Powertrain, generic · Vehicle speed, idle control and auxiliary inputs

P056B Cruise Control Decrease Distance Signal

Check engine lightUsually off
EmissionsNot relevant
Drive cycleNot required
Limp modeNo

Cruise control buttons are almost always a resistor ladder on one or two signal lines, each button giving its own voltage; the module reading it (GM and Saab from about 2010: the body module; FCA: steering column module or PCM) sends the button state to the engine module over CAN. CARB names cruise control as the example of an emission-neutral diagnosis – it is simply switched off – so GM lists all these codes as type C and Ford as non-MIL: no warning lamp, the engine runs normally. P056B exists only with adaptive cruise control: the button to decrease following distance is stuck or invalid; counterpart of P056A. FCA's switch reads the distance button over the same ladder as the others. No manufacturer document available to us uses this code.

Likely causes

Distance button stuck or faulty
Moisture or wear in the steering wheel switch
Contact resistance in clockspring or steering wheel connector
Body module or cruise module

Symptoms

  • Following distance cannot be decreased
  • Cruise control locked out
  • No check engine light, engine runs normally

Repair estimate

DifficultyMediumDIY possible
Parts and labour€40–450
Time0.5–2 h

Typical range across vehicles; the real cost depends on what the testing finds.

Parts involved

cruise control switchclockspringswitch wiringbody control module

Related codes

P056AP0570P0564P0575

References: law.cornell.edu, static.nhtsa.gov.