C1173 — Park Brake Switch # 1 Released Circuit Short to Gnd
**Introduction**
The diagnostic trouble code (DTC) C1173 indicates a problem within the **parking brake system**, specifically relating to the switch that signals whether the parking brake is engaged or released. This code suggests that there is a **short circuit to ground** in the circuit associated with the *Park Brake Switch # 1*.
It’s important to note that **labels and terminology** may vary depending on the vehicle manufacturer; some brands may refer to this component differently, but the underlying electrical fault remains similar.
### Fast Facts
- System affected: Parking Brake / Electronic Parking Brake (EPB) system
- Severity: Moderate (can affect safety systems or vehicle management)
- Main symptoms: Brake warning light, audible alert, or dashboard indicator
- Driveability: Limited — vehicle may still operate but with warnings or system restrictions
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Manufacturer variations for trouble code C1173
Different vehicle manufacturers may assign different labels or codes for similar faults related to the parking brake switch circuit. While the code C1173 is standard in the OBD-II system, some OEMs may use specific descriptions or different formats.
**Known label variations include:**
- Honda / Acura: CBA-134 “Parking Brake Switch Circuit Short”
- Ford: U0073 “Control Module Communication Bus ‘A’ Offline” (related to parking brake switch wiring issues in some models)
- Volkswagen / Audi: 00933 “Brake Pedal Switch – Circuit Short to Ground”
- BMW: 5E4C “Brake Switch Signal Circuit Short”
*(Always refer to the specific vehicle’s repair manual for exact labels and descriptions.)*
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What does trouble code C1173 mean?
In simple terms, C1173 points to a problem in the **circuit that transmits the parking brake status** to the vehicle’s Electronic Control Unit (ECU). The ECU constantly monitors the **parking brake switch**, which tells it whether the parking brake is engaged or released.
This code is triggered when the **ECU detects a persistent short to ground** in this circuit—meaning that somewhere in the wiring or the switch itself, there’s an unintended direct connection to the vehicle’s chassis or earth point, creating a **short circuit**.
Normally, the parking brake switch should have a defined resistance and signal voltage. When a short occurs, the ECU perceives this as a fault, and the code is stored.
**Typical contexts** where this code may appear include after a warning light activates during driving, or during vehicle diagnostics when checking emission or safety-related systems.
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Severity and risks of trouble code C1173
While C1173 isn’t usually a threat to the immediate operability of the vehicle, it has notable implications:
– **Potential safety issues** if the parking brake warning system doesn’t function correctly.
– **Malfunction of safety alerts**, which might lead to ignoring actual parking brake engagement.
– **Impact on other vehicle systems**, such as transmission or electronic stability systems, if they rely on parking brake status.
– **Possible false engagement or disengagement signals**, causing confusion or improper system responses.
**Can the vehicle be driven?**
Yes — but with constraints. The vehicle can typically be driven, but it’s advisable to address the fault promptly to ensure safety and proper system operation.
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Symptoms of trouble code C1173
Often, drivers or technicians might notice symptoms associated with this fault, which include:
– **Warning lights on the dashboard** related to the parking brake or safety systems.
– An **inoperative or incorrectly functioning parking brake system** alert.
– **Unusual messages or markings** on the instrument cluster, such as “Parking Brake Malfunction” or “Brake System Error.”
– **Audible chimes** that activate when the vehicle is started or during driving.
– **Inconsistent parking brake operation**, such as the system falsely indicating it is engaged or released.
In many cases, these symptoms are subtle, prompting inspection or code reading.
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Most likely causes of trouble code C1173
This fault is attributable to several potential issues, but some causes are more common than others. Here’s an overview:
1. **Damaged or corroded wiring or connector** within the parking brake switch circuit — often caused by moisture ingress or wear over time.
2. **Short circuit to ground** in the wiring harness — due to insulation damage, pinched wires, or connector pins bridging to ground.
3. **Faulty parking brake switch** itself — a switch that has internally failed or developed an electrical short.
4. **Incorrect or loose wiring connections** — especially after recent repairs or system modifications.
5. **Electronic control module (ECU) or body control module (BCM) malfunction** — though less common, a fault in the vehicle’s control modules can also cause false readings.
6. **Software issues or updates needed** — in some cases, a calibrate or software update may be necessary.
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How to diagnose trouble code C1173
Diagnosing this fault requires a systematic approach to confirm the cause and verify the circuit integrity.
**Recommended diagnostic steps include:**
1. **Visual Inspection:**
– Check the wiring harness connected to the parking brake switch for damage, wear, or corrosion.
– Inspect connector pins for looseness, corrosion, or misalignment.
2. **Test the parking brake switch:**
– Use a multimeter to verify the switch’s operation in both engaged and released states.
– Ensure the switch doesn’t show a persistent ground or open circuit when tested.
3. **Check wiring continuity:**
– Perform a continuity test on the circuit from the switch to the ECU connector.
– Confirm there are no shorts to ground or other wiring issues.
4. **Monitor live data:**
– Using a compatible scan tool, access live sensor data to see if the parking brake signal varies appropriately with manual engagement.
5. **Check for other codes:**
– Sometimes, related or auxiliary codes can provide clues on systemic issues.
6. **Inspect vehicle grounding points:**
– Confirm the ground connections are clean, tight, and free of corrosion to prevent false short signals.
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Possible repairs for trouble code C1173
Addressing this fault involves repairing or replacing faulty components and restoring circuit integrity. Common repairs include:
– **Repairing or replacing damaged wiring or connectors**:
– Basic repair requiring basic tools, or professional if wiring harness replacement is necessary.
– **Replacing the parking brake switch**:
– Usually requires some disassembly; a technician with appropriate tools can perform this task.
– **Correcting wiring faults or clearing shorts**:
– Involves locating the exact short circuit and repairing insulation or replacing damaged wires.
– **Cleaning and securing ground connections**:
– Simple but crucial to ensure effective grounding.
– **Firmware update or system reset**:
– Performed via dealership or specialised workshop, often requiring professional equipment.
It’s critical to identify the root cause, as merely clearing the code without fixing underlying issues will likely result in recurrence.
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Vehicles commonly associated with trouble code C1173 in Europe
This fault may present in various vehicle brands, especially those equipped with electronic parking brake systems (EPB).
**Common brands affected include:**
– **Volkswagen Group** (Volkswagen, Audi, Škoda, SEAT) — related to their electronic parking brake modules.
– **BMW / Mini** — where early models integrated parking brake switches into the electronic control systems.
– **Mercedes-Benz** — especially models with electronic parking brake functions.
– **Ford** — vehicles with electronic parking brake systems or switch wiring issues.
– **Honda / Acura** — models with electric parking brake switches.
**Note:** The specific occurrence depends heavily on the vehicle’s age, model, and system design.
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Frequent mistakes with trouble code C1173
Diagnosticians often make some common mistakes that can impede proper repair:
– **Assuming the fault is only in the switch** without inspecting the wiring or connectors.
– **Replacing the switch without verifying circuit integrity**, leading to recurring faults.
– **Ignoring grounding issues**, which can mimic switch faults.
– **Overlooking related codes** that may point to broader control module problems.
– **Not performing a thorough visual inspection**—missing corrosion, damage, or improper repairs.
– **Clearing the code prematurely** without fixing the cause, causing rapid reappearance.
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FAQ — trouble code C1173
**Can this code disappear on its own?**
It’s unlikely. This fault is typically persistent until the underlying wiring or component issue is addressed.
**Can I keep driving?**
In most cases, yes — but only temporarily. The vehicle’s parking brake warning might stay active, and safety systems could be affected. It’s recommended to have a professional diagnosis and repair soon.
**Why does the code return after clearing?**
The root cause—such as a short circuit or faulty switch—remains unresolved. When the system is reset, the ECU re-detects the fault during its next testing cycle.
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This comprehensive overview provides a practical, structured approach for understanding, diagnosing, and repairing the C1173 trouble code related to the parking brake switch circuit short to ground. Proper diagnosis and repair are essential to ensure vehicle safety and optimal system performance.