DTC P0A94 (48)
DTC P0A94 (48): DC-DC Converter Performance
General Description
The 12 volt battery voltage and the output voltage command measured by the battery condition monitor module A become within a prescribed range if the DC-DC converter is normally operating. If a malfunction of the DC-DC converter occurs or if the DC-DC converter output stops (for protection) due to overheating, the 12 volt battery voltage decreases. Malfunction of the DC-DC converter is detected and a DTC is stored when any of the following conditions is met:
- Malfunction judgment 1
The battery condition monitor module A compares the value of the DC-DC converter output voltage commanded by the battery condition monitor module A with the 12 volt battery voltage read by the battery condition monitor module A and the difference between them is a prescribed value or more for a prescribed time or the battery condition monitor module A receives internal failure information sent from the DC-DC converter after the DC-DC converter performs the same procedures as what the battery condition monitor module A does.
- Malfunction judgment 2
The DC-DC converter sends internal malfunction information if the DC-DC converter output voltage is lower than the commanded voltage. The battery condition monitor module A receives the malfunction information from the DC-DC converter for a specified duration.
- Malfunction judgment 3
The 12 volt battery voltage is a specified value or less for a set time.
Monitor Execution, Sequence, Duration, DTC Type
| Execution | Continuous |
| Sequence | None |
| Duration | - |
| DTC Type | One drive cycle, MIL off, POWER SYSTEM indicator off, 12 volt battery charging system indicator on |
Enable Conditions
| Condition | Minimum | Maximum |
|---|---|---|
| Battery condition monitor module A power-supply voltage | 10.2 V | - |
| Inverter voltage | 225.0 V | 345.0 V |
| Vehicle condition | Vehicle ON mode, or Plug-in charge on, or Plug-in quick charge on | |
Malfunction Threshold
When any of the following conditions is met, a malfunction is detected.
- Malfunction judgment 1
The difference between the commanded DC-DC converter voltage and the 12 volt battery voltage is 2.5 V or more for at least 60 seconds.
- Malfunction judgment 2
The battery condition monitor module A receives the internal malfunction information from the DC-DC converter for at least 2 seconds.
- Malfunction judgment 3
The 12 volt battery voltage value which the battery condition monitor module A recognizes is less than 11 V for at least 60 seconds.
Possible Cause
- DC-DC converter output line open (internal resistance increase, or contact resistance increase)
- DC-DC converter internal circuit failure
- Battery condition monitor module A internal circuit failure
Confirmation Procedure
Operating condition
Turn the vehicle to the ON mode, and wait 100 seconds.
With the HDS
None.
Diagnosis Details
Conditions for setting the DTC
When a malfunction is detected, the 12 volt battery charging system indicator comes on and a Pending DTC, a Confirmed DTC, and the freeze data are stored in the battery condition monitor module A memory. The POWER SYSTEM indicator does not come on.
Conditions for clearing the DTC
The 12 volt battery charging system indicator is cleared if the malfunction does not return in the next trip in which the diagnostic runs. The 12 volt battery charging system indicator, the Pending DTC, the Confirmed DTC, and the freeze data can be cleared with the scan tool Clear command.