Traction Control Valve RF Circuit Short To Ground

SPECIAL NOTES: Although many resources and most generic code readers display the definition of manufacturer-specific OBD II code C1402 as “Traction Control Valve RF Circuit Short To Ground”, it should be noted that this definition is not in current use in the US domestic market.

For reasons that are mostly technical in nature, many manufacturers in the US market define code C1402 as “Malfunction in Front Speed Sensor LH Circuit”, which definition describes a fault in a system that directly affects three safety-critical systems- the affected systems being the ABS, Traction Control, and Stability Control systems.

Being a manufacturer-specific code, carmakers are largely free to assign their own definitions and descriptions to C1402, or any other code that does not have a “0” as the second character. Refer to the Related Codes section of this guide for some examples of definitions of code P1402 other than “Malfunction in Front Speed Sensor LH Circuit”.

Always refer to the manual for the application being worked on for detailed information on how code P1402 is defined for that particular application, which could be different from how it is defined for other applications in any given model range. END OF SPECIAL NOTES.

OBD II fault code C1402 is a manufacturer specific code that many manufacturers define as “Malfunction in Front Speed Sensor LH Circuit”, and which is set when the PCM (Powertrain Control Module), or other controller such as the ABS, Traction Control, and/or the Stability Control Module detects a malfunction in the circuit that monitors the wheel speed sensor of the left-hand front wheel.

When diagnosing code C1402, it is important to recognize that wheel speed sensors (both singly and collectively), supply the reference data for the extremely complex algorithms that control the ABS, Traction-, and Stability Control systems.

All three of these systems are safety-critical, and a malfunction in any wheel speed sensor’s control/monitoring circuit could result in the partial or complete loss of functionality in one or more of these systems, a circumstance that could have serious, if not fatal results for a vehicles’ occupants.

In terms of operating principles, a wheel speed sensor consists of two parts; a sensor, which could be either an “active” (Hall Effect), or a “passive” (magnetic) sensor, and a device called a “reluctor ring” (also sometimes referred to as a “tone ring”, or less often, a “toothed wheel”.

In a fully functioning system, both types of sensor generate a signal voltage when the “teeth” of the reluctor ring pass in front of the sensing element, with the gap between the teeth of the reluctor ring causing the signal voltage to reduce, or fall away. Thus, as the reluctor ring rotates, the signal voltage switches from high-to-low-to-high, which switching forms the basis upon which one or more control modules calculate the rate of rotation of each wheel.

In practice, the speed at which each wheel rotates is fed to the ABS control module via a dedicated circuit, to be shared with the Traction Control -, Stability Control -, and Powertrain Control modules via the CAN (Controller Area Network) bus system. At this point, it should be remembered that the ABS system is the foundation upon which both the Traction -, and Stability Control systems depend for their “operating instructions”.

Both systems share many of the ABS systems’ components, but it is the ABS system that supplies (via its control module) the selective braking forces to individual wheels to correct wheel spin during acceleration, as well as selective braking forces to individual wheels to force the vehicle into following the steering angle set by the steering angle sensor when a potentially dangerous situation is detected by the Stability Control system However, since all of the above functions depend on the actual, and accurate rate of rotation of each wheel being relayed to the relevant control modules, none of these functions may be available to t