DESCRIPTION
WIRING DIAGRAM
INSPECTION PROCEDURE
INSPECT ALTERNATOR
CHECK HARNESS AND CONNECTOR (POWER HEATER ECU (COMBUSTION HEATER ASSEMBLY) - ALTERNATOR)
CHECK HARNESS AND CONNECTOR (POWER HEATER ECU (COMBUSTION HEATER ASSEMBLY) - BATTERY)
COMBUSTION TYPE POWER HEATER SYSTEM - Power Heater Alternator Circuit
DESCRIPTION
When the alternator does not generate electricity, current flows from the IG2 relay to power heater resistors No. 1 and No. 2. Then the current flows to the diode (for power heater), terminal E82-4 (L) of the alternator, and then to ground. As a result, the power heater ECU will not activate.
When the alternator generates electricity, the current flows from the IG2 relay to power heater resistors No. 1 and No. 2, and then to terminal A51-8 (+), and the power heater ECU determines that the engine is running.
WIRING DIAGRAM
INSPECTION PROCEDURE
Inspect the alternator (for ON-VEHICLE INSPECTION, for INSPECTION).
| 2.CHECK HARNESS AND CONNECTOR (POWER HEATER ECU (COMBUSTION HEATER ASSEMBLY) - ALTERNATOR) |
Disconnect the connector from the power heater ECU (combustion heater assembly).
Disconnect the connector from the alternator.
Measure the resistance according to the value(s) in the table below.
- Standard resistance:
Tester connection
(Symbols) | Condition | Specified condition |
| A51-8 (+) - E82-4 (L) | Always | Below 1 Ω |
| A51-8 (+) - Body ground | Always | 10 kΩ or higher |
| | REPAIR OR REPLACE HARNESS OR CONNECTOR (POWER HEATER ECU (COMBUSTION HEATER ASSEMBLY) - ALTERNATOR) |
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| 3.CHECK HARNESS AND CONNECTOR (POWER HEATER ECU (COMBUSTION HEATER ASSEMBLY) - BATTERY) |
Reconnect the connector to the alternator.
Measure the voltage according to the value(s) in the table below.
- Standard voltage:
Tester connection
(Symbols) | Condition | Specified condition |
| A51-8 (+) - Body ground | Engine is running.
(Alternator: Operate) | 10 to 14 V |
| | REPAIR OR REPLACE HARNESS OR CONNECTOR (POWER HEATER ECU (COMBUSTION HEATER ASSEMBLY) - BATTERY) |
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| OK | |
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| PROCEED TO NEXT CIRCUIT INSPECTION SHOWN IN PROBLEM SYMPTOMS TABLE |
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LEXUS IS250, IS220d / GSE20 ALE20
