Pinpoint Test I: DTCs C116A, C1288 and C1440
Anti-Lock Control
Pinpoint Tests
Pinpoint Test I: DTCs C116A, C1288 and C1440
Refer to Wiring Diagram Set 42, Vehicle Dynamic Systems for schematic and connector information. Diagrams By Number
Normal Operation
The brake pressure transducer is integral to the Hydraulic Control Unit (HCU). The transducer sends a signal to the ABS module that varies in relation to the amount of pressure applied to the brake pedal. The more pressure that is applied, the greater the signal sent to the ABS module. If a new transducer is needed, then a new HCU must be installed.
When the brake pedal is pressed, the stoplamp switch (also known as the brake ON/OFF switch) closes and a voltage is sent to the PCM. The PCM then sends a message over the High Speed Controller Area Network (HS-CAN) to the ABS module indicating that the brake pedal has been pressed.
- DTC C1288 (Pressure Transducer Main/Primary Input Circuit Failure) - If the transducer is open, shorted to ground or shorted to voltage, DTC C1288 will be set.
- DTC C1440 (Pressure Transducer Main/Primary Signal Faulted) - The signal that the brake pressure transducer sends to the ABS module is checked against other inputs to the module and if it does not agree with those inputs, DTC C1440 is set.
- DTC C116A (ABS Brake Pressure Transducer/Brake Switch Mismatch) - During normal operation, the ABS module compares the stoplamp switch HS-CAN message to the HCU internal pressure transducer. If the stoplamp switch message does not match the HCU transducer, DTC C116A will be set.
This pinpoint test is intended to diagnose the following:
- Wiring, terminals or connectors
- HCU
- ABS module
PINPOINT TEST I: DTCs C116A, C1288 AND C1440
NOTICE: Use the Flex Probe Kit for all test connections to prevent damage to the wiring terminals. Do not use standard multi-meter probes.
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I1 MONITOR THE ABS MODULE BRAKE ON/OFF (BOO_ABS) PID
- Connect the scan tool.
- Ignition ON.
- Enter the following diagnostic mode on the scan tool: DataLogger - ABS Module .
- Press and release the brake pedal while monitoring the BOO_ABS PID.
- Does the PID display ON with the brake pedal applied and OFF with the brake pedal released?
Yes
GO to I3.
No
GO to I2.
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I2 MONITOR THE PCM BRAKE ON/OFF (BOO) PID
- Enter the following diagnostic mode on the scan tool: DataLogger - PCM .
- Press and release the brake pedal while monitoring the BOO PID.
- Does the PID display ON with the brake pedal applied and OFF with the brake pedal released?
Yes
REFER to Information Bus to continue diagnosis of the HS-CAN.
No
REFER to Lighting and Horns to continue diagnosis of the stoplamp switch.
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I3 MONITOR THE ABS MODULE BRAKE PRESSURE (BRAKPRESS) PID
- Enter the following diagnostic mode on the scan tool: DataLogger - ABS Module .
- Firmly press and release the brake pedal while monitoring the BRAKPRES PID.
- Does the PID increase with firm pressure on the brake pedal and then decrease with the brake pedal released?
Yes
The system is operating correctly at this time. RETURN the vehicle to the customer.
No
INSTALL a new HCU. REFER to Hydraulic Control Unit (HCU) Service and Repair.
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