🚨 Diagnostic Profile
- Vehicle/Equipment Make: GENERIC
- Technical Description: Brake Booster Temperature Sensor C Circuit High
This code is set by the Electronic Brake Control Module (EBCM) when it detects a voltage reading from the ‘Circuit C’ temperature sensor that exceeds the expected calibrated range, registering as a ‘High’ input. This sensor is typically integrated into the hydraulic brake booster/pump assembly to monitor the operating temperature of the motor and pump unit used for brake assist and stability control functions. A ‘High’ circuit reading usually indicates an open circuit, a short to a reference voltage, or a failed sensor resistor internal to the pump assembly. When this fault is detected, the EBCM may restrict or disable specific brake assist functions, traction control, or stability control to prevent damage to the hydraulic pump motor, often triggering a corresponding warning light on the dash cluster (such as a Brake, ABS, or StabiliTrak indicator).
🚨 Repair Difficulty Tier
- Difficulty Rating: Intermediate
This repair requires a capable scan tool to read live chassis data and clear EBCM-specific codes, as well as a digital multimeter to check circuit continuity and resistance values at the pump connector. While not as complex as an internal hydraulic repair, accessing the connector near the brake booster pump assembly requires careful handling to avoid introducing air into the brake lines or damaging connector pins.
🛠️ Resolution Steps
- Step 1: Preliminary Inspection
Locate the brake booster pump/hydraulic control unit (HCU), usually mounted near the firewall or in a dedicated chassis bay. Visually inspect the wiring harness and electrical connector for the pump assembly for signs of corrosion, melted insulation, chafing, or bent pins. Check for any contamination (moisture, road salt, oil) around the connector that could be causing a high resistance path. - Step 2: Diagnostic Verification
Connect a scan tool capable of reading chassis/ABS-specific modules and monitor live data for the temperature sensor circuit. Back-probe the appropriate pins at the pump connector with a digital multimeter to verify the reference voltage is present (typically 5V) and check for continuity to the EBCM ground. A reading stuck at or near reference voltage (open circuit) confirms a wiring or internal sensor fault rather than an intermittent issue. - Step 3: Resolution & Reset Process
If wiring is damaged, repair or replace the harness section leading to the pump assembly, ensuring proper sealing to prevent future corrosion. If the wiring and connector test within specification, the internal temperature sensor within the pump motor assembly has likely failed, requiring replacement of the brake booster pump/HCU unit. After repairs, clear the stored code with the scan tool and perform a bleed/initialization procedure if the hydraulic unit was disturbed, then verify no codes return after a test drive involving several brake applications.
📦 Parts, Labor, and Budget Estimates
- Required Components/Software: Brake booster pump/HCU connector pigtail or full pump assembly, dielectric grease, bi-directional scan tool with ABS/EBCM access
- Average Component Price: $150 – $650 USD (harness repair is low end; full pump/HCU replacement is high end)
- Estimated Labor Hours: 1.5 – 3.5 hours (additional time required if brake bleeding/bedding procedures are needed after HCU replacement)
- Total Estimated Budget: $300 – $900 USD depending on whether a wiring repair or full pump/HCU replacement is required