Chassis, generic

C0161 ABS/TCS Brake Switch Circuit

Check engine lightUsually off
EmissionsNot relevant
Drive cycleRequired
Limp modeNo

C0161 is outside the accessible J2012 tables but well documented at GM. Service data for the later Saab 9-5 and the 9-4X define it as an implausible ABS brake switch signal: the EBCM receives the pedal-applied message from the body module and compares it with brake pressure and vehicle motion. The 9-4X sets it after four starts to over 40 km/h without any switch change, or when the pedal reads applied for 360 s above 20 km/h with less than 15 bar; the 9-5 uses 122 s and 6.2 bar plus a check for more than 15 bar for 2 s with the pedal released. GM bulletin PIT5181A for 2012–2014 full-size trucks and SUVs links C0161 and C0277 to a loose terminal in connector X205. Hill start assist may be disabled; braking while accelerating can also set it.

Likely causes

Brake pedal position sensor or switch out of adjustment
Loose or backed-out terminal in the pedal sensor wiring (GM X205)
Brake applied while accelerating (left-foot braking)
Brake pressure sensor reading that contradicts the pedal signal

Symptoms

  • Service stability or traction message
  • Cruise control or brake lights may misbehave
  • Hill start assist unavailable

Repair estimate

DifficultyEasyDIY possible
Parts and labour€0–250
Time0.3–1.5 h

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

Parts involved

brake light switchabs control moduletcs control module

Related codes

C0136C0205C0131

References: saabwisonline.com, saabwisonline.com, static.nhtsa.gov, static.nhtsa.gov.