ECM Power Source Circuit

DESCRIPTION

When the engine switch is turned to on, the battery voltage is applied to terminal IGSW of the ECM (Included in HV Control ECU). The ECM MREL output signal causes a current to flow to the coil, closing the contacts of the IGCT relay and supplying power to terminal +B of the ECM.
If the engine switch is turned to off, the ECM holds the IGCT relay ON for a maximum of 2 seconds to allow for the initial setting of the throttle valve.
When the ignition switch is turned ON, voltage from the ECM's MREL terminal flows to the IGCT relay. This causes the contacts of the IGCT relay to close, which supplies power to terminal +B or +B1 of the ECM.

WIRING DIAGRAM

INSPECTION PROCEDURE

1. INSPECT HV CONTROL ECU (+B, +B1 VOLTAGE)

1. Turn the ignition switch ON.

2. Measure the voltage between the terminals of the H31 and H32 HV Control ECU connectors.

   Standard voltage:

   Tester Connection	Specified Condition
   +B1 (H31-2) - E1 (H32-5)	9 to 14 V
   +B2 (H31-1) - E1 (H32-5)	9 to 14 V

OK	PROCEED TO NEXT CIRCUIT INSPECTION SHOWN ON PROBLEM SYMPTOMS TABLE

NG

2. CHECK HARNESS AND CONNECTOR (HV CONTROL ECU - BODY GROUND)

1. Disconnect the H32 HV Control ECU connector.

2. Measure the resistance between the HV Control ECU and body ground.

   Standard resistance (Check for open):

   Tester Connection	Specified Condition
   E1 (H32-5) - Body ground	Below 1 Ω

3. Reconnect the HV Control ECU connector.

NG	REPAIR OR REPLACE HARNESS AND CONNECTOR

OK

3. INSPECT HV CONTROL ECU (IGSW VOLTAGE)

1. Turn the ignition switch ON.

2. Measure the voltage between the terminals of the H29 and H32 HV Control ECU connectors.

   Standard voltage:

   Tester Connection	Specified Condition
   IGSW (H29-9) - E1 (H32-5)	9 to 14 V

OK	Go to step 6

NG

4. CHECK FUSE (IGN FUSE)

1. Remove the IGN fuse from the instrument panel J/B.

2. Measure the IGN fuse resistance.

   Standard resistance:

   Below 1 Ω
   

3. Reinstall the IGN fuse.

NG	CHECK FOR SHORT IN ALL HARNESSES AND COMPONENTS CONNECTED TO FUSE

OK

5. INSPECT IGNITION SWITCH ASSEMBLY

1. Check for continuity between the connector terminals shown in the chart below.

   Standard:

   Switch	Terminal No.	Resistance
   LOCK	All Terminals	No continuity
   ACC	1 - 2	Continuity
   ON	2 - 3, 2 - 4, 3 - 4, 6 - 7	Continuity
   START	1 - 2, 1 - 4, 2 - 4, 6 - 7, 6 - 8, 7 - 8	Continuity

NG	REPLACE IGNITION SWITCH ASSEMBLY

OK
PUSH HARNESS AND CONNECTOR (IGNITION SWITCH ASSEMBLY - HV CONTROL ECU)

6. INSPECT HV CONTROL ECU (MREL VOLTAGE)

1. Turn the ignition switch ON.

2. Measure the voltage between the terminals of the H31 and H32 HV Control ECU connectors.

   Standard voltage:

   Tester Connection	Specified Condition
   MREL (H31-12) - E1 (H32-5)	9 to 14 V

NG	REPLACE HYBRID VEHICLE CONTROL ECU

OK

7. CHECK FUSE (IGCT NO.2 FUSE)

1. Remove the IGCT No.2 fuse from the R/B No.3.

2. Measure the IGCT No.2 fuse resistance.

   Standard resistance:

   Below 1 Ω
   

3. Reinstall the IGCT No.2 fuse.

NG	CHECK FOR SHORT IN ALL HARNESSES AND COMPONENTS CONNECTED TO FUSE

OK

8. INSPECT IGCT RELAY

1. Remove the integration relay from the engine room R/B.

2. Measure the IGCT relay resistance.

   Standard resistance:

   Tester Connection	Specified Condition
   3 - 5	10 kΩ or higher
   	Below 1 Ω (Apply battery voltage between terminals 1 and 2)

NG	REPLACE INTEGRATION RELAY

OK

9. CHECK HARNESS AND CONNECTOR (IGCT RELAY- HV CONTROL ECU, IGCT RELAY - BODY GROUND)

1. Check the harness and the connectors between the integration relay and the HV Control ECU.

   1. Remove the IGCT relay from the engine room R/B.

   2. Disconnect the H31 HV Control ECU connector.

   3. Measure the resistance between the wire harness side connectors.

      Standard resistance (Check for open):

      Tester Connection	Specified Condition
      IGCT relay (1)- MREL (H31-12)	Below 1 Ω

      Standard resistance (Check for short):

      Tester Connection	Specified Condition
      IGCT relay (1) or MREL (H31-12) - Body ground	10 kΩ or higher

2. Check the harness and the connectors between the integration relay and body ground.

   1. Remove the integration relay from the engine room R/B.

   2. Measure the resistance between the wire harness side connector and body ground.

      Standard resistance (Check for open):

      Tester Connection	Specified condition
      IGCT relay (2) - Body ground	Below 1 Ω

NG	REPAIR OR REPLACE HARNESS AND CONNECTOR

OK
CHECK AND REPAIR HARNESS AND CONNECTOR (TERMINAL +B OF HV CONTROL ECU - BATTERY POSITIVE TERMINAL)