Aisin 81-40LE - Automatic Transmission (European Emissions)

DTC P1781 (European Emissions)

Conditions for Setting the DTC

* Transmission control module (TCM) detects that malfunction of engine speed signal for 2 seconds

* No DTC U2105

Action Taken When the DTC Sets

* TCM will request the illumination of the malfunction indicator lamp (MIL) and store the DTC when the TCM detects a failure on the 1st ignition cycle

* No engine torque reduction control

* No lock-up

* No engagement pressure control

* No 4th gear

* No self-learning control

* No timing solenoid control for N-D

* TCM judges the engine revolution is 0 RPM

Conditions for Clearing the DTC

* The TCM turns off the MIL when no further failures are detected on the next ignition cycles.

* The scan tool can clear the DTC from the TCM history.

* The TCM clears the DTC from the TCM history memory after 40 consecutive ignition cycles without fault.

Cause of Failure

* Wiring harness or connector between engine control module (ECM) and TCM

* ECM

* TCM