DTC Advanced Diagnostics: P0641 (A/T System)
DTC P0641 : Sensor Reference Voltage 1 Circuit Malfunction
General Description
The transmission control module (TCM) is equipped with a sensor supply (5 V power source) to supply a stable 5 V to each sensor as reference voltage. The correct voltages for the sensors are loaded in the CPU of the TCM (A/D input) and when the sensor supply voltage (VCC1) is a set value (high or low) for a certain time, the TCM detects a malfunction and stores a DTC.
Monitor Execution, Sequence, Duration, DTC Type
| Execution | Continuous |
| Sequence | None |
| Duration | 0.25 second or more |
| DTC Type | One drive cycle, MIL on, shift position indicator blinks |
Enable Conditions
| Condition | Minimum | Maximum |
|---|---|---|
| 12 volt battery voltage [Battery Voltage] | 10 V | - |
| Vehicle | ON mode | |
[ ]: HDS Parameter
Malfunction Threshold
The sensor supply voltage (VCC1) is more than 7.2 V, or less than 2 V, for at least 0.25 second.
Possible Cause
- Mainshaft speed sensor failure
- Solenoid wire harness failure
- TCM internal circuit failure
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.