Pinpoint Test F: DTC C1288, C1730 or C2778
Anti-Lock Control - Three-Channel
Pinpoint Tests
Pinpoint Test F: DTC C1288, C1730 or C2778
Refer to Wiring Diagram Set 42, Vehicle Dynamic Systems for schematic and connector information. Diagrams By Number
Normal Operation
The brake pressure transducer is attached to the brake master cylinder and is hardwired to the ABS module. The transducer can be serviced separately from the master cylinder. The ABS module supplies reference voltage, ground, and signal return to the transducer.
- C1288 (Pressure Transducer Main / Primary Input Circuit Failure) - a continuous and on-demand DTC that sets when the ABS module detects a voltage less than .2 volt or greater than 4.8 volts from the voltage return circuit.
- C1730 (Reference Voltage Out of Range (+5V)) - a continuous and on-demand DTC that sets when the brake pressure transducer supply voltage is less than 0.5 volt for more than 30 ms.
- C2778 (Sensor Power Supply Failure) - a continuous and on-demand DTC that sets when the ABS module detects voltage that is less than 4.75V or greater than 5.25V.
This pinpoint test is intended to diagnose the following:
- Wiring, terminals or connectors
- Brake pressure transducer
- ABS module
PINPOINT TEST F: DTCs C1288, C1730 OR C2778
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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F1 CHECK FOR ABS MODULE ON-DEMAND DTCs
- Ignition ON.
- Using the scan tool, clear the DTCs.
- Ignition OFF.
- Ignition ON.
- Enter the following diagnostic mode on the scan tool: ABS Module Self-Test.
- Retrieve and record the DTCs.
- Did DTCs C1288, C1730 or C2778 return?
Yes
GO to F2.
No
If other DTCs are retrieved, REFER to the ABS Module DTC Chart - Three-Channel. If no DTCs are retrieved, the concern may have been caused by a loose connection. TEST the system for normal operation. Anti-Lock Control - Three-Channel
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F2 CHECK THE ABS MODULE OUTPUT TO THE BRAKE PRESSURE TRANSDUCER
- Ignition OFF.
- Disconnect: Brake Pressure Transducer C1025.
- Ignition ON.
- Measure the voltage between brake pressure transducer C1025-3, circuit LCA16 (GN), harness side and brake pressure transducer C1025-1, circuit RCA16 (BU/BN) harness side.
- Is the voltage between 4.75 and 5.25 volts?
Yes
The concern may have been caused by a loose connection. TEST the system for normal operation.
No
If the voltage is greater than 5.25 volts, GO to F3.
If the voltage is less than 4.75 volts, GO to F4.
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F3 CHECK THE BRAKE PRESSURE TRANSDUCER SUPPLY CIRCUIT FOR A SHORT TO VOLTAGE
- Ignition OFF.
- Disconnect: ABS Module C135.
- Ignition ON.
- Measure the voltage between brake pressure transducer C1025-3, circuit LCA16 (GN), harness side and ground.
- Is any voltage present?
Yes
GO to F7.
No
GO to F8.
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F4 CHECK THE BRAKE PRESSURE TRANSDUCER SUPPLY CIRCUIT FOR A SHORT TO GROUND
- Ignition OFF.
- Disconnect: ABS Module C135.
- Measure the resistance between ABS module C135-29, circuit LCA16 (GN), harness side and ground.
- Is the resistance greater than 10,000 ohms?
Yes
GO to F5.
No
REPAIR circuit LCA16 (GN). CLEAR the DTCs. REPEAT the self-test.
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F5 CHECK THE BRAKE PRESSURE TRANSDUCER SUPPLY CIRCUIT FOR AN OPEN
- Measure the resistance between ABS module C135-29, circuit LCA16 (GN), harness side and brake pressure transducer C1025-3, circuit LCA16 (GN), harness side.
- Is the resistances less than 5 ohms?
Yes
GO to F6.
No
REPAIR circuit LCA16 (GN) for an open circuit. CLEAR the DTCs. REPEAT the self-test.
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F6 CHECK THE BRAKE PRESSURE TRANSDUCER SENSE CIRCUIT FOR AN OPEN
- Ignition OFF.
- Disconnect: Trailer Brake Control (TBC) Module C1025.
- Measure the resistance between TBC module C135-33, circuit VCA13 (YE/BU), harness side and brake pressure transducer C151-2, circuit VCA13 (YE/BU), harness side.
- Is the resistance less than 5 ohms?
Yes
GO to F7.
No
REPAIR circuit VCA13 (YE/BU). CLEAR the DTCs. REPEAT the self-test.
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F7 CHECK THE BRAKE PRESSURE TRANSDUCER FOR A SHORT
- Measure the resistance between brake pressure transducer C1025, pin 1, component side and brake pressure transducer C1025, pin 3, component side while firmly pressing and holding the brake pedal.
- Is the resistance less than 5 ohms?
Yes
INSTALL a new pressure transducer. CLEAR the DTCs. REPEAT the self-test.
No
GO to F8.
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F8 CHECK FOR CORRECT ABS MODULE OPERATION
- Disconnect: ABS Module C135.
- Check the ABS module connector for:
- corrosion
- pushed-out pins
- spread terminals
- Connect the ABS module connector and make sure that it is seated 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 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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