what should I do if my Ram 1500 DT (2019-Present) has a C121C code?

Learn how to diagnose and fix C121C ABS issues in Ram 1500 DT (2019-Present). Step-by-step guide with diagnostic procedures and repair instructions.

Solution

1. Preparation

• Gather necessary tools and safety equipment.
• Ensure the vehicle is parked on a level surface and secure it with wheel chocks.
• Disconnect the negative terminal of the battery to prevent electrical shorts.

2. Inspect and Clean ABS Wheel Speed Sensors

• Tools Required: Socket set, torque wrench, cleaning brush, isopropyl alcohol.
• Remove the wheel and tire assembly on each corner of the vehicle.
• Locate the ABS wheel speed sensor on each wheel hub.
• Unplug the sensor connector and remove the mounting bolt using a socket.
• Clean the sensor and mounting surface with isopropyl alcohol and a cleaning brush.
• Reinstall the sensor and torque the bolt to the manufacturer’s specification (typically around 15-20 ft-lbs).

3. Check ABS Control Module Connections

• Tools Required: Socket set, multimeter.
• Inspect the ABS control module connectors for corrosion or damage.
• Use a multimeter to test continuity and voltage at the ABS module pins.
• Repair or replace any damaged wiring or connectors as necessary.

4. Replace Faulty Wheel Speed Sensor (if necessary)

• If a wheel speed sensor is found to be faulty during testing, replace it.
• Tools Required: Socket set, torque wrench.
• Remove the old sensor as described in Step 2 and install a new OEM wheel speed sensor.
• Torque the mounting bolt to the manufacturer’s specification.

5. Reconnect Battery and Clear Codes

• Reconnect the negative terminal of the battery.
• Use the OBD-II scanner to clear the C121C code and any other related codes.
• Start the vehicle and perform a test drive to ensure the ABS and traction control systems are functioning properly.