Pinpoint Test K: DTCs C109D, C109E and C109F
Anti-Lock Control - Non-Hybrid
Pinpoint Test K: DTCs C109D, C109E and C109F
Refer to Wiring Diagram Set 42 (Fusion/Milan/MKZ, Fusion Hybrid, Milan Hybrid, MKZ Hybrid), Vehicle Dynamic Systems for schematic and connector information. Diagrams By Number
Normal Operation
The vacuum sensor is used by the ABS module to determine if hydraulic pump intervention is necessary due to loss of vacuum. The ABS module sends a 5-volt reference voltage to the sensor, the sensor compares the pressure in the booster to the ambient air pressure in the engine compartment and sends a varying voltage back to the ABS module based on the difference between the pressures. Normally, the pressure in the booster is much lower than ambient air pressure, as the pressure in the booster gets higher (closer to matching ambient air pressure), the lower the voltage sent back to the ABS module becomes.
When the vacuum in the brake booster falls below a predetermined level, the ABS module commands the hydraulic pump motor to activate on the next (and any subsequent) brake pedal application to assist with vehicle braking. The ABS module continues to use the pump motor for braking assist as long as the low vacuum condition exists.
- DTC C109D (Low Vacuum Condition Detected) - This DTC is set when the optimized hydraulic brake system is activated and does not necessarily indicate a concern with the vacuum sensor, the related wiring or the ABS module. This DTC most likely indicates a vacuum concern in the brake booster, engine and any related vacuum hoses/tubes. High altitude locations with low ambient air temperatures can cause a low vacuum condition to exist in the booster until the engine compartment warms up.
- DTC C109E (Vacuum Sensor Circuit Fault) - If, during normal operation or the ABS module on-demand self test, the ABS module detects an open circuit, a short to voltage or a short to ground on the vacuum sensor circuits, DTC C109E sets. Also, a failure of the vacuum sensor causes DTC C109E to set.
- DTC C109F (Vacuum Sensor Signal Fault) - The vacuum sensor has 4 ambient air pressure inlet ports (2 on each side). If these ports become restricted or clogged, DTC C109F sets.
This pinpoint test is intended to diagnose the following:
- Wiring, terminals or connectors
- Vacuum sensor
- ABS module
PINPOINT TEST K: DTCs C109D, C109E AND C109F
NOTICE: Use the correct probe adapter(s) when making measurements. Failure to use the correct probe adapter(s) may damage the connector.
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K1 CHECK THE ABS MODULE DTCs
- Review the DTCs recorded during Inspection and Verification.
- Was DTC C109D the only recorded DTC?
Yes
GO to K2.
No
If DTC C109E and/or C109F was retrieved, GO to K6.
For all other DTCs, REFER to the ABS Module DTC Chart. ABS Module DTC Chart
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K2 CHECK DTC RETURNABILITY
- Using the scan tool, clear the ABS module DTCs.
- Ignition OFF.
- Disconnect the scan tool.
- Start the engine.
- NOTE: It may take up to 3 minutes for DTC C109D to set.
- Allow the vehicle to idle for a minimum of 4 minutes.
- Ignition OFF.
- Connect the scan tool.
- Ignition ON.
- Enter the following diagnostic mode on the scan tool: Self Test - ABS Module.
- Is DTC C109D the only vacuum sensor DTC present?
Yes
GO to K3.
No
If DTC C109E and/or C109F was retrieved, GO to K6.
For all other DTCs, REFER to the ABS Module DTC Chart. ABS Module DTC Chart
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K3 CHECK THE ENGINE VACUUM
- Carry out the Intake Manifold Vacuum Test, refer to Diagnosis and Testing in Engine System - General Information Testing and Inspection. Intake Manifold Vacuum Test
- Record the vacuum reading.
- Does the vacuum gauge indicate normal vacuum?
Yes
GO to K4.
No
FOLLOW the diagnostic direction as laid out in Engine System - General Information Testing and Inspection.
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K4 CHECK THE BRAKE BOOSTER
- Carry out the Brake Booster Component Test, refer to Diagnosis and Testing in Brake System - General Information Component Tests.
- Do the brake booster and check valve pass the component test?
Yes
GO to K5.
No
REPAIR or INSTALL new as necessary. CLEAR the DTC. REPEAT the self-test.
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K5 CHECK THE BRAKE BOOSTER VACUUM LEVEL PID
- Connect the scan tool.
- Start the engine.
- Enter the following diagnostic mode on the scan tool: DataLogger - ABS Module.
- Compare the recorded vacuum reading to the brake booster vacuum level PID.
- Does the PID match the recorded vacuum reading?
Yes
INSTALL a new ABS module. REFER to Anti-Lock Brake System (ABS) Module Service and Repair. TEST The system for normal operation.
No
INSTALL a new brake booster vacuum sensor. REFER to Power Brake Actuation Service and Repair.
CLEAR the DTCs. TEST the system for normal operation.
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K6 CHECK THE BRAKE BOOSTER VACUUM SENSOR
- Inspect the vacuum sensor ambient air pressure inlet ports.
- Are all 4 ports free of contamination and/or foreign material?
Yes
GO to K7.
No
REPAIR or INSTALL a new vacuum sensor as necessary. REFER to Power Brake Actuation Service and Repair. CLEAR the DTCs. REPEAT the self-test.
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K7 CHECK THE BRAKE BOOSTER VACUUM SENSOR CIRCUITS FOR A SHORT TO GROUND
- Ignition OFF.
- Disconnect: ABS Module C135.
- Disconnect: Brake Booster Vacuum Sensor C1603.
- Measure the resistance between ground and:
- brake booster vacuum sensor C1603-1, circuit VCA38 (BN/VT), harness side.
- brake booster vacuum sensor C1603-2, circuit RCA37 (WH/BU), harness side.
- brake booster vacuum sensor C1603-3, circuit LCA37 (YE/OG), harness side.
- Is the resistance greater than 10,000 ohms?
Yes
GO to K8.
No
REPAIR the affected circuit(s). CLEAR the DTCs. REPEAT the self-test.
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K8 CHECK THE BRAKE BOOSTER VACUUM SENSOR CIRCUITS FOR AN OPEN
- Measure the resistance between the ABS module C135, harness side and the brake booster vacuum sensor C1603, harness side as indicated in the following chart:
- Are the resistances less than 5 ohms?
Yes
GO to K9.
No
REPAIR the affected circuit(s). CLEAR the DTCs. REPEAT the self-test.
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K9 CHECK THE BRAKE BOOSTER VACUUM SENSOR CIRCUITS FOR A SHORT TOGETHER
- Measure the resistance between:
- brake booster vacuum sensor C1603-1, circuit VCA38 (BN/VT), harness side and brake booster vacuum sensor C1603-2, circuit RCA37 (WH/BU), harness side.
- brake booster vacuum sensor C1603-1, circuit VCA38 (BN/VT), harness side and brake booster vacuum sensor C1603-3, circuit LCA37 (YE/OG), harness side.
- brake booster vacuum sensor C1603-2, circuit RCA37 (WH/BU), harness side, and brake booster vacuum sensor C1603-3, circuit LCA37 (YE/OG), harness side.
- Are the resistances greater than 10,000 ohms?
Yes
GO to K10.
No
REPAIR the affected circuit(s). CLEAR the DTCs. REPEAT the self-test.
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K10 CHECK THE ACTIVE BRAKE BOOSTER CIRCUITS FOR A SHORT TO VOLTAGE
- Ignition ON.
- Measure the voltage between ground and:
- brake booster vacuum sensor C1603-1, circuit VCA38 (BN/VT), harness side.
- brake booster vacuum sensor C1603-2, circuit RCA37 (WH/BU), harness side.
- brake booster vacuum sensor C1603-3, circuit LCA37 (YE/OG), harness side.
- Is any voltage present?
Yes
REPAIR the affected circuit(s). CLEAR the DTCs. REPEAT the self-test.
No
GO to K11.
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K11 CHECK THE ABS MODULE CONNECTORS
- Check ABS module C135 for:
- corrosion.
- pushed-out pins.
- spread terminals.
- Connect: ABS Module C135.
- Make sure the connector seats correctly, then operate the system and verify the concern is still present.
- Is the concern still present?
Yes
INSTALL a new ABS module. REFER to Anti-Lock Brake System (ABS) Module Service and Repair. TEST the system for normal operation.
No
The system is operating correctly at this time. The concern may have been caused by a loose or corroded connector. CLEAR the DTCs. REPEAT the self-test.
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