What Does P0855 Mean?
The drive switch input circuit is reading higher than the expected voltage threshold. This elevated signal typically results from a short to battery voltage in the wiring, an open ground wire, or a switch that has failed in a high-resistance state. The TCM cannot accurately interpret the gear selector position when the signal is out of range.
Common Causes
30%
Short to battery voltage in the drive switch wiring
30%
Faulty drive switch producing high-resistance output
20%
Open ground circuit at the drive switch
12%
Disconnected or corroded connector at the switch
8%
TCM input circuit fault
Diagnostic Steps
1
Monitor drive switch circuit voltage using the scan tool — verify if the voltage is abnormally high across all gear positions.
2
Disconnect the drive switch and check if voltage drops to near zero — if it remains high, there is a short to power in the harness.
3
Verify the switch ground circuit has proper continuity to chassis ground, as a floating ground will cause elevated signal voltage.
4
Trace the wiring harness and inspect for insulation damage near power sources or hot exhaust components.
5
Test the drive switch resistance in each selector position and replace if values are out of the manufacturer's specified range.
Estimated Repair Cost
$100 - $350
Parts + labor, varies by vehicle and location
The drive switch input circuit is reading higher than the expected voltage threshold. This elevated signal typically results from a short to battery voltage in the wiring, an open ground wire, or a switch that has failed in a high-resistance state. The TCM cannot accurately interpret the gear select...
The most common cause of P0855 (Drive Switch Input Circuit High) is: Short to battery voltage in the drive switch wiring
Typical repair costs for P0855 range from $100 to $350, depending on the vehicle, location, and whether you do it yourself or go to a shop.
Incorrect drive position detection may cause improper shift behavior, limp-mode activation, or failure to engage Drive. The vehicle may still be operable at reduced capacity, but repair should be prioritized.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to P0855 to identify the root cause.
OBDHut Mobile App
Scan codes directly from your car with the OBDHut app.
Coming Soon
Quick Info
Category
Powertrain
System
Transmission / Gear Selection
Difficulty
Type
Generic (SAE)
Recommended Tools
OBD2 Scanner
A quality scan tool helps you read codes, view live data, and clear faults.
