ABS/TCS Brake Switch Circuit Malfunction (GM)
The C0161 code means the vehicle's onboard diagnostic system has detected: ABS/TCS Brake Switch Circuit Malfunction (GM). This is a serious severity code.
- Keep driving?
- Yes, but fix soon
- DIY difficulty
- moderate
- Estimated cost
- $100 - $600 (wheel-speed sensor or wiring most often; EBCM/pump work costs more)
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Common Symptoms
- ABS and/or traction control warning lights on
- ABS and stability assist may be disabled (base brakes still work)
- Possible false ABS activation at low speed with a failing wheel-speed sensor
Probable Causes (Ranked by Likelihood)
- Fault in the ABS/traction control component this code names (ABS/TCS Brake Switch Circuit Malfunction) High
- Damaged wiring or a corroded connector in that circuit - road-splash zones corrode connectors High
- Failed related sensor or actuator Moderate
- Control module fault Low
Common Fixes by Vehicle
What techs usually find when diagnosing C0161 on specific vehicles — tap your vehicle for the fix and the exact part:
2003-2014 Chevrolet Silverado/GMC Sierra easy DIY
C0161 (brake switch circuit) on GM trucks is the #1 cause of ABS and traction control lights. The fix is usually a $20 brake light switch on the pedal bracket. Symptoms: brake lights work intermittently, cruise control will not engage, and ABS light stays on. Swap the switch in 15 minutes -- twist-lock on most years -- and the codes often self-clear on the next drive cycle.
Labor: 15-20 min2000-2014 Chevrolet Tahoe/Suburban easy DIY
Tahoe/Suburban C0161 is the classic brake switch failure. GM brake switches develop internal contact wear by 80-100K miles. If brake lights flicker when you tap the pedal, the switch is definitely the problem. Delphi and AC Delco both make direct OEM replacements. Replace and clear codes. No programming or bleeding required.
Labor: 15-20 min2003-2009 Hummer H2 easy DIY
H2 C0161 is nearly always the brake light switch. Hummer owners report this code around 60-100K miles. The switch is on the brake pedal bracket under the dash. Swap it in 15 minutes. If the switch has already been replaced and C0161 returns, check the 4-pin connector for corrosion -- dielectric grease on the pins prevents re-occurrence.
Labor: 15-20 minFrequently Asked Questions
What does C0161 mean?
C0161 is a chassis code used primarily by GM vehicles: ABS/TCS Brake Switch Circuit Malfunction. It concerns the ABS/traction control system.
Can I keep driving with C0161?
Base brakes keep working, but assume ABS and stability control are offline until repaired - allow longer stopping distances and drive gently, especially in rain or snow. Repair promptly.
Is C0161 the same on every make?
The decimal C0xxx range is dominated by GM's assignments (Chevrolet, GMC, Buick, Cadillac). Other makes may use this ID differently - if your vehicle is not a GM product, verify the meaning in your make's service information.
Mechanics Guide Step-by-step diagnosis
Step-by-Step Diagnostic Procedure
-
Read the code with a GM-capable scan tool and note the symptom byte/subcode if shown.
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View live data for the named circuit (e.g. all four wheel speeds while rolling for wheel-speed codes).
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Inspect the circuit's wiring and connectors - chassis harnesses live in the splash zone and corrode first.
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Follow the GM pinpoint test for C0161 before replacing components.
Sources 1
This page is built from documented references. Verify against your own service info before repair work.
- SAE J2012Diagnostic Trouble Code Definitions (defines the generic OBD-II code ranges)
Commonly Affected Vehicles
- Chevrolet, GMC, Buick, Cadillac (GM chassis code range)
Related Codes
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