Circuit Description
Throttle position information is sent to the transmission control module (TCM) by the engine control module (ECM) through a communication network called the controller area network (CAN). Two circuits are used to communicate CAN data between the ECM and TCM. A fault in the CAN will not cause DTC P1890 to set by itself. If a CAN fault occurs, other DTCs will set before DTC P1890.
When the ECM sends the TCM throttle position information that is unreliable, DTC P1890 will set. DTC P1890 is a type B DTC.
Condition for Running the DTC
The ignition is ON.
Condition for Setting the DTC
The throttle position value is unreliable for 1 second.
Action Taken When the DTC Sets
| • | The TCM flashes the sport mode lamp and sends a MIL request to the ECM on the second consecutive drive trip that the diagnostic runs and fails. The ECM then illuminates the MIL. |
| • | The ECM records the operating conditions in the Freeze Frame at the time of the MIL request from the TCM. |
| • | The transmission operates in the default mode (maximum line pressure, command 4th gear, inhibit TCC, freeze shift adapts). |
Conditions For Clearing the MIL/DTC
| • | The ECM turns off the MIL after three consecutive drive trips during which the TCM sends no MIL request. |
| • | A History DTC clears after forty consecutive warm-up cycles, if no failures are present by this diagnostic or any other emission related diagnostic. |
| • | The scan tool clears the MIL/DTC. |
| • | The TCM cancels the DTC default mode actions when the ignition switch is Off long enough in order to power down the TCM. |
Step | Action | Value(s) | Yes | No | ||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
1 | Did you perform Powertrain On Board Diagnostic (OBD) System Check - Automatic Transmission ? | -- | Go to Powertrain On Board Diagnostic (OBD) System Check - Automatic Transmission | |||||||||
2 |
Important: Record all Failure Records before clearing the DTC. Using Clear Info erases the Failure Records from the ECM and TCM. Did you record any ECM Failure Records? | -- | Go to the applicable ECM DTC | |||||||||
3 | Did you record Failure Records for any of the following DTCs?
| -- | Go to the applicable CAN Bus DTC | |||||||||
4 |
Did DTC P1890 reset? | -- | Go to Intermittent Conditions in Engine Controls | |||||||||
5 | Did any other DTCs set? | -- | Go to the applicable DTC | |||||||||
6 | Replace the ECM. Refer to Engine Control Module Replacement . Is the action complete? | -- | -- | |||||||||
7 | Perform the following operation to verify the repair:
Did DTC P1890 reset? | -- | System OK |
