The Powertrain Control Module (PCM) monitors the Torque Converter Clutch (TCC)
slip by calculating the difference between the engine speed and the transmission output shaft speed. When the PCM
detects an excessive amount of slip when the TCC is engaged, then DTC P1870 sets. DTC P1870 is a type A DTC.
- Ensure that the vehicle'* final drive ratio matches the PCM'* calibration.
- Ensure that the transmission will shift through all four gears with the gear select lever in the D4 range.