C1604

Component Location







General Description

The HECU consists of an ECU (Electronic Control Unit ) and a HCU( Hydraulic Control Unit).
The HCU portion of the assembly contains a pump motor, solenoid valves, and accumulator.
Increase and decrease of hydraulic pressure is operated by electronic motor, according to a measured signal by wheel speed sensor.
The function of HCU is to increase, decrease or maintain the hydraulic pressure supplied to a wheel cylinder by operating return pump according to HECU control signal while ABS control is active.
The ECU monitors various sensor and switch inputs.
These inputs are used to make decisions regarding HCU component operation.


DTC Description

This trouble code is set when the solenoid valves or operating circuit are malfunctioning as well as the trouble of HECU. The HECU motors the operation of the valves by checking the drive circuit of the solenoid valves,and then sets this code when the unexpected drain voltage is detected, and also sets this code when the HECU module itself is out of order. For example, when the EEPROM data read by master processor is different from the data sent before, or when the master/slave processor detects abnormal operation in RAM, Status Register, Interrupt ,Timer, A/D converter, cycle time,the HECU sets this code.


DTC Detecting Condition








Terminal and Connector Inspection

1. Many malfunctions in the electrical system are caused by poor harness(es) and terminal condition. 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 "Component Inspection" procedure.


Component Inspection

1. Ignition "OFF".
2. Ignition "ON".
3. Connect scantool and select "Diagnostic Trouble Codes(DTCs)" mode
4. Using a scantool, Clear DTC.
5. Select "Diagnostic Trouble Codes(DTCs)" mode again.
6. Are any DTCs present ?
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 "Verification Of Vehicle Repair" 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.