Code Definition

U121E — Lost Communication With Steering Wheel Cruise Control Switch

System: Network Communication  |  Type: Manufacturer-Specific  |  Make: Jeep

About U121E

U121E is a manufacturer-specific network communication diagnostic trouble code recorded for Jeep vehicles. It belongs to the U-prefix family of codes, which covers inter-module network communication (CAN, LIN, FlexRay, or similar) faults.

Scanning & clearing: Network (U) codes report communication faults between modules. When diagnosing U-codes, checking the vehicle's CAN bus integrity, supply/ground at each module, and reading all modules for related faults is usually the first step.

U121E is a manufacturer-specific code. The same code string on a different make may have a different meaning. Always confirm the code's definition against the vehicle's service information for the specific make and model under test.

Code Information

The Body Control Module or Powertrain Control Module receives the steering wheel cruise control switch inputs, which pass through the clock spring, also called the spiral cable, in the steering column. These switches let the driver set, resume, and cancel cruise control and adjust speed. DTC U121E sets when the controlling module loses valid communication or signal from the steering wheel cruise control switches for a calibrated period. Depending on the design the switches may report over a LIN or CAN link or through a resistive circuit read by a column module, and the clock spring carries the...

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