Lexus ES: ECU Power Source Circuit
DESCRIPTION
If the power switch is on (IG), the hybrid vehicle control ECU applies current to the MREL terminal to turn the IGCT relay on. This supplies power to the +B1 and +B2 terminals.
WIRING DIAGRAM
CAUTION / NOTICE / HINT
NOTICE:
After turning the power switch off, waiting time may be required before disconnecting the cable from the negative (-) auxiliary battery terminal. Therefore, make sure to read the disconnecting the cable from the negative (-) auxiliary battery terminal notices before proceeding with work.
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PROCEDURE
| 1. | CHECK HYBRID VEHICLE CONTROL ECU (+B1, +B2 VOLTAGE) |
(a) Turn the power switch on (IG).
| (b) Measure the voltage according to the value(s) in the table below. Standard Voltage:
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|
(c) Turn the power switch off.
| NG | .gif) | GO TO STEP 3 |
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| 2. | CHECK HARNESS AND CONNECTOR (HYBRID VEHICLE CONTROL ECU - BODY GROUND) |
(a) Disconnect the G59 and G60 hybrid vehicle control ECU connectors.
| (b) Measure the resistance according to the value(s) in the table below. Standard Resistance:
|
|
(c) Reconnect the G59 and G60 hybrid vehicle control ECU connectors.
| OK | | GO TO PROBLEM SYMPTOMS TABLE |
| NG | | REPAIR OR REPLACE HARNESS OR CONNECTOR |
| 3. | CHECK HYBRID VEHICLE CONTROL ECU (MREL VOLTAGE) |
(a) Turn the power switch on (IG).
| (b) Measure the voltage according to the value(s) in the table below. Standard Voltage:
|
|
(c) Turn the power switch off.
| NG | | REPLACE HYBRID VEHICLE CONTROL ECU |
|
| 4. | CHECK FUSE (PM-IGCT) |
| (a) Remove the PM-IGCT fuse from the No. 4 relay block. |
|
(b) Measure the resistance according to the value(s) in the table below.
Standard Resistance:
| Tester Connection | Condition | Specified Condition |
|---|---|---|
| PM-IGCT fuse | Always | Below 1 Ω |
(c) Install the PM-IGCT fuse.
| NG | | GO TO STEP 12 |
|
| 5. | CHECK FUSIBLE LINK BLOCK ASSEMBLY (IGCT FUSE) |
(a) Disconnect the cable from the negative (-) auxiliary battery terminal.
(b) Disconnect the cable from the positive (+) auxiliary battery terminal.
| (c) Disconnect the 7A fusible link block assembly connector. |
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| (d) Measure the resistance according to the value(s) in the table below. Standard Resistance:
|
|
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(e) Reconnect the 7A fusible link block assembly connector.
(f) Reconnect the cable to the positive (+) auxiliary battery terminal.
(g) Reconnect the cable to the negative (-) auxiliary battery terminal.
| NG | | GO TO STEP 13 |
|
| 6. | INSPECT RELAY (IGCT) |
| (a) Remove the IGCT relay from the No. 3 relay block. |
|
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| (b) Measure the resistance according to the value(s) in the table below. Standard Resistance:
|
|
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(c) Install the IGCT relay.
| NG | | REPLACE RELAY (IGCT) |
|
| 7. | CHECK HARNESS AND CONNECTOR (NO. 4 RELAY BLOCK - HYBRID VEHICLE CONTROL ECU) |
(a) Disconnect the A32 and A33 hybrid vehicle control ECU connectors.
(b) Remove the PM-IGCT fuse from the No. 4 relay block.
(c) Measure the resistance according to the value(s) in the table below.
| *1 | No. 4 Relay Block | *2 | PM-IGCT Fuse Holder |
| *a | Rear view of wire harness connector (to Hybrid Vehicle Control ECU) | - | - |
Standard Resistance:
| Tester Connection | Condition | Specified Condition |
|---|---|---|
| A33-4 (+B1) - 2 (PM-IGCT fuse holder) | Always | Below 1 Ω |
| A32-1 (+B2) - 2 (PM-IGCT fuse holder) | Always | Below 1 Ω |
(d) Reconnect the A32 and A33 hybrid vehicle control ECU connectors.
(e) Install the PM-IGCT fuse.
| NG | | REPAIR OR REPLACE HARNESS OR CONNECTOR |
|
| 8. | CHECK HARNESS AND CONNECTOR (NO. 3 RELAY BLOCK - NO. 4 RELAY BLOCK) |
(a) Remove the IGCT relay from the No. 3 relay block.
(b) Remove the PM-IGCT fuse from the No. 4 relay block.
(c) Measure the resistance according to the value(s) in the table below.
| *1 | No. 3 Relay Block | *2 | No. 4 Relay Block |
| *3 | IGCT Relay Holder | *4 | PM-IGCT Fuse Holder |
Standard Resistance:
| Tester Connection | Condition | Specified Condition |
|---|---|---|
| 5 (IGCT relay holder) - 1 (PM-IGCT fuse holder) | Always | Below 1 Ω |
(d) Install the PM-IGCT fuse.
(e) Install the IGCT relay.
| NG | | REPAIR OR REPLACE HARNESS OR CONNECTOR |
|
| 9. | CHECK HARNESS AND CONNECTOR (FUSIBLE LINK BLOCK ASSEMBLY - NO. 3 RELAY BLOCK) |
(a) Disconnect the 7A fusible link block assembly connector.
| (b) Remove the IGCT relay from the No. 3 relay block. |
|
(c) Measure the resistance according to the value(s) in the table below.
Standard Resistance:
| Tester Connection | Condition | Specified Condition |
|---|---|---|
| 3 (IGCT relay holder) - 7A-1 | Always | Below 1 Ω |
(d) Install the IGCT relay.
(e) Reconnect the 7A fusible link block assembly connector.
| NG | | REPAIR OR REPLACE HARNESS OR CONNECTOR |
|
| 10. | CHECK HARNESS AND CONNECTOR (HYBRID VEHICLE CONTROL ECU - NO. 3 RELAY BLOCK) |
(a) Disconnect the A33 hybrid vehicle control ECU connector.
(b) Remove the IGCT relay from the No. 3 relay block.
(c) Measure the resistance according to the value(s) in the table below.
| *1 | No. 3 Relay Block | *2 | IGCT Relay Holder |
| *a | Rear view of wire harness connector (to Hybrid Vehicle Control ECU) | - | - |
Standard Resistance:
| Tester Connection | Condition | Specified Condition |
|---|---|---|
| A33-6 (MREL) - 1 (IGCT relay holder) | Always | Below 1 Ω |
| A33-6 (MREL) or 1 (IGCT relay holder) - Body ground and other terminals | Always | 10 kΩ or higher |
(d) Install the IGCT relay.
(e) Reconnect the A33 hybrid vehicle control ECU connector.
| NG | | REPAIR OR REPLACE HARNESS OR CONNECTOR |
|
| 11. | CHECK HARNESS AND CONNECTOR (NO. 3 RELAY BLOCK - BODY GROUND) |
(a) Remove the IGCT relay from the No. 3 relay block.
| (b) Measure the resistance according to the value(s) in the table below. Standard Resistance:
|
|
(c) Install the IGCT relay.
| OK | | CHECK FOR INTERMITTENT PROBLEMS |
| NG | | REPAIR OR REPLACE HARNESS OR CONNECTOR |
| 12. | CHECK HARNESS AND CONNECTOR (NO. 4 RELAY BLOCK - HYBRID VEHICLE CONTROL ECU) |
(a) Remove the PM-IGCT fuse from the No. 4 relay block.
(b) Disconnect the A32 and A33 hybrid vehicle control ECU connectors.
(c) Measure the resistance according to the value(s) in the table below.
| *1 | No. 4 Relay Block | *2 | PM-IGCT Fuse Holder |
| *a | Rear view of wire harness connector (to Hybrid Vehicle Control ECU) | - | - |
Standard Resistance:
| Tester Connection | Condition | Specified Condition |
|---|---|---|
| A33-4 (+B1) or 2 (PM-IGCT fuse holder) - Body ground and other terminals | Always | 10 kΩ or higher |
| A32-1 (+B2) or 2 (PM-IGCT fuse holder) - Body ground and other terminals | Always | 10 kΩ or higher |
(d) Reconnect the A32 and A33 hybrid vehicle control ECU connectors.
(e) Install the PM-IGCT fuse.
| OK | | REPLACE FUSE (PM-IGCT) |
| NG | | GO TO STEP 15 |
| 13. | CHECK HARNESS AND CONNECTOR (FUSIBLE LINK BLOCK ASSEMBLY - NO. 3 RELAY BLOCK) |
(a) Disconnect the 7A fusible link block assembly connector.
(b) Remove the IGCT relay from the No. 3 relay block.
| (c) Measure the resistance according to the value(s) in the table below. Standard Resistance:
|
|
(d) Install the IGCT relay.
(e) Reconnect the 7A fusible link block assembly connector.
| NG | | GO TO STEP 16 |
|
| 14. | CHECK HARNESS AND CONNECTOR (NO. 3 RELAY BLOCK - NO. 4 RELAY BLOCK) |
(a) Remove the IGCT relay from the No. 3 relay block.
(b) Remove the PM-IGCT fuse from the No. 4 relay block.
(c) Measure the resistance according to the value(s) in the table below.
| *1 | No. 3 Relay Block | *2 | No. 4 Relay Block |
| *3 | IGCT Relay Holder | *4 | PM-IGCT Fuse Holder |
Standard Resistance:
| Tester Connection | Condition | Specified Condition |
|---|---|---|
| 5 (IGCT relay holder) or 1 (PM-IGCT fuse holder) - Body ground and other terminals | Always | 10 kΩ or higher |
(d) Install the PM-IGCT fuse.
(e) Install the IGCT relay.
| OK | | REPLACE FUSIBLE LINK BLOCK ASSEMBLY (IGCT FUSE) |
| NG | | GO TO STEP 17 |
| 15. | REPAIR OR REPLACE HARNESS OR CONNECTOR |
| NEXT | | REPLACE FUSE (PM-IGCT) |
| 16. | REPAIR OR REPLACE HARNESS OR CONNECTOR |
| NEXT | | REPLACE FUSIBLE LINK BLOCK ASSEMBLY (IGCT FUSE) |
| 17. | REPAIR OR REPLACE HARNESS OR CONNECTOR |
| NEXT | | REPLACE FUSIBLE LINK BLOCK ASSEMBLY (IGCT FUSE) |
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