Module, Electric Park Brake (EPBM): Operation

WARNING: This page is about a different car, the 2020 Jeep Cherokee. However, it is still accessible from the selected car via links, so may be relevant.

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

NOTE:

Once the EPB is applied, it does not need 12 volts to maintain clamp load and cannot be manually released if voltage is lost.

Input to the EPB module for the ON/OFF action is received from the EPB manual switch and a Controller Area Network-Chassis (CAN-C) line from the Electronic Vehicle Information Center (EVIC), Uconnect®, 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 the EPB switch is pulled to request a dynamic apply, where hydraulic braking is actuated via ESC control.

Manual Release

EPB module will release the EPB when the EPB switch is pushed and the brake pedal is applied, seat belt is on with the ignition ON.

Auto Park Brake

NOTE:

This mode is shipped from the factory in "OFF" mode.

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® menu which commands the EPB module to apply the EPB.

Drive Away Release (DAR)

When in any drive gear, the EPB module will automatically release the EPB when throttle input and engine torque is detected.

Safe Hold

If the EPB module detects that the vehicle is not secure (transmission not in park, door open, and others) it will actuate the EPB. This is hard programmed into the module and is not able to be turned off.

Loss of Voltage

EPB module is not able to manually release EPB when voltage is lost.

External Apply

Other vehicle systems can request the EPB 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 Uconnect® (customer usable method) and through the Scan Tool.
NOTE:
EPB fault light flashes continuously in service mode. Actuating the EPB switch will remove the vehicle from service mode.

Hill Start Assist (HSA)

The HSA system is designed to maintain the level of brake pressure for a short period of time after the brake pedal is released so that the vehicle does not roll on a hill between releasing the brake pedal and applying the accelerator pedal. The following must be true for HSA to activate:
- The vehicle must be stopped with the brake applied
- The vehicle must be at a eight percent or greater incline (three percent for manual transmissions)
- Gear selection must match uphill direction (forward gear for uphill, reverse for backing uphill)
NOTE:
The HSA system does not operate on an automatic transmission vehicle in the neutral position.

Auto Hold

The auto hold feature is a function of the Anti-lock Brake System (ABS) module and Hydraulic Control Unit (HCU). Auto hold is a comfort feature that allows the driver to remove foot from the brake pedal once the vehicle has come to a stop. The vehicle will be held at a stop for calibrated time by hydraulic braking. After the calibrated time has elapsed, time the EPB will engage and continue to hold the vehicle at a stop. Once auto hold is released or cancelled, the brake release should be smooth and similar to Hill Start Assist (HSA).

CAUTION:

If the Electric Park Brake (EPB) switch is actuated with the caliper removed from the caliper bracket and still connected electrically, the EPB motor will fully extend causing damage to the caliper piston. Disconnect and isolate the negative battery cable. If equipped with an Intelligent Battery Sensor (IBS), disconnect the IBS connector first before disconnecting the negative battery cable.

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 km/h (3 mph) Actuates the EPB motors attached to the rear calipers.

Dynamic Apply over 5 km/h (3 mph) actuates the hydraulic braking system.

The EPB module fail-safe function includes the ability to be applied with ignition OFF, EPB cannot be released with ignition OFF, brake pedal must be applied and seat belt must be on when releasing the EPB.

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.