intermittent conditions of brake

1. Intermittent conditions of brake description of symptom

1. Preliminary inspection

Perform the brake control system inspection.

Refer to "54.Brake Control 4A.Troubleshooting(ABS/ESC) diagnostic System Check - Brake Controls".

Check the following items.

There should be no malfunctions in the warning light and indicator light operation.
There should be no DTC input.
The scan tool data is within the range of normal operation values.
The applicable diagnosis for addressing the customer's complaint has been performed.

2. Visual inspection

Visually inspect the vehicle condition with the following in mind before installing, removing, disassembling, and inspecting the components.

Terminal connection status inspection
Inspection for aftermarket accessory power diverged from the EHCU
EHCU ground installation status inspection
Switch and sensor installation status inspection

3. Intermittent conditions

If an intermittent condition exists, inspect the installation status of the electronic equipment. Verify that any device that was additionally installed is not connected to the CAN communication circuit.

1) Wire harness and connector

Intermittent open or short circuits may be caused by vibrations in the wire harnesses and connectors due to fluctuations in engine torque, bumps in the road, etc. Therefore, perform the following inspections.

Shake the related connectors or wiring while monitoring the scan tool data.
Shake the related connectors or wiring and monitor component operation while turning the components ON and OFF using the scan tool.

If moving the wire harness or connector affects the data displayed or the component or system operation, inspect the wire harness and connector as necessary.

2) Power supply and ground of the components

Inspect the power supply circuits of the components.
Inspect the installation status of the grounds of the components.

3) Effects caused by temperature

A malfunction may occur in the specific temperature range.

If the intermittent condition is caused by the temperature, inspect the following items.

Effects caused by outside air temperature
Effects caused by heat from the engine
Effects caused by heat from the exhaust piping and road surface

4) Sensitive to electrical noise

Some electronic components and circuits are sensitive to electrical noise. If electrical noise is suspected, inspect the following items.

Inspect whether wire harnesses are placed too close to the injector, motors, generators, etc.
Inspect the installation status of aftermarket products that use wireless devices and motors.
Inspect the generator rectifier circuit.

5) Malfunction symptom reproduction

If the malfunction can be reproduced frequently, the cause may be identified and the repair verification made easy.

6) Scan tool snapshot

Snapshots can be recorded using the scan tool. The snapshot function can be set to be triggered manually or automatically when a DTC sets. It can record ECU data in chronological order and perform malfunction analysis by displaying the data individually or in combination.