C1173
Park Brake Switch # 1 Released Circuit Short to Gnd
Chassis Chassis/Safety Brake System Electrical 🔴 Serious — Stop or limit driving
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What This Actually Means
In plain language — no jargon

The parking brake switch signal wire is shorted to ground, preventing the ECU from detecting when the brake is released. Think of it like a light switch that's stuck in the "on" position due to a broken wire touching the frame.

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Symptoms You May Notice
3 known symptoms for this code
Parking brake warning light stays illuminated
Transmission may not shift properly or remain in Park
Brake system warning messages on dashboard
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Embedded Systems Insight
What the ECU/ECM is actually computing

The ECU monitors the park brake switch circuit voltage. When the brake is released, it expects a high voltage signal; when engaged, it expects low voltage. A short to ground forces the signal to 0V continuously, blocking the ECU's ability to detect brake state changes.

Voltage & Parameter Thresholds

Parameter Normal Range Fault Condition
Park Brake Switch Voltage 5V when released, 0V when engaged Constant 0V or below 0.5V when brake released
Circuit Resistance >10kΩ open, <100Ω closed <500Ω indicating unwanted ground connection
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Diagnostic & DIY Fix Guide
Check these in order — from cheapest to most complex
1
Wiring harness inspection
Visually trace the park brake switch connector and wiring for damaged insulation, pinches, or corrosion causing a ground short.
2
Park brake switch connector
Disconnect and reconnect the switch connector firmly, cleaning corrosion from terminals with contact cleaner.
3
Park brake switch assembly
Replace the switch if resistance testing confirms internal short or if wiring repair does not resolve the fault.