DTC P1840: CVT Speed Sensor Circuit Forward Rotation Range / Performance

NOTE: 

• Before you troubleshoot, review the General Troubleshooting Information - Refer to: HOW TO TROUBLESHOOT THE FUEL AND EMISSIONS SYSTEMS or How to Troubleshoot the CVT System(CVT) .
• This code is caused by an electrical circuit problem and cannot be caused by a mechanical problem in the transmission.

DTC (CVT)

1. CVT speed sensor check:

   - 1. Turn the vehicle to the ON mode.

   - 2. Clear the DTC with the HDS.

   - 3. Turn the vehicle to the OFF (LOCK) mode.

   - 4. Raise the vehicle on a lift. Make sure it is securely supported, and allow all four wheels to rotate freely.

   - 5. Start the engine.

   - 6. Disable the VSA by pressing the VSA OFF button (with VSA).

   - 7. Test-drive the vehicle in D position/mode, while monitoring the Direction of Secondary-shaft Rotation in the Data List with the HDS.

   - 8. Check the parameter(s) below with the HDS.

   Signal	Threshold		Current conditions
   	Values	Unit	Values	Unit
   Direction of Secondary-shaft Rotation	Forward

   Do the current condition(s) match the threshold?

   YES 

   The CVT speed sensor is OK. Update the PCM if it does not have the latest software , or substitute a known-good PCM , then recheck. If DTC P1840 goes away and the PCM was updated, troubleshooting is complete. If DTC P1840 goes away and the PCM was substituted, replace the original PCM .

   NO 

   Replace the CVT speed sensor .