The U0119 trouble code on your Jeep Grand Cherokee indicates a network communication fault: Lost Communication with Tire Pressure Monitor Module. This code specifically relates to the Controller Area Network (CAN bus) system that allows the PCM, TCM, and other control modules to communicate. The Grand Cherokee from 2014, 2015, 2016, 2017, 2018, 2019, 2020, 2021, 2022, 2023, 2024 uses an advanced multi-network CAN system that integrates the Selec-Terrain system and Quadra-Drive modules.

Common Symptoms

When U0119 codes set, you may notice multiple warning lights illuminated on the dashboard simultaneously. These can include the check engine light, 4WD warning, and ABS warning lights. The vehicle may experience communication failures between different control modules, causing certain features to become inoperative or default to safe modes.

The Selec-Terrain system may be locked in a single mode or display a warning message about system unavailable. The Quadra-Drive system may disable 4WD engagement entirely, limiting the vehicle to rear-wheel drive. Some models may experience no-start conditions if critical modules cannot communicate during startup.

Network Architecture Overview

The Jeep Grand Cherokee uses multiple CAN bus networks operating at different speeds. The high-speed CAN bus carries critical data between the engine control module, transmission control module, and ABS module. The medium-speed CAN bus handles less critical functions like climate control and instrument cluster data.

Network Communication

When a module loses communication with others on the CAN bus, it sets a U-code specific to the missing data. The code indicates which module is not receiving expected data from another module. This can be caused by failures in the transmitting module, the receiving module, or the CAN bus wiring between them.

Diagnostic Procedures

Begin diagnosis by retrieving all stored U-codes using a professional scan tool capable of full module communication. The scan tool should be able to communicate with all modules on the vehicle to identify which modules cannot talk to each other.

CAN Bus Testing

Test the CAN bus wiring for continuity, shorts to ground, and shorts to voltage. The CAN high and CAN low wires should show approximately 60 ohms termination resistance across the two lines when the battery is disconnected. Use an oscilloscope to examine the CAN bus signal waveform for noise, glitches, or flat-line conditions.

Inspect all module connectors for corrosion, damage, or loose pins. On the Grand Cherokee, modules are located throughout the vehicle including the engine compartment, interior cabin, and rear cargo area. Water intrusion through the rear liftgate can cause corrosion in the trailer tow module and related circuits.

Common Failure Points

The Body Control Module (BCM) on the Jeep Grand Cherokee is a common source of network communication issues. The BCM controls many interior functions and serves as a gateway for multiple bus networks. When the BCM fails or loses communication, multiple U-codes may appear simultaneously.

The instrument cluster can fail and cause loss of communication with the PCM, resulting in U-codes related to the ECM/PCM. The TCM can also fail, causing U-codes related to transmission communication.

Repair Strategies

Identify the root cause of the communication failure before replacing any modules. Network issues are often caused by wiring problems, connector issues, or module power/ground failures. Simply replacing modules will not resolve wiring or connector problems and may cause damage to replacement modules.

Repair any damaged wiring or connectors before replacing control modules. Verify proper power and ground at all modules before condemning them as faulty. Many network communication issues resolve after cleaning corroded connectors or repairing damaged wiring.

Prevention and Maintenance

Protect your Grand Cherokee's electrical system by keeping modules dry and connectors clean. Periodically inspect modules located in areas prone to moisture, such as the engine compartment and rear cargo area. Avoid pressure washing module connectors directly.

Maintain the battery and charging system in good condition, as voltage fluctuations can corrupt module memory and cause communication issues. When performing welding repairs on the vehicle, disconnect all modules and remove the battery before applying welding current.

Jeep Grand Cherokee Specific Information

The Selec-Terrain system relies heavily on network communication between multiple modules. When CAN bus issues occur, the system cannot receive data from the wheel speed sensors, steering angle sensor, and other inputs required for proper operation. This causes the system to default to a safe mode and illuminate warning lights.

Module Locations

Key modules on the Jeep Grand Cherokee include:

• PCM: Engine compartment, typically near the battery
• TCM: Located in the transmission bellhousing area
• BCM: Behind the instrument panel, left side
• ABS module: Engine compartment, near the brake master cylinder
• Front/rear differential controllers: Located near respective differentials on 4WD models

Torque Specifications

When replacing control modules:

• Always use proper mounting hardware and torque specifications
• Verify all electrical connectors are properly seated before tightening
• Do not overtighten module mounting screws as this can damage the module housing

Parts Recommendations

Use only Mopar control modules for your Jeep Grand Cherokee. Replacement modules require programming to match your vehicle's VIN, configuration, and options. Aftermarket or used modules may have incompatible software or pre-existing faults that cause repeated failures.