OneMoreVet

Had the car inspected yesterday. Plugged in computer no codes, passed with flying colors. On my drive home CEL came on. Went to Advance Auto to borrow code reader, found C0161 and P0056. Reset them twice but they came back. The inspection was by a friend so no monkey business.

P0056 is for the o2 sensor/heater. Easy enough to test but the C0161 Antilock Brake System (ABS)/Traction Control System (TCS) Brake Switch Circuit EBCM has me scratching my head. I've owned the car for over a year and never any CEL's. Anyone have an idea what's going on or where I should start?

Thanks

C6topless

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Here is the diagnostic procedure for that code:
DTC C0161 00:Antilock Brake System (ABS) Brake Switch/Sensor Circuit not Plausible.
Circuit/System Description
The brake pedal position (BPP) sensor is an input to the body control module (BCM). The BCM then sends a serial data message to the electronic brake control module (EBCM) and other electronic control modules. The BPP sensor is a potentiometer type sensor with a 5-volt reference circuit and a low reference circuit. The instrument panel module (IPM) supplies the 5-volt reference to the BPP.
Conditions for Running the DTC
• The ignition is ON.
• The vehicle speed is greater than 16 km/h (10 mph).
• The ignition voltage is greater than 9.5 volts.
Conditions for Setting the DTC
• The brake pedal is sensed as applied.
• The vehicle speed is greater than 40 km/h (25 mph).
• The vehicles acceleration exceeds 8 km/h per second (5 mph per second).
• Brake pedal is not applied.
• Master cylinder pressure is greater than 150 psi.
• The vehicle speed is greater than 24 km/h (14 mph).
• The vehicles deceleration exceeds 11.5 km/h per second (7 mph per second).
Action Taken When the DTC Sets
The ABS/TCS/ESC remains functional.
Conditions for Clearing the DTC
• The condition for the DTC is no longer present and the DTC is cleared with a scan tool.
• The EBCM automatically clears the history DTC when a current DTC is not detected in 100 consecutive drive cycles.
Diagnostic Aids
The DTC C0161 00 can be set if the vehicle has been driven with the brake applied during acceleration.
Circuit/System Verification
With the ignition ON, use a scan tool to display DTCs for the BCM.
⇒If DTC C0277 or C0278 are present, go to Diagnostic System Check - Vehicle.
⇒If no DTCs are present, go to Diagnostic Aids.
Repair Instructions
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

( courtesy of another forum member - old thread )

OneMoreVet

Thanks C6topless! I searched and found that too. I also read a bad ground or a flakey battery can be the cause. For the hell of it, I twisted the battery cables (very snug but the ground moved) and took it for a spin. I got a calibrating active handling and then another message. Took it to get codes read, the C0161 was gone.

Did load test on battery and found it weak so hopefully that's my problem. Looking back I had the active handling/traction control light come on twice when I took the car out of storage this year (Ctek battery tender) but it didn't come back.

I made an appointment with the Chevy service dept. yesterday morning which I'll be canceling for now. Good thing because Service dude scared the crap out of me.

Bill Curlee

He should at $100 an hour!