Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
Pinpoint Test Y: Vacuum Sensor Faults
- Refer to Horn/Cigar Lighter
for schematic and connector information.
Normal Operation and Fault Conditions
The brake booster vacuum sensor receives a sensor supply voltage of 5 volts from the ABS module. The sensor is also grounded through the ABS module. The sensor uses the pressure differential between the atmosphere and the brake booster vacuum chamber to produce a return voltage signal to the ABS module between 0.2 volt and 4.9 volts. The ABS module uses other sensor inputs such as wheel speed, brake pedal and stability sensors to determine if the vehicle is stopping and at what rate of deceleration. This information is compared against the vacuum pressure sensor to determine the validity of the sensor signal and the working condition of the sensor itself.
DTC Fault Trigger Conditions
DTC Description Fault Trigger Condition ABS C0047:01 Brake Booster Pressure Sensor: General Electrical Failure Sets when the ABS module detects Line Failure. ABS C0047:62 Brake Booster Pressure Sensor: Signal Compare Failure This DTC sets when a pressure sensor reading that does not match what is expected compared to other sensor inputs. ABS C0047:1C Brake Booster Pressure Sensor: Circuit Voltage Out Of Range This DTC sets when a higher or lower than expected pressure sensor voltage which is detected. ABS C0047:64 Brake Booster Pressure Sensor: Signal Plausibility Failure This DTC sets when a pressure sensor reading does not match what is read from other ABS module sensors. Possible Sources
- Wiring, terminals or connectors
- Brake booster vacuum leak
- Brake booster vacuum sensor
- Brake booster
- ABS module
Visual Inspection and Pre-checks
- Inspect the brake booster for vacuum leaks.
- Inspect the brake booster for any obvious signs of damage.
- Inspect the brake booster vacuum sensor harness and connector of any obvious signs of damage.
- Make sure the brake booster vacuum sensor electrical connector is free from any corrosion or other contaminants.
NOTE: Use the correct probe adapter(s) when making measurements. Failure to use the correct probe adapter(s) may cause damage to the connector. - Y1 VERIFY ALL WIRING CONNECTIONS
- Ignition OFF.
- Disconnect ABS module connector C135 .
- Disconnect Brake Booster Vacuum Sensor connector C149A.
- Using a good light source, inspect each connector terminal for any corrosion.
- Inspect both connectors for any pushed-out pins. Refer to Connector Repair Procedures for schematic and connector information.
- Using a suitable mating terminal, check each female terminal for deformed or enlarged contacts by comparing the mating terminal's fit between each of the following pins:
- C135-44
- C135-27
- C135-17
- C149A-1
- C149A-2
- C149A-3
Are both connectors free of corrosion, pushed-out pins and deformed or enlarged contacts?
Yes GO to Y2 No REPAIR the terminals in question. - Y2 VERIFY THE ABS (ANTI-LOCK BRAKE SYSTEM) MODULE DTC (DIAGNOSTIC TROUBLE CODE) S
- Connect ABS module connector C135. Make sure the connector seats and latches correctly.
- Connect Brake Booster Vacuum Sensor connector C149A. Make sure the connector seats and latches correctly.
- Ignition ON.
- Clear the ABS DTCs.
- Ignition OFF.
- Ignition ON.
- Carry out the ABS self-test.
Are any DTCs from the DTC Fault Trigger Conditions Table present?
Yes GO to Y3 No GO to Y4 - Y3 CHECK THE BRAKE BOOSTER AND VACUUM HOSES FOR LEAKS
- Inspect the vacuum hoses, brake booster and brake booster seals for leaks or evidence of leaks.
Are the vacuum hoses, brake booster and brake booster seals free from leaks?
Yes GO to Y4 No REPAIR or INSTALL new components as necessary. - Y4 CHECK THE VACUUM SENSOR WIRING FOR A SHORT TO VOLTAGE
- Ignition OFF.
- Disconnect ABS module connector C135.
- Disconnect Brake Booster Vacuum Sensor connector C149A.
- Ignition ON.
- For ABS module connector: C135
- Measure the Voltage between:
Positive Lead Measurement / Action Negative Lead C135-44 Ground C135-27 Ground C135-17 Ground
Is any voltage present?
Yes REPAIR the circuit in question. No GO to Y5 - Y5 CHECK THE VACUUM SENSOR WIRING FOR A SHORT TO GROUND
- Ignition OFF.
- For ABS module connector: C135
- Measure the resistance between:
Positive Lead Measurement / Action Negative Lead C135-44 Ground C135-27 Ground C135-17 Ground
Are the resistances greater than 10, 000 ohms?
Yes GO to Y6 No REPAIR the circuit in question. - Y6 CHECK THE VACUUM SENSOR WIRING FOR AN OPEN
- For ABS module connector: C135
- Measure the resistance between:
Positive Lead Measurement / Action Negative Lead C135-44 C149A-1 C135-27 C149A-2 C135-17 C149A-3
Are the resistances less than 3 ohms?
Yes GO to Y7 No REPAIR the circuit in question. - Y7 CHECK THE VACUUM SENSOR WIRING FOR A SHORT TOGETHER
- For Brake Booster Vacuum Sensor connector: C149A
- Measure the resistance between:
Positive Lead Measurement / Action Negative Lead C149A-1 C149A-2 C149A-1 C149A-3 C149A-2 C149A-3
Are the resistances greater than 10, 000 ohms?
Yes GO to Y8 No REPAIR the circuits in question. - Y8 CHECK THE MODULE OUTPUT
- Connect ABS module connector C135. Make sure the connector seats and latches correctly.
- Ignition ON.
- For Brake Booster Vacuum Sensor connector: C149A
Is the voltage approximately 4.7 volts?
Yes INSTALL a new brake booster vacuum sensor. REFER to: Brake Booster . No GO to Y9 - Y9 VERIFY ALL WIRING CONNECTIONS
- Ignition OFF.
- Disconnect ABS module connector C135.
- Using a good light source, inspect all disconnected electrical connectors for the following:
- Corrosion - install new connector or terminal and clean the module pins.
- Damaged or bent pins - install new terminals or pins.
- Pushed-out pins - install new pins as necessary.
- Spread terminals - install new terminals as necessary.
Are the connectors free of corrosion, damaged pins, bent pins, pushed-out pins and spread terminals?
Yes GO to Y10 No REPAIR the connector or terminals. - Y10 CHECK FOR CORRECT ABS (ANTI-LOCK BRAKE SYSTEM) MODULE OPERATION
- Ignition OFF.
- Connect Brake Booster Vacuum Sensor connector C149A. Make sure the connector seats and latches correctly.
- Connect ABS module connector C135. Make sure the connector seats and latches correctly.
- Operate the system and determine if the concern is still present.
Is the concern still present?
Yes CHECK OASIS for any applicable service articles: TSB, GSB, SSM or FSA. If a service article exists for this concern, DISCONTINUE this test and FOLLOW the service article instructions. If no service articles address this concern, INSTALL a new ABS module. REFER to: Anti-Lock Brake System (ABS) Module . No REPAIR the connector or terminals.
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.
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