The largest online repair guide library for every car

About us
Contact support
FAQ
Sign up
Sign in

2019 Jeep Renegade ABS/Traction Control Light On & U0121 Code

0

Mike T. · rep 0 · May 25, 2:20 AM · 1 replies · solved · Question

Vehicle: 2019 Jeep Renegade Limited

Hey everyone,

My 2019 Jeep Renegade Limited (2.4L FWD) just lit up the ABS warning light and the Traction Control light on the dash. I also noticed the Cruise Control isn't working anymore. I scanned it with my OBD-II reader, and it pulled a U0121 code: "Lost Communication with Anti-Lock Brake System (ABS) Control Module."

This happened suddenly while I was driving. I haven't hit any major potholes or had any work done recently. Could this be a bad sensor, or something more serious with the ABS module itself? I'm concerned about driving it with these safety systems offline. Any common issues with the Renegade that cause this?

Thanks for any insights!

✓ Accepted solution

ClearTheCode Admin

ClearTheCode Team · rep 0 · May 25, 2:20 AM

0

ClearTheCode admin answer:

A U0121 code on your 2019 Jeep Renegade, indicating "Lost Communication with Anti-Lock Brake System (ABS) Control Module," is a significant diagnostic code. This means the engine control unit (ECU) or another module isn't receiving expected data from the ABS module. This will disable ABS, Traction Control, and often Cruise Control as a safety measure.

Common Causes for U0121:

  1. Faulty ABS Module: The ABS control module itself can fail internally, leading to a loss of communication.
  2. Wiring or Connector Issues: Damaged, corroded, or loose wiring and connectors to the ABS module are very common culprits. This includes power, ground, and CAN bus (communication) wires.
  3. Blown Fuse: A dedicated fuse for the ABS module might have blown, cutting off power.
  4. Wheel Speed Sensor (WSS) Issues: While a bad WSS typically throws a specific WSS code (e.g., C0031 for front left), a severe or intermittent WSS fault could, in rare cases, disrupt ABS module function enough to cause communication loss.
  5. CAN Bus Network Problem: The Controller Area Network (CAN bus) is how modules communicate. A fault anywhere on the CAN bus that impacts the ABS module's connection can cause this code.

Troubleshooting Steps:

  1. Check Fuses: Locate the fuse box (often under the hood and/or in the cabin) and check all fuses related to the ABS system. Consult your owner's manual for the exact fuse locations and ratings.
  2. Visual Inspection of Wiring: Inspect the wiring harness leading to the ABS module (usually located near the master cylinder in the engine bay). Look for any signs of fraying, rodent damage, corrosion, or loose connections.
  3. Battery Health: Ensure your battery is in good condition and terminals are clean and tight. Low voltage can sometimes cause communication issues.

When to See a Shop:

  • Immediately: Driving without functional ABS and Traction Control can compromise safety, especially in emergency braking or slippery conditions. It's best to have this addressed promptly.
  • Professional Diagnosis: Diagnosing a U0121 often requires advanced tools to check CAN bus integrity, power/ground at the ABS module, and potentially test the module itself. A qualified technician can accurately pinpoint if the issue is wiring, a fuse, or a faulty ABS module, which can be an expensive component to replace. They can also check for specific wheel speed sensor data that might indirectly point to the issue.
Menu

Help & account