DTC Advanced Diagnostics: P2685, P2686
DTC P2685 : Actuator Supply Voltage C Circuit Low DTC P2686 : Actuator Supply Voltage C Circuit High
General Description
The actuator supply voltage is for the power to drive the CPU in the transmission control module (TCM). From the perspective of a fail-safe, three systems (VB1, VB2, and VB3) of the power supply lines are secured. They also have a role to supply power to the clutch pressure control solenoid valves and the shift solenoid valves. The TCM monitors whether the VB3 voltage is in a normal range by the CPU. If the VB3 voltage is a 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* | 0.5 second or more |
| Duration** | 0.6 second or more |
| DTC Type | One drive cycle, MIL on, shift position indicator blinks |
*: DTC P2685
**: DTC P2686
Enable Conditions
| Condition | Minimum | Maximum |
|---|---|---|
| Elapsed time after the vehicle condition is turned to the OFF (LOCK) mode** | 30 seconds | - |
| 12 volt battery voltage [Battery Voltage] | 10 V | - |
| Vehicle | ON mode | |
| Other* | Fail-safe switch is on (actuator power supplied state) | |
[ ]: HDS Parameter
Malfunction Threshold
DTC: P2685
The VB3 voltage is 5.6 V or less for at least 0.5 second.
DTC: P2686
The VB3 voltage is 7.2 V or more for at least 0.6 second.
Possible Cause
DTC: P2685
- Fuse failure
- Short in fuse circuit
- TCM VB3 line open (includes a loose or disconnected connector)
Common
- TCM internal circuit failure
Confirmation Procedure
Operating Condition
DTC: P2685
Turn the vehicle to the ON mode, and wait for several seconds.
DTC: P2686
- Turn the vehicle to the ON mode.
- Turn the vehicle to the OFF (LOCK) mode, and wait for at least 30 seconds.
- Turn the vehicle to the ON mode, and wait for several seconds.
Diagnosis Details
Conditions for setting the DTC
When a malfunction is detected, the MIL comes on, the shift position indicator blinks, and a Pending DTC, a Confirmed DTC, and the freeze data are stored in the TCM memory.
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.