C1440
Pressure Transducer Input Circuit Failure
YES
C1440 (ABS only)
Pressure Transducer Input Circuit Failure
ABS Module
Go To Pinpoint Test P .
Normal Operation
The brake pressure switch provides an additional speed control deactivation if the brake pedal position (BPP) switch fails. When the brake pedal is pressed, 1700 kPa (246 psi) of brake fluid pressure in the brake master cylinder opens the brake pressure switch, removing B+ voltage to the speed control servo electric clutch.
Possible Causes
- circuit 10 (LG) open
- circuit 307 (BK/YE) open, short to power
- ABS module
- brake pressure switch
- speed control deactivator switch
PINPOINT TEST P: DTC C1440 (ABS ONLY) - PRESSURE TRANSDUCER SIGNAL FAULT
CAUTION: Use the flex probe kit for all test connections to prevent damage to the wiring terminals. Do not use standard multimeter probes.
Test Step
Result / Action to Take
P1 VERIFY THE DTC
- Connect the diagnostic tool.
- Key in ON position.
- Clear DTC C1440. Road test the vehicle. Repeat the self-test.
- Does DTC C1440 repeat?
Yes
GO to P2 .
No
The system is OK at this time.
P2 MONITOR THE BRAKE PRESSURE SWITCH PID FOR CLOSED POSITION
- Enter the following diagnostic mode on the diagnostic tool: ABS Module PID.
- Monitor the powertrain control module (PCM) brake pressure switch PID.
- With foot off the brake pedal, does the PID read closed?
Yes
GO to P3 .
No
GO to P4 .
P3 MONITOR THE BRAKE PRESSURE SWITCH PID FOR OPEN POSITION
- Enter the following diagnostic mode on the diagnostic tool: ABS Module PID.
- Monitor the PCM brake pressure switch PID.
- While pressing the brake pedal, does the PID read open?
Yes
GO to P9
No
GO to P7 .
P4 CHECK THE CIRCUIT 10 (LG/RD) FOR AN OPEN
- Key in OFF position.
- Disconnect: Speed Control Deactivator Switch C1025.
- Key in ON position.
- Measure the voltage between the brake pressure switch C1025-2, circuit 10 (LG/RD), harness side and ground.
- Is the voltage greater than 10 volts?
Yes
GO to P5 .
No
REPAIR the circuit. CLEAR the DTCs and REPEAT the self-test.
P5 CHECK THE BRAKE PRESSURE SWITCH
- Key in OFF position.
- Measure the resistance across the brake pressure switch pins, component side.
- Is the resistance less than 5 ohms?
Yes
GO to P6 .
No
INSTALL a new speed control deactivator switch. REFER to Section 310-03 . CLEAR the DTCs. REPEAT the self-test.
P6 CHECK CIRCUIT 307 (BK/YE) FOR AN OPEN
- Connect: Speed Control Deactivator Switch C1025.
- Disconnect: ABS Module C155.
- Measure the voltage between the ABS module C155-40, circuit 307 (BK/YE). harness side and ground.
- Is the voltage greater than 10 volts?
Yes
GO to P9
No
REPAIR the circuit. CLEAR the DTCs. REPEAT the self-test.
P7 CHECK CIRCUIT 307 (BK/YE) FOR A SHORT TO POWER
- Key in OFF position.
- Disconnect: Brake Pressure Switch C1025.
- Key in ON position.
- Measure the voltage between the ABS module C155-40, circuit 307 (BK/YE), harness side and ground.
- Is any voltage present?
Yes
REPAIR the circuit. CLEAR the DTCs. REPEAT the self-test.
No
GO to P8 .
P8 CHECK BRAKE PRESSURE SWITCH
- Start the engine.
- Measure the resistance between the brake pressure switch C1025 pin 1, component side and the brake pressure switch C1025 pin 2, component side while firmly pressing the brake pedal.
- Is the resistance greater than 10,000 ohms?
Yes
GO to P9 .
No
INSTALL a new speed control deactivator switch. REFER to Section 310-03 . CLEAR the DTCs. REPEAT the self-test.
P9 CHECK FOR CORRECT ABS MODULE OPERATION
- Disconnect all ABS connectors.
- Check for:
- corrosion
- pushed-out pins
- Connect all ABS connectors and make sure they seat correctly.
- 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 in this section. TEST the system for normal operation.
No
The system is operating correctly at this time. Concern may have been caused by a loose or corroded connector. CLEAR the DTCs. REPEAT the self-test.
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