What Does C1172 Mean?
The park brake switch #1 applied circuit has an electrical failure, meaning the ABS/traction control module cannot confirm whether the parking brake is engaged. This affects the electronic parking brake system and may cause the parking brake warning light to illuminate. The driver may notice the parking brake indicator staying on or off regardless of actual brake status, and the ABS or stability control system may be partially disabled.
Common Causes
35%
Faulty park brake switch #1 (internal open or short circuit)
30%
Damaged or corroded wiring in the park brake switch circuit
20%
Poor connector contact at the park brake switch or ABS module
15%
ABS/traction control module internal fault
Diagnostic Steps
1
Check for related parking brake or ABS codes (C1173, C1174, C1177) to determine if the issue is isolated to switch #1 or systemic.
2
Locate the park brake switch #1 on the parking brake lever or pedal assembly. Disconnect the connector and inspect for corrosion, bent pins, or moisture intrusion.
3
Using a multimeter, measure continuity across the switch with the parking brake applied — it should show closed circuit (near 0 ohms). With brake released, it should show open circuit (OL).
4
Backprobe the switch circuit at the ABS module connector. With the parking brake applied, verify battery voltage (or ground, depending on circuit design) is present at the module input pin.
5
Check wiring harness for chafing, opens, or shorts to ground between the switch and the ABS module. Wiggle-test the harness while monitoring the circuit with a multimeter.
Estimated Repair Cost
$50 - $350
Parts + labor, varies by vehicle and location
The park brake switch #1 applied circuit has an electrical failure, meaning the ABS/traction control module cannot confirm whether the parking brake is engaged. This affects the electronic parking brake system and may cause the parking brake warning light to illuminate. The driver may notice the par...
The most common cause of C1172 (Park Brake Switch # 1 Applied Circuit Failure) is: Faulty park brake switch #1 (internal open or short circuit)
Typical repair costs for C1172 range from $50 to $350, depending on the vehicle, location, and whether you do it yourself or go to a shop.
The mechanical parking brake likely still functions, but the ABS module cannot verify its status. ABS and stability control features may be degraded or disabled. Avoid steep inclines until repaired. The vehicle can be driven cautiously to a repair facility.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to C1172 to identify the root cause.
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Quick Info
Category
Chassis
System
ABS / Parking Brake System
Difficulty
Type
Manufacturer
Recommended Tools
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