🚨 Diagnostic Profile
- Vehicle/Equipment Make: GENERIC
- Technical Description: Brake Pressure Sensor C Circuit/Open
This code is a Chassis-specific diagnostic trouble code monitored by the Electronic Brake Control Module (EBCM) or the ABS/Hydraulic Control Unit. It indicates that the module has detected an open circuit, a short, or an out-of-range signal from the third brake pressure sensor (Sensor C) used within the hydraulic brake system. This sensor is critical for monitoring hydraulic pressure during ABS, traction control, and electronic stability control operations. When the circuit is interrupted or the sensor signal falls outside the expected voltage range, the EBCM will disable certain ABS and stability control functions to prevent erratic braking behavior, often triggering an ABS warning light and/or a stability control warning light on the dashboard.
🚨 Repair Difficulty Tier
- Difficulty Rating: Professional Only
This repair requires specialized diagnostic equipment capable of reading ABS/EBCM-specific live data, as well as a digital multimeter to test resistance and voltage within the hydraulic control unit’s wiring harness. Because brake pressure sensors are often integrated into the hydraulic control unit (HCU) itself, diagnosis and replacement can involve bleeding the brake hydraulic system afterward, which requires proper bleeding procedures and sometimes a scan tool capable of performing automated bleed sequences. Due to the safety-critical nature of brake system components, this is not recommended as a DIY repair.
🛠️ Resolution Steps
- Step 1: Preliminary Inspection
Begin by visually inspecting the wiring harness and electrical connectors leading to the hydraulic control unit (HCU) and brake pressure sensor assembly. Look for corrosion, chafed wires, loose connector pins, or signs of moisture intrusion near the HCU, which is typically mounted near the brake master cylinder or along the chassis firewall area. Confirm the vehicle’s brake fluid level and condition, as contaminated or low fluid can sometimes trigger pressure sensor irregularities. - Step 2: Diagnostic Verification
Connect a capable scan tool to access EBCM-specific live data and freeze frame information related to brake pressure sensor circuits. Compare reported sensor voltage output to the manufacturer’s specification at rest (ignition on, engine off) and during brake pedal application. Use a digital multimeter to verify continuity and resistance across the sensor circuit wiring, checking for opens, shorts to ground, or shorts to power. If voltage readings are erratic or flatlined despite pedal input, the sensor or its wiring circuit is likely at fault. - Step 3: Resolution & Reset Process
If wiring damage is found, repair or replace the affected harness section and secure connections with proper weatherproof connectors. If the sensor itself (or the hydraulic control unit housing the sensor) is confirmed faulty, replace the component following the manufacturer’s specified brake system bleeding procedure to remove air introduced during disassembly. After installation, clear the stored fault code using the scan tool and perform a full ABS/EBCM self-test or road test to confirm the stability control and ABS systems operate correctly without re-triggering the code.
📦 Parts, Labor, and Budget Estimates
- Required Components/Software: Brake pressure sensor assembly or hydraulic control unit (HCU), wiring harness repair kit/connectors, brake fluid, bi-directional scan tool capable of ABS bleed procedures
- Average Component Price: $85 – $450 USD (depending on whether only the sensor or full HCU assembly requires replacement)
- Estimated Labor Hours: 1.5 – 3.5 hours
- Total Estimated Budget: $250 – $750 USD