C1288

Anti-Lock Control

Pinpoint Test J: DTCs C1288, C1440 and C1446

Normal Operation

The brake pressure transducer is integral to the Hydraulic Control Unit (HCU). When the brake pedal is pressed, 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 needs to be installed, then a new HCU (Hydraulic Control Unit) must be installed.





This pinpoint test is intended to diagnose the following:

- Wiring, terminals or connectors

- HCU (Hydraulic Control Unit)

- ABS module

PINPOINT TEST J : DTCs C1288, C1440 AND C1446

J1 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.

- Press and release the brake pedal while monitoring the BOO_ABS PID.

Does the PID switch to ON with the brake pedal pressed and then to OFF with the brake pedal released?

Yes
GO to J3.

No
GO to J2.

J2 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 switch to ON with the brake pedal pressed and then to OFF with the brake pedal released?

Yes
REFER to Information Bus to continue diagnosis of the HS-CAN (High Speed Controller Area Network) bus.

No
REFER to Lighting and Horns to continue diagnosis of the stoplamp switch and stoplamps.

J3 MONITOR THE INITIAL (BRAKE PEDAL NOT APPLIED) BRAKE PRESSURE USING THE ABS MODULE BRAKE PRESSURE (BRAKPRESS) PID

- Enter the following diagnostic mode on the scan tool: DataLogger- ABS.

NOTE: It is normal for the brake pressure (BRAKPRES) PID to occasionally spike high due to the test pulse sent to the pressure sensor by the ABS module.

NOTE: Negative brake pressure is considered normal due to the signal is not calibrated.


- With the brake pedal not applied, record the pressure displayed by the BRAKPRES PID.

Is the initial brake pressure greater than -1551 kPa (-225) with the brake pedal not applied?

Yes
The condition is not present at this time. CLEAR the DTCs. CYCLE the ignition key. REPEAT the self-test.

No
INSTALL a new HCU (Hydraulic Control Unit). REFER to Hydraulic Control Unit (HCU) . REPEAT the self-test.