-C bus message from the Electronic Vehicle Information Center (EVIC), U-Connect®, Electronic Stability Control (ESC), and other controllers including the Scan Tool (For Service Mode).

The output of the module is controlled by the following normal conditions:

Manual Apply 

• The EPB module will apply the parking brakes when the EPB switch is pulled and the vehicle is at a stop (Ignition On or Off). The EPB module can also apply the brakes while the vehicle is moving if you maintain pulling the switch to request a dynamic apply, where hydraulic braking is actuated via ESC control.

Manual Release 

• EPB module will release the EPB with the vehicle in IGN/RUN position, brake pedal is applied, and the EPB switch is pushed.
  NOTE:

  If the brake pedal is hard to move it may be necessary to start the vehicle. 

Auto Park Brake 

• The EPB will apply when the vehicle is moved into the "park" position or whenever the ignition is turned "off" with a manual transmission. This occurs when the driver selects this option from the Uconnect settings menu for Customer selectable EPB functions. On a vehicle without a touchscreen the EPB settings are located in the cluster's EVIC display.

Drive Away Release 

• When in any drive gear, the EPB module will automatically release the EPB when throttle input and engine torque is detected. Also the EPB confirms the drivers seat belt is fastened and the brake pedal is not being pressed.

Safe Hold 

• If the EPB module detects that the vehicle is capable of movement without driver presence it will actuate the EPB. This is hard programmed into the module and is not able to be turned off. It can be by-passed, by performing a manual release while conditions for SafeHold are still true. The by-pass will reset with an ignition cycle or once the vehicle achieves 20 KPH (12MPH). Safe Hold conditions:
  • Ignition left in the Run/on position.
  • Transmission not in park.
  • Door open.
  • Drivers seat belt unfastened.
  • No throttle or brake pedal in put and the vehicle is stationary/static.

Loss of Voltage 

• EPB module is not able to manually release or apply EPB when voltage is lost or below 10.5V at the vehicle battery.

External Apply 

• Other vehicle systems can request the EPB module (such as ABS module) to apply the EPB if necessary to secure vehicle.

Service Mode 

• The EPB module can be commanded to retract the EPB (actuators) through the U-Connect™ (customer usable method) and through the Scan Tool. On vehicles without the touchscreen radio, the EPB settings move to the cluster's EVIC display.
  NOTE:

  EPB fault light flashes continuously in service mode. Actuating the EPB switch in the apply position while also applying the brake pedal at the same time will remove the vehicle from service mode. Also the cluster will display text information on how to exit Service Mode if a scan tool is not available.

At any time, the EPB switch can be actuated. Depending on the speed of the vehicle when the EPB switch is actuated, the EPB module will output different commands under the following conditions:

Static Apply  (under 5 kph) - Actuates the EPB motors attached to the rear calipers.

Dynamic Apply  (over 5 kph) - Actuates the hydraulic braking system.

EPB module fail-safes include that the EPB can be applied with ignition off, EPB cannot be released with ignition off or ignition accessory, brake pedal must be applied when releasing the EPB.

Fig 1: Identifying Brake Warning And EPB Fault Lamp

Courtesy of CHRYSLER GROUP, LLC

EPB module illuminates the red BRAKE warning lamp when EPB is applied. EPB module faults are indicated through the amber EPB fault lamp and EVIC messages when present.