The TCM/ECU uses data from the transmission fluid pressure manual valve position switch / TFP manual valve position switch to set the correct line pressure for the selected gear. If you have a P1816 diagnostic trouble code, the TFT manual valve position switch thinks Park/Neutral is selected, when a Drive ratio is actually indicated .
How Serious is the Code?
If the line pressure is too high or too low, the transmission will not function properly and there may be significant damage to the internal components.
Symptoms of a P1816 DTC include:
- Unusually harsh shifts
- Check engine light
- Limp Mode
- Failed transmission fluid pressure manual valve position switch/TFP switch
- Short in the TFP valve position switch wiring harness
- Poor connection in the TFP valve positions switch circuit
How to Diagnose the Code?
To diagnose a P1816 DTC, a technician will have to perform electrical tests to see if the transmission fluid pressure manual valve position switch is able to detect the gear being selected.
What Repairs Will Fix P1816?
Repair any electrical shorts in the transmission fluid pressure manual valve position sensor circuit
Replace the TFP sensor
P1810 – Transmission Fluid Pressure Manual Valve Position Switch
P1818 – Transmission Fluid Pressure Manual Valve Position Switch indicates Drive without Drive ratio