C0135 is a manufacturer-specific chassis/ABS diagnostic trouble code. Its exact definition can vary depending on the vehicle manufacturer, ABS system, and model year.
On applicable GM vehicles, C0135 indicates an ABS/TCS System Pressure Circuit Open condition. The electronic brake control module (EBCM) has detected an open or interrupted circuit associated with the ABS/TCS system pressure signal.
The fault does not automatically mean that the brake pressure sensor itself has failed. An open wire, damaged connector, poor terminal contact, missing reference voltage, sensor ground problem, or an internal sensor fault can produce the code.
C0135 Fault Code Description
C0135 = ABS/TCS System Pressure Circuit Open.
Code type: Manufacturer-specific Chassis/ABS code.
Primary system: ABS, Traction Control System (TCS), and brake-pressure monitoring.
The EBCM monitors pressure information as part of ABS and traction-control operation. If the pressure circuit is electrically open or the expected pressure signal is missing, C0135 may be stored.
What Does C0135 Mean?
C0135 means that the ABS/TCS control system has detected an open condition in the system pressure circuit.
An open circuit means that the expected electrical path is interrupted. The interruption may occur in the pressure sensor circuit, wiring harness, electrical connector, terminal, power or reference circuit, ground circuit, or related ABS component.
Because an open circuit can be caused by several different components, the sensor should not be replaced until the complete circuit has been tested.
C0135 Symptoms
- ABS warning light.
- Traction Control warning light.
- Stability Control warning light where equipped.
- Service ABS message.
- Service Traction System message where equipped.
- ABS functionality may be disabled.
- Traction control may be disabled.
- Vehicle stability functions may be disabled.
- Stored ABS/EBCM diagnostic trouble code.
The exact symptoms depend on the GM vehicle and ABS system configuration.
Common Causes of C0135
- Open pressure sensor circuit.
- Broken or damaged wiring.
- Loose electrical connector.
- Corroded connector terminals.
- Damaged sensor terminals.
- Poor terminal tension.
- Open reference-voltage circuit.
- Open sensor ground circuit.
- Faulty brake pressure sensor.
- Water intrusion into the connector.
- High resistance in the wiring.
- Internal EBCM fault.
How to Diagnose C0135
1. Scan the ABS/EBCM
Use a scan tool capable of communicating with the ABS/EBCM. Confirm C0135 and check for additional ABS, pressure-sensor, voltage, communication, or traction-control codes.
2. Check ABS Live Data
Monitor the available brake-pressure data. A missing, unavailable, or implausible pressure signal can support the diagnosis of an open circuit.
3. Inspect the Pressure Sensor Connector
Inspect the pressure sensor connector for corrosion, water intrusion, broken terminals, loose pins, damaged wiring, or poor terminal tension.
4. Check the Reference Voltage
Using the correct GM wiring diagram, identify the pressure sensor reference-voltage circuit. Verify that the reference voltage reaches the sensor according to the manufacturer's specifications.
5. Check Sensor Ground
Test the sensor ground circuit for an open circuit, excessive resistance, or poor electrical connection.
6. Test the Pressure Signal Circuit
Check continuity between the pressure sensor and EBCM where applicable. Inspect the signal wire for an open circuit, damaged insulation, excessive resistance, or intermittent connection.
Always use the correct connector pinout for the exact GM vehicle and ABS module.
7. Check the Pressure Sensor
If the wiring, reference voltage, ground, and connector all test correctly, the pressure sensor itself should be evaluated according to the manufacturer's specifications.
8. Check the EBCM
If the complete pressure circuit tests correctly but C0135 remains present, the EBCM may require further diagnosis.
Do not replace the EBCM simply because C0135 is stored.
C0135 Diagnostic Signal Flow
C0135 GM
On applicable GM vehicles, C0135 indicates an ABS/TCS System Pressure Circuit Open condition.
The EBCM may set the code when the expected pressure-circuit signal is missing because of an open wire, connector problem, sensor fault, reference-voltage problem, ground problem, or another interruption in the circuit.
The exact wiring, sensor configuration, and diagnostic procedure depend on the GM model, model year, and ABS system.
Is C0135 Serious?
C0135 should be diagnosed promptly because an ABS pressure-circuit fault can affect ABS, traction control, and vehicle stability functions.
The basic hydraulic braking system may continue to operate, but electronic braking assistance and stability functions may be unavailable while the fault is active.
Can I Drive With C0135?
Limited driving may be possible if the normal braking system works correctly and there is no brake-fluid leak or abnormal brake-pedal behavior.
However, ABS and traction-control functions may be disabled. The vehicle should be inspected and repaired as soon as possible.
C0135 Repair Cost
The repair cost depends on the actual cause of the open circuit.
- Diagnostic testing: approximately $50–$150+.
- Wiring repair: approximately $50–$300+.
- Connector or terminal repair: approximately $50–$250+.
- Pressure sensor replacement: approximately $100–$500+.
- EBCM-related repair or replacement: approximately $500–$1,500+.
These are general estimates only. Actual repair costs vary according to the GM vehicle, parts prices, labor rates, and failed component.
Common Repair Mistakes
Replacing the Sensor Without Testing the Wiring
An open wire or damaged connector can produce C0135 even when the pressure sensor is working correctly. Always test the complete circuit before replacing the sensor.
Ignoring Connector Damage
ABS connectors can develop corrosion, loose terminals, or water intrusion. A visual and electrical inspection should be performed before replacing expensive components.
Using the Wrong Wiring Diagram
GM ABS systems can use different pressure-sensor circuits and connector configurations. Always use the wiring diagram for the exact vehicle and ABS module.
Replacing the EBCM Too Early
An EBCM should not be condemned until the pressure sensor circuit, power, ground, wiring, and connectors have been tested.
Related Codes
- C0131 – ABS/TCS System Pressure Circuit Malfunction
- C0132 – ABS/TCS System Pressure Circuit Range/Performance
- C0133 – ABS/TCS System Pressure Circuit Low
- C0134 – ABS/TCS System Pressure Circuit High
- C0135 – ABS/TCS System Pressure Circuit Open
- C0136 – Base Brake System Pressure Circuit Malfunction
- C0137 – Base Brake System Pressure Circuit Range/Performance
- C0138 – Base Brake System Pressure Circuit Low
- C0139 – Base Brake System Pressure Circuit High
- C0140 – Base Brake System Pressure Circuit Open
FAQ About C0135
What does C0135 mean?
C0135 means ABS/TCS System Pressure Circuit Open on applicable GM systems. It indicates that the pressure circuit has an open or interrupted electrical path.
What causes C0135?
Possible causes include broken wiring, an open signal circuit, damaged connectors, poor terminals, an open reference or ground circuit, a faulty pressure sensor, or an EBCM problem.
What does C0135 mean on GM?
On applicable GM vehicles, C0135 indicates an ABS/TCS System Pressure Circuit Open condition. The exact diagnostic procedure depends on the GM vehicle and ABS system.
Does C0135 mean the pressure sensor is bad?
Not necessarily. An open wire, damaged connector, poor terminal contact, reference-voltage problem, or ground fault can also cause C0135.
Can I drive with C0135?
The vehicle may still have normal basic braking, but ABS and traction-control functions may be disabled. The problem should be diagnosed as soon as possible.
How do I fix C0135?
Start by scanning the ABS/EBCM, inspecting the pressure sensor connector, checking the reference voltage and ground, and testing the pressure signal circuit for continuity and excessive resistance. Repair the circuit or component that fails testing.
Final Result
C0135 is a manufacturer-specific chassis/ABS diagnostic trouble code. On applicable GM vehicles, it indicates an ABS/TCS System Pressure Circuit Open condition.
The most reliable diagnosis is to check the ABS/EBCM for additional codes, inspect the pressure sensor and connector, verify reference voltage and ground, and test the complete pressure signal circuit before replacing components.
Always confirm the exact C0135 definition, wiring, and diagnostic specifications for the specific GM vehicle and ABS system.