DTC P1AF5 (2024 2025)
DTC P1AF5 : VB3 Voltage Correlation Abnormality
General Description
The voltage input to the VB3 terminal of the transmission control module (TCM) is detected by the voltage divider circuit inside the TCM. If the resistor in the voltage divider circuit fails and the resistance increases or decreases, the VB3 terminal voltage cannot be detected correctly. The failure is detected by comparing the VB3 terminal voltage of the TCM with the system voltage of the powertrain control module (PCM), and if certain voltage difference occurs for a set time, the TCM detects a malfunction and stores a DTC.
Monitor Execution, Sequence, Duration, DTC Type
| Execution | Continuous |
| Sequence | None |
| Duration | 10 seconds or more |
| DTC Type | Two drive cycles, MIL on, Shift position indicator blinks |
Enable Conditions
| Condition | Minimum | Maximum |
|---|---|---|
| Elapsed time after the vehicle condition is turned to the ON mode | 3 seconds | - |
| State of the engine | Running | |
| Other | Input voltage of at least one unit of TCM or PCM is 16 V or less | |
Malfunction Threshold
The voltage difference between VB3 terminal voltage of the TCM and the system voltage of the PCM is specified value or more for at least 10 seconds.
Possible Cause
NOTE: The causes shown may not be a complete list of all potential problems, and it is possible that there may be other causes.
- TCM VB3 line failure
- PCM internal circuit failure
- TCM internal circuit failure (resistor 1 resistance and resistor 2 resistance increase/resistor 1 resistance and resistor 2 resistance decrease)
Confirmation Procedure
Operating Condition
Start the engine, and let it idle for at least 13 seconds.
Diagnosis Details
Conditions for setting the DTC
When a malfunction is detected during the first drive cycle, a Pending DTC is stored in the TCM memory. If the malfunction returns in the next (second) drive cycle, the MIL comes on, the shift position indicator blinks, and a Confirmed DTC and the freeze data are stored.
Conditions for clearing the DTC
The shift position indicator comes off by turning the vehicle to the OFF (LOCK) mode. The MIL is cleared if the malfunction does not return in three consecutive trips in which the diagnostic runs. The MIL, the Pending DTC, the Confirmed DTC, and the freeze data can be cleared with the scan tool clear command.