P04779788AD | Genuine Mopar® Anti-Lock Brake System Module

1. Compatible Vehicles

• 2012–2014 Jeep Wrangler (JK) (2-Door: Sport, Sahara, Rubicon, Willys Wheeler)

• 2012–2014 Jeep Wrangler Unlimited (JK) (4-Door: Sport, Sahara, Rubicon)

2. Engine Options

• 3.6L Pentastar V6 Gasoline

1. What is it?

The module serves as the central electronic computer ("brain") for your Jeep's braking and chassis control systems. Mounted directly to the hydraulic brake valve block under the hood, it processes data from wheel speed sensors, steering angle sensors, and yaw/g-sensors to regulate hydraulic fluid pressure to individual wheels.

2. Safety & Off-Road Systems Controlled

This module governs the entire suite of dynamic safety features on the Jeep Wrangler:

• Anti-Lock Braking System (ABS): Prevents wheels from locking up during sudden emergency stops or hard braking on loose surfaces.

• Electronic Stability Control (ESC) & Traction Control: Detects skid or loss of traction and applies selective braking to individual wheels to maintain vehicle trajectory.

• Hill Start Assist (HSA) & Hill Descent Control (HDC): Holds line pressure on inclines to prevent rollback and manages controlled downhill speeds on off-road trails.

• Electronic Roll Mitigation (ERM): Anticipates potential vehicle rollover conditions and intervenes using wheel-specific braking.

1. Multiple Dashboard Warning Lights

The primary symptom of a failing electronic control module is an array of illuminated instrument cluster lights:

• ABS Warning Light: Solid yellow/orange ABS icon.

• Traction Control / ESC Light: Illuminated skidding car icon.

• Brake System Warning Light: Red brake indicator light.

• Information Center Alerts: Text alerts on the cluster such as "Service Anti-Lock Brake System" or "Service Electronic Stability Control".

2. Diagnostic Trouble Codes (DTCs)

Connecting a professional scan tool to the ABS module or PCM often pulls specific internal failure or power supply error codes:

• C2116: ABS Pump Motor Low Voltage (a widespread internal circuitry failure on Jeep JK ABS modules, even if battery voltage is normal).

• C2200: Anti-Lock Brake Module Internal / Internal Electronic Fault.

• U0121: Lost Communication With Anti-Lock Brake System (ABS) Control Module.

• C0031 / C0034 / C0037 / C003A: Wheel Speed Sensor circuit codes (frequently caused by bad solder joints inside the module falsely reading sensor open circuits).

3. Loss of Anti-Lock Braking & Stability Features

When the module shuts down due to internal error detection:

• Emergency Stopping: In emergency stops or hard braking on gravel/snow, the wheels will lock completely and skid.

• Off-Road & Safety Assists Disabled: Functions like Hill Start Assist (HSA), Hill Descent Control (HDC), Electronic Roll Mitigation (ERM), and Traction Control are completely deactivated.

4. Unintended or Absent ABS Pump Activation

• Continuous Pump Motor Running: In some internal failure cases, a shorted transistor forces the ABS pump motor to run continuously, depleting the vehicle battery overnight.

• Lack of Pump Power: The module fails to feed power to the hydraulic pump during hard stops, preventing the brake pressure modulation needed to prevent skidding.