4.
Inspect opearating status of inlet valve with Actuation Test.
Specification : It's normal if operating sound is heard.
The HECU supplies battery power to the electric motor with a motor relay which is controlled by the Electronic Control Unit(ECU). The electric motor pump supplies hydraulic pressure to all wheel brake calipers by operating the piston inside the pump.
The HECU monitors the pump motor relay or fuse open, open or short in motor or motor lock and then sets this code if a malfunction is detected. Warning lamp is turned OFF unless fault is detected any more when the IG KEY is turned ON again, and wheel speed is more than 15 km/h.
Item | Detecting Condition | Possible cause | |
DTC Strategy | ● Voltage monitoring | ● Open or short of power supply circuit (ABS1) ● Faulty HECU | |
Case1 (Stop monitor) | Monitoring Period | ● Stop monitor is active if the pump is off i.e. not actuation and no Slowdown. | |
Enable Conditions | ● A failure is detected if the pump motor voltage ＞ 2.0 V for more than 1 s. | ||
Fail Safe | ● The return pump does not work correct. ● The ABS/ESP functions are inhibited, reduced function of the EBD system. ● The ABS/EBD/ESP warning lamps are activated. | ||
Case2 (Pump run monitor) | Monitoring Period | ● The monitor is active if the pump is switched on | |
Enable Conditions | ● A failure is detected if the pump motor voltage ＜ (battery voltage - 4.0 V) for more than 100ms. | ||
Fail Safe | ● Pressure decrease (outlet valve) is no longer possible. ● The ABS/ESP functions are inhibited, reduced function of the EBD system. ● The ABS/EBD/ESP warning lamps are activated. | ||
Case3 (Pump slowdown monitor) | Monitoring Period | ● Monitor is always active in the transition "pump on → pump off" | |
Enable Conditions | ● After the end of the actuation of the motor relay has, the pump motor is still in motion and is generating a Voltage during it.s slowdown. The generated UM is monitored for a certain time on high level. The time depends on the supply voltage and is in the range of t = 30 ms to t = 125 ms.If the slow down condition isn.t met, the pump is activated again (see actuation times below) and the slowdown time is measured again. This is repeated for maximum n = 3 times. If, after the last pump activation, the pump motor slowdown time is still to short, a failure is detected. Actuation times: 1st actuation: 200 ms 2nd actuation: 1000 ms 3rd actuation: 3000 ms | ||
Fail Safe | ● Pressure decrease (outlet valve) is no longer possible. ● The ABS/ESP functions are inhibited, reduced function of the EBD system. ● 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 inlet valve with Actuation Test.
Specification : It's normal if operating sound is heard.
Does a inlet valve operate normally?
▶ Fault is intermittent caused by faulty valve or was repaired and HECU memory was not cleared. Go to the pplicable troubleshooting procedure.
▶ Go to "Component 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 "2" 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 "2" 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 "1" of the HECU harness connector and chassis ground.
Specification : Approx. below 1 Ω
Is the measured resistance within specifications?
▶ Go to "Component Inspection" procedure.
▶ Check for damaged harness and poor connection between terminal "1" of the HECU harness connectorand chassis ground. Repair as necessary and then go to "Verification of vehicle Repair" procedure.
Ignition "OFF".
Engine "ON".
Start and drive vehicle in gear and maintain vehicle speed is approx. 15 km/h or more(9 mph or more).
Does warning lamp remain On?
▶ 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.
▶ Fault is intermittent caused by poor connection in power harness (IGN+), faulty Alternator and/or faulty HECU or was repaired and HECU memory was not cleared. Go to the applicable roubleshooting 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.
