4.
Inspect opearating status of all vlaves with Actuation Test.
Specification : It's normal if operating sound is heard.
The HECU supplies battery power to all solenoid valves with a valve relay which is controlled by the Electronic Control UNIT(ECU). The valve relay and all solenoid valves are installed inside the HECU ( Hydraulic and Electronic Control Unit ).
The HECU monitors voltage of the valve relay to check if the HECU can perform ABS control normally. When the valve relay is switched to ON, the HECU will set this code if the solenoid drive voltage is below permissible voltage ranges for a period of time. When the valve relay is switched to OFF, the HECU sets this code if the solenoid drive voltage is over the permissible voltage range for a period of time.
Item | Detecting Condition | Possible cause | |
DTC Strategy | ● Voltage monitoring | ● Open or short in power supply circuit (IGN+) ● Inoperative HECU | |
Case 1 | Monitoring Period | ● Once during startup. | |
Enable Conditions | ● Watchdog and valve relay function is tested during startup.A failure is detected if the valve relay/Enable remains in off position when it is turned on and vice versa. Reason could be short to GND or UZ, interrupted lines or a inoperative output stage etc. | ||
Case 2 | Monitoring Period | ● Continuous | |
Enable Conditions | ● A Fault is detected if valve relay voltage ＜ 0.8 * battery voltage for a time 500 ms. | ||
Case 3 | Monitoring Period | ● Continuous | |
Enable Conditions | ● If valve relay malfunction and supply solenoid valve short to battery or supply solenoid valve and medium or high ohmic short of valve relay (or a valve) to valve relay voltage, solenoid valve voltage or GND are detected. | ||
Fail Safe | ● No valve actuation possible. ● The ABS/EBD/ESP functions are inhibited. ● The ABS/EBD/ESP warning lamps are activated. | ||
Connect scantool to Data Link Connector(DLC)
Ignition "ON" ＆ Engine "OFF".
Select the "Actuation Test" mode on the scantool.
Inspect opearating status of all vlaves with Actuation Test.
Specification : It's normal if operating sound is heard.
Do all valves operate normally?
▶ Fault is intermittent caused by poor connection in power harness (ABS2) and/or HECU's connector or wasrepaired and HECU memory was not cleared. Thoroughly check connectors for looseness, poor connection, bending, corrosion, contamination, deterioration, or damage. Repair or replace as necessary and then go to "Verification Of Vehicle Repair" procedure.
▶ Go to "W/Harness Inspection" procedure.
Many malfunctions in the electrical system are caused by poor harness(es) and terminals. Faults can also be caused by interference from other electrical systems, and mechanical or chemical damage.
Thoroughly check connectors for looseness, poor connection, bending, corrosion, contamination, deterioration, or damage.
Has a problem been found?
▶ Repair as necessary and then go to "Verification Of Vehicle Repair" procedure.
▶ Go to "Power Circuit Inspection" procedure.
Ignition "OFF".
Disconnect HECU connector.
Ignition "ON".
Measure voltage between terminal "3" of the HECU harness connector and chassis ground.
Specification : Approx. B+
Is the measured voltage within specifications?
▶ Go to "Ground Circuit Inspection" procedure.
▶ Check for damaged harness and open or short to GND between the battery terminal(+) and terminal "3" of the HECU harness connector. Check for open or blown 40A ABS fuse referring to "Circuit Diagram". Repair as necessary and then go to "Verification of vehicle Repair" procedure.
Ignition "OFF".
Disconnect HECU connector.
Measure resistance between terminal "4" of the HECU harness connector and chassis ground.
Specification : Approx. below 1 Ω
Is the measured resistance within specifications?
▶ 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.
▶ Check for damaged harness and poor connection between terminal "4" of the HECU harness connector and chassis ground. Repair as necessary and then go to "Verification Of vehicle Repair" procedure.
After a repair, it is essential to verify that the fault has been corrected.
Connect scantool and select "Diagnostic Trouble Codes (DTCs)" mode
Using a scantool, Clear DTC.
Operate the vehicle within DTC Detecting Condition in General Information
Are any DTCs present?
▶ Go to the applicable troubleshooting procedure.
▶ System performing to specification at this time.
