Brake System

Component Location





General Description

The HECU supplies operating voltage with pressure sensor in master cylinder & lateral G sensor. The HECU monitors supply voltage of each sensor for normal ESC control. If supply voltage is out of specified range ESC warning lamps are turned on and ESC controls are inhibited.

DTC Description

A failure is detected if the external sensor supply voltage is out of the specified range for more than the specified min. fault duration.

DTC Detecting Condition





Terminal and Connector Inspection

1. Many malfunctions in the electrical system are caused by poor harness(es) and terminal conditions. Faults can also be caused by interference from other electrical systems, and mechanical or chemical damage.
2. Thoroughly check connectors for looseness, poor connection, bending, corrosion, contamination, deterioration, or damage.
3. Has a problem been found?
YES
> Repair as necessary and then go to "Verification Of Vehicle Repair" procedure.
NO
> Go to "Power Circuit Inspection" procedure.

Power Circuit Inspection

1. Ignition "ON" & Engine "OFF".
2. Measure voltage between terminal "3" of the Yaw Rate & Lateral G sensor harness connector and chassis ground.

Specification : Approx. 5 V





3. Is the measured voltage within specifications?
YES
> Go to number 4 (Power Circuit Inspection procedure of pressure sensor).
NO
> Check for short to GND or short to B+ in the Yaw Rate & Lateral G sensor harness between terminal "3" of the Yaw Rate & Lateral G sensor harness connector and terminal "36" of the HECU harness connector. Repair as necessary and then go to "Verification Of Vehicle Repair" procedure. If OK, go to "Component Inspection" procedure.
4. Measure voltage between terminal "2" of the pressure sensor harness connector and chassis ground.

Specification : Approx. 5 V





5. Is the measured voltage within specifications?
YES
> Go to "Component Inspection" procedure.
NO
> Check for short to GND or short to B+ in the pressure sensor harness between terminal "2" of the pressure sensor harness connector and terminal "37" of the HECU harness connector. Repair as necessary and then go to "Verification Of Vehicle Repair" procedure. If OK, go to "Component Inspection" procedure.

Component Inspection

1. Ignition "OFF".
2. Engine "ON".
3. Does warning lamp remain On?
YES
> Substitute with a known-good HECU and check for proper operation. If problem is corrected, replace HECU and then go to "Verification Of Vehicle Repair" procedure.
NO
> Fault is intermittent caused by faulty HECU or was repaired and HECU memory was not cleared. Go to the applicable troubleshooting procedure.

Verification Of Vehicle Repair

After a repair, it is essential to verify that the fault has been corrected.
1. Connect scantool and select "Diagnostic Trouble Codes (DTCs)" mode.
2. Using a scantool, Clear DTC.
3. Operate the vehicle within DTC Detecting Condition in General Information.
4. Are any DTCs present ?
YES
> Go to the applicable troubleshooting procedure.
NO
> System performing to specification at this time.