Chassis, generic

C0205 Stop Lamp Switch Circuit

Check engine lightUsually off
EmissionsNot relevant
Drive cycleNot required
Limp modeNo

C0205 cannot be found in the accessible J2012 lists, in NHTSA bulletins or in maker indexes; its title is identical to that of C0136, and GM-designed brake modules such as that of the Saab 9-4X use C0161 for the brake switch input. The switch itself is a closing contact that passes battery voltage to the brake module and the stop lamps when the pedal is pressed, as Saab's 9-3 ESP data show. Saab's 9-5 ESP module supervises the line by feeding a small current into it that returns to ground through the stop lamp bulbs; an interruption there is stored as C2470. Bosch and Nissan Diesel patented a scheme with two pedal switches that must agree, counting repeated mismatches before declaring both failed. Dark or permanently lit stop lamps are the first hint.

Likely causes

Stop lamp switch misadjusted, worn or broken
Blown stop lamp bulbs or fuse interrupting the monitoring path
Broken wire or corroded connector at the pedal

Symptoms

  • Stop lamps stay off or stay on
  • Cruise control will not engage or does not switch off when braking
  • ABS/ESC warning lamp on

Repair estimate

DifficultyEasyDIY possible
Parts and labour€15–120
Time0.2–1 h

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

Parts involved

stop lamp switchabs control modulecruise control module

Related codes

C0136C0161C0040

References: saabwisonline.com, saabwisonline.com, saabwisonline.com, patents.google.com.