Traction control (TC) allows the anti-lock brake system (ABS) to control wheel spin and improve traction. If there’s a fault in the input signal of the traction control, on-board diagnostics could log code P0856.
Diagnostic trouble code P0856 stands for “Traction Control Input Signal.” The code is set once the powertrain control module (PCM) or electronic brake control module (EBCM) detects a problem that could affect ABS operation.
When your vehicle loses traction, the TC system applies the brakes to limit wheel slip. The TC system is an extension of the ABS, which means they share many components.
A control module (typically the ABS module), ABS wheel speed sensors, and the ABS hydraulic control unit are important components of both systems. A typical hydraulic control unit consists of a series of solenoid valves and a pump motor that work together to modulate fluid pressure to the brakes.
The traction control is controlled by both the EBCM and the PCM. The electronic brake control module requests torque reduction by sending a serial data message to the control module.
Once the ECM or EBCM detects a problem that could affect ABS operation, it will trigger code P0856. The traction control system will also be disabled.
Note: The definition of code P0856 might be different depending on the vehicle manufacturer. Consult the appropriate repair manual or repair database for the exact code definition.
DTC P0856 is a generic trouble code that applies to vehicles equipped with an OBD-II system. However, keep in mind that the vehicle’s year, make, and model can affect the steps for diagnosing it.
To diagnose a P0856 code, you’re going to need more than a scan tool. You’ll also need specific tools and up-to-date technical information about your ride’s traction control system. If you’re not familiar with vehicle repair and diagnosis, it’s best to leave the job to a trusted mechanic.
Attempting to fix trouble codes can be tricky—and the P0856 code is no exception. It can even lead to more damage if done incorrectly. So if you’re not confident you can resolve it on your own, it’s best to have a certified mechanic clear it for you.
But if you think you have the tools, DIY skills, and automotive knowledge to get the job done on your own, you can resolve the issue yourself. Keep in mind that there’s no umbrella fix for all trouble codes. So you must have the right repair manual before getting started. You might want to check out guides like those from Chilton or an ALLDATA subscription for comprehensive vehicle-specific repair information.
Any information provided on this Website is for informational purposes only and is not intended to replace consultation with a professional mechanic. The accuracy and timeliness of the information may change from the time of publication.