DTC P1AF2 (A/T System) (2024 2025)
DTC P1AF2 : VB2 Voltage Out of Range
General Description
The voltage input to the VB2 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 VB2 terminal voltage cannot be detected correctly. If the VB2 terminal voltage detected by the voltage divider circuit is out of specified value for a set time, the TCM detects a malfunction and stores a DTC.
Monitor Execution, Sequence, Duration, DTC Type
| Execution | Continuous |
| Sequence | None |
| Duration | 6 seconds or more |
| DTC Type | Two drive cycles, MIL on, Shift position indicator blinks |
Enable Conditions
Enable condition for detecting high voltage side
| Condition | Minimum | Maximum |
|---|---|---|
| Elapsed time after the vehicle condition is turned to the ON mode | 3 seconds | - |
| Other | Input voltage of at least one unit of TCM or powertrain control module (PCM) is 16 V or less | |
Enable condition for detecting low voltage side
| Condition | ||
|---|---|---|
| Vehicle | ON mode | |
Malfunction Threshold
The VB2 terminal voltage detected by the voltage divider circuit is out of specified value for at least 6 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 VB2 line failure
- TCM internal circuit failure (resistor 1 resistance decrease and resistor 2 resistance increase/resistor 1 resistance increase and resistor 2 resistance decrease)
Confirmation Procedure
Operating Condition
Turn the vehicle to the ON mode, and wait for at least 9 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.