Lexus ES: DC/DC Converter Status Circuit Short to Battery (P0A0812,P0A0814)
DESCRIPTION
The DC/DC converter varies output voltage based on voltage change signals (VLO signal line) received from the motor generator control ECU.
If the vehicle is being driven with an inoperative DC/DC converter, the voltage of the auxiliary battery will drop, which will prevent the continued operation of the vehicle. Therefore, the motor generator control ECU monitors the operation of the DC/DC converter and alerts the driver if it detects a malfunction.
| DTC No. | Detection Item | DTC Detection Condition | Trouble Area | MIL | Warning Indicate |
|---|---|---|---|---|---|
| P0A0812 | DC/DC Converter Status Circuit Short to Battery | Short to +B detected in DC/DC converter VLO signal line (1 trip detection logic) |
| Does not come on | Master Warning Light: Comes on |
| P0A0814 | DC/DC Converter Status Circuit Short to Ground or Open | Open or short to ground detected in DC/DC converter VLO signal line (1 trip detection logic) |
| Does not come on | Master Warning Light: Comes on |
CONFIRMATION DRIVING PATTERN
HINT:
After repair has been completed, clear the DTC and then check that the vehicle has returned to normal by performing the following All Readiness check procedure.
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- Connect the Techstream to the DLC3.
- Turn the power switch on (IG) and turn the Techstream on.
- Clear the DTCs (even if no DTCs are stored, perform the clear DTC procedure).
- Turn the power switch off and wait for 2 minutes or more.
- Turn the power switch on (IG) and turn the Techstream on.
- With power switch on (IG) and wait for 10 seconds or more.
- Enter the following menus: Powertrain / Motor Generator / Utility / All Readiness.
-
Check the DTC judgment result.
HINT:
- If the judgment result shows NORMAL, the system is normal.
- If the judgment result shows ABNORMAL, the system has a malfunction.
- If the judgment result shows INCOMPLETE or N/A, perform driving pattern again.
WIRING DIAGRAM
Refer to the wiring diagram for the DTC P0A1112.
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CAUTION / NOTICE / HINT
CAUTION:
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Before the following operations are conducted, take precautions to prevent electric shock by turning the power switch off, wearing insulated gloves, and removing the service plug grip from HV battery.
- Inspecting the high-voltage system
- Disconnecting the low voltage connector of the inverter with converter assembly
- Disconnecting the low voltage connector of the HV battery
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To prevent electric shock, make sure to remove the service plug grip to cut off the high voltage circuit before servicing the vehicle.
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After removing the service plug grip from the HV battery, put it in your pocket to prevent other technicians from accidentally reconnecting it while you are working on the high-voltage system.
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After removing the service plug grip, wait for at least 10 minutes before touching any of the high-voltage connectors or terminals. After waiting for 10 minutes, check the voltage at the terminals in the inspection point in the inverter with converter assembly. The voltage should be 0 V before beginning work.
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HINT:
Waiting for at least 10 minutes is required to discharge the high-voltage capacitor inside the inverter with converter assembly.
*a
Without waiting for 10 minutes
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 CONNECTOR CONNECTION CONDITION (INVERTER WITH CONVERTER ASSEMBLY CONNECTOR) |
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| Result | Proceed to |
|---|---|
| OK | A |
| NG (The connector is not connected securely.) | B |
| NG (The terminals are not making secure contact or are deformed, or water or foreign matter exists in the connector.) | C |
| B | .gif) | CONNECT SECURELY |
| C | | REPAIR OR REPLACE HARNESS OR CONNECTOR |
|
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| 2. | CHECK HARNESS AND CONNECTOR (INVERTER WITH CONVERTER ASSEMBLY - IGCT RELAY) |
CAUTION:
Be sure to wear insulated gloves.
(a) Check that the service plug grip is not installed.
NOTICE:
After removing the service plug grip, do not turn the power switch on (READY), unless instructed by the repair manual because this may cause a malfunction.
(b) Disconnect the A58 inverter with converter assembly connector.
(c) Remove the IGCT relay from the No.3 relay block.
(d) Measure the resistance according to the value(s) in the table below.
| *1 | No.3 Relay Block | *2 | IGCT Relay |
| *a | Front view of wire harness connector (to Inverter with Converter Assembly) | - | - |
Standard Resistance:
| Tester Connection | Condition | Specified Condition |
|---|---|---|
| A58-12 (IGCT) - 5 (IGCT relay) | Power switch off | Below 1 Ω |
(e) Install the IGCT relay.
(f) Reconnect the A58 inverter with converter assembly connector.
| OK | | REFER TO REPLACE INVERTER WITH CONVERTER ASSEMBLY PARTS |
| NG | | REPAIR OR REPLACE HARNESS OR CONNECTOR |
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