Visual Inspection and Diagnostic Pre-checks
WARNING: This page is about a different car, the 2020 Ford F-150. However, it is still accessible from the selected car via links, so may be relevant.
- 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.
- C1: VERIFY ALL WIRING CONNECTIONS
- Ignition OFF.
- C2: VERIFY THE ABS MODULE DTCS
- C3: 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 No Go to C4. REPAIR or INSTALL new components as necessary.
- C4: CHECK THE VACUUM SENSOR WIRING FOR A SHORT TO VOLTAGE
- Ignition OFF.
- C5: CHECK THE VACUUM SENSOR WIRING FOR A SHORT TO GROUND
- Ignition OFF.
- Measure the resistance between:
- C6: CHECK THE VACUUM SENSOR WIRING FOR AN OPEN
- Measure the resistance between:
- C7: CHECK THE VACUUM SENSOR WIRING FOR A SHORT TOGETHER
- Measure the resistance between:
(+) Brake Booster Vacuum Sensor (C1799) Connector, Harness Side (-) Brake Booster Vacuum Sensor (C1799) Connector, Harness Side SRef - VCA38 (BROWN) - Pin 1 SIGRTN - RCA37 - Pin 2 SRef - VCA38 (BROWN) - Pin 1 VREF - LCA37 - Pin 3 SIGRTN - RCA37 (WHITE/BLUE) - Pin 2 VREF - LCA37 - Pin 3 VAC SNS P VAC SIG VAC SNS P VAC GND VAC SIG VAC GND - Are the resistances greater than 100, 000 ohms?
Yes No Go to C8. REPAIR the circuits in question.
- Measure the resistance between:
- C8: CHECK THE MODULE OUTPUT
- C9: VERIFY ALL WIRING CONNECTIONS
- Ignition OFF.
- C10: CHECK FOR CORRECT ABS MODULE OPERATION
- Ignition OFF.
- Brake Booster Vacuum Sensor connector connected. (C1799) Make sure the connector seats and latches correctly.