Pinpoint Test H: DTCs C109D, C109E and C109F
Anti-Lock Control
Pinpoint Tests
Pinpoint Test H: DTCs C109D, C109E and C109F
Refer to Wiring Diagram Set 42, 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 will command the hydraulic pump motor to activate on the next (and any subsequent) brake pedal application to assist with vehicle braking. The ABS module will continue to use the pump motor for braking assist as long as the low vacuum condition exists.
The 5-volt reference voltage is sent to the sensor along circuit LCA37 (YE/OG), sensor output returns to the ABS module along circuit VCA38 (BN/VT), and the sensor is grounded through the ABS module along circuit RCA37 (WH/BU).
- 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 will be set. Also, a failure of the vacuum sensor will cause DTC C109E to be set.
- DTC C109F (Vacuum Sensor Signal Fault) - The vacuum sensor has 2 ambient air pressure inlet ports. If these ports become restricted or clogged, DTC C109F will be set.
This pinpoint test is intended to diagnose the following:
- Wiring, terminals or connectors
- Vacuum sensor
- ABS module
PINPOINT TEST H: DTCs C109D, C109E AND C109F
NOTICE: Use the Flex Probe Kit for all test connections to prevent damage to the wiring terminals. Do not use standard multimeter probes.
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H1 CHECK THE ABS MODULE DTCs
- Review the DTCs recorded during Inspection and Verification.
- Was DTC C109D the only recorded DTC?
Yes
GO to H2.
No
If DTCs C109E and/or C109F were retrieved, GO to H5.
For all other DTCs, REFER to the ABS Module DTC Chart. Diagnostic Trouble Code Tests and Associated Procedures
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H2 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 5 minutes for DTC C109D to set.
- Allow the vehicle to idle for a minimum of 6 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 H3.
No
If DTCs C109E and/or C109F were retrieved, GO to H5.
For all other DTCs, REFER to the ABS Module DTC Chart. Diagnostic Trouble Code Tests and Associated Procedures
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H3 CHECK THE ENGINE VACUUM
- Carry out the Intake Manifold Vacuum Test, refer to Diagnosis and Testing in Engine. Intake Manifold Vacuum Test Testing and Inspection
- Does the vacuum gauge indicate normal vacuum?
Yes
GO to H4.
No
FOLLOW the diagnostic direction as laid out in Engine.
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H4 CHECK THE SYSTEM FOR A VACUUM LEAK
- Inspect the following items for correct installation, cracks, holes or other damage that could cause a vacuum leak:
- Vacuum hoses
- Vacuum hose connections
- Vacuum sensor seal
- Aspirator tube
- Aspirator tube seal
- Master cylinder-to-booster seal
- Vacuum booster
- Are the items in good condition and free from leaks?
Yes
The condition to set the DTC is not present at this time. CLEAR the DTC. ATTEMPT to recreate the fault by allowing the vehicle to remain overnight in a cold environment. REPEAT the self-test.
If the DTC returns, INSPECT the items listed while cold.
If all items check out OK, INSTALL a new vacuum sensor. REFER to Power Brake Assist. CLEAR the DTC. REPEAT the self-test.
No
REPAIR or INSTALL new as necessary. CLEAR the DTC. REPEAT the self-test.
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H5 CHECK THE BRAKE BOOSTER VACUUM SENSOR
- Inspect the vacuum sensor ambient air pressure inlet ports.
- Are both ports free of contamination, debris and/or foreign material?
Yes
GO to H6.
No
REPAIR or INSTALL a new vacuum sensor as necessary. REFER to Power Brake Assist. CLEAR the DTCs. REPEAT the self-test.
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H6 CHECK THE BRAKE BOOSTER VACUUM SENSOR CIRCUITS FOR A SHORT TO GROUND
- Disconnect: ABS Module C135 .
- Measure the resistance between ground and:
- brake booster vacuum sensor C149-1, circuit VCA38 (BN/VT), harness side.
- brake booster vacuum sensor C149-2, circuit RCA37 (WH/BU), harness side.
- brake booster vacuum sensor C149-3, circuit LCA37 (YE/OG), harness side.
- Is the resistance greater than 10,000 ohms?
Yes
GO to H7.
No
REPAIR the affected circuit(s). CLEAR the DTCs. REPEAT the self-test.
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H7 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 C149, harness side as indicated in the following chart:
- Are the resistances less than 5 ohms?
Yes
GO to H8.
No
REPAIR the affected circuit(s). CLEAR the DTCs. REPEAT the self-test.
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H8 CHECK THE BRAKE BOOSTER VACUUM SENSOR CIRCUITS FOR A SHORT TOGETHER
- Measure the resistance between:
- brake booster vacuum sensor C149-1, circuit VCA38 (BN/VT), harness side and brake booster vacuum sensor C149-2, circuit RCA37 (WH/BU), harness side.
- brake booster vacuum sensor C149-1, circuit VCA38 (BN/VT), harness side and brake booster vacuum sensor C149-3, circuit LCA37 (YE/OG), harness side.
- brake booster vacuum sensor C149-2, circuit RCA37 (WH/BU), harness side, and brake booster vacuum sensor C149-3, circuit LCA37 (YE/OG), harness side.
- Are the resistances greater than 10,000 ohms?
Yes
GO to H9.
No
REPAIR the affected circuit(s). CLEAR the DTCs. REPEAT the self-test.
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H9 CHECK THE ACTIVE BRAKE BOOSTER CIRCUITS FOR A SHORT TO VOLTAGE
- Ignition ON.
- Measure the voltage between ground and:
- brake booster vacuum sensor C149-1, circuit VCA38 (BN/VT), harness side.
- brake booster vacuum sensor C149-2, circuit RCA37 (WH/BU), harness side.
- brake booster vacuum sensor C149-3, 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 H10.
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H10 CHECK THE ABS MODULE CONNECTOR
- 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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