system.
When severe wheel slippage is detected (as on snow-covered roads), the Winter Mode feature of All-Speed
Traction Control causes the transmission to up-shift to higher gears at lower speeds than normal. Once a
slippery launch condition is detected, the transmission will remain in Winter Mode for a minimum of three
minutes. After that, if the road is providing normal traction, the system returns to providing normal up-shifts.
ELECTRONIC VARIABLE BRAKE PROPORTIONING
Upon entry into EVBP the inlet valve for the rear brake circuit is switched ON so that the fluid supply from the
master cylinder is shut off. In order to decrease the rear brake pressure, the outlet valve for the rear brake circuit
is pulsed. This allows fluid to enter the Low Pressure Accumulator (LPA) in the Hydraulic Control Unit (HCU)
resulting in a drop in fluid pressure to the rear brakes. In order to increase the rear brake pressure, the outlet
valve is switched off and the inlet valve is pulsed. This increases the pressure to the rear brakes. This back-and-
forth process will continue until the required slip difference is obtained. At the end of EVBP braking (brakes
released) the fluid in the LPA drains back to the master cylinder by switching on the outlet valve and draining
through the inlet valve check valve. At the same time the inlet valve is switched on in case of another brake
application.
The EVBP will remain functional during many ABS fault modes. If both the red BRAKE and amber ABS
warning indicators are illuminated, the EVBP may not be functioning.
DIAGNOSIS AND TESTING
ANTILOCK BRAKING SYSTEM
The ABS brake system performs several self-tests every time the ignition switch is turned on and the vehicle is
driven. The ABM monitors the systems input and output circuits to verify the system is operating correctly. If
the on board diagnostic system senses that a circuit is malfunctioning the system will set a trouble code in its
memory.
STANDARD PROCEDURE
ABS BRAKE BLEEDING
ABS system bleeding requires conventional bleeding methods plus use of a 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, see PRESSURE BLEEDING - BASE BRAKES .
NOTE:
An audible noise may be heard during the self-test. This noise should be
considered normal.
NOTE:
The scan tool is used to diagnose the ABS system. For additional information
refer to the Electrical, Electronic Control Modules section.
2007 Dodge Nitro R/T
2007 BRAKES ABS Service Information - Nitro