The P0854 code in your 2023 Lexus IS indicates the drive input signal circuit is providing a lower voltage than expected. This affects the transmission's ability to confirm when drive gear is selected.
Understanding Low Drive Signal
The IS uses electronic controls to detect gear selection. When the drive input voltage is low, the TCM may not properly recognize when a forward gear is selected, affecting vehicle operation.
Common Causes of P0854
- Short to ground in drive circuit
- High resistance reducing voltage
- Position sensor failure
- Wiring damage
- Connector corrosion
- Ground connection problems
Symptoms of Low Drive Signal
- Drive gear not recognized
- Check engine light on
- Gear display shows incorrect position
- Sport mode issues
- Transmission protection modes
- Possible no-drive condition
Lexus IS Performance Modes
The IS features Sport and Sport+ modes that require accurate gear position information. P0854 may disable these features until the underlying issue is resolved.