P1915
DTC P1915
Circuit Description
The transmission internal mode switch (IMS) is a sliding contact switch attached to the selector detent inside the transmission side cover. The 4 inputs to the transmission control module (TCM) indicate the position of the transmission range selector. The input voltage level at the TCM is high, B+, when the IMS is open and low when the switch is closed to ground. The 4 input parameters represented are Signals A, B, C and P - Parity. Refer to Transmission Internal Mode Switch Logic.
If the TCM detects a combination of IMS signals that are invalid, or a transitional state between gear selector positions, while attempting to start the vehicle, then DTC P1915 sets. DTC P1915 is a type B DTC.
DTC Descriptor
This diagnostic procedure supports the following DTC:
DTC P1915 Internal Mode Switch Does Not Indicate Park/Neutral (P/N) During Start
Conditions for Running the DTC
* The system voltage is 9-18 volts.
* The ignition switch is in the START position for 2.5 seconds or more.
* The engine speed is 450 RPM or more.
Conditions for Setting the DTC
The IMS does not indicate PARK or NEUTRAL for 2 seconds when attempting to start the vehicle.
Action Taken When the DTC Sets
* The TCM requests the engine control module (ECM) to illuminate the malfunction indicator lamp (MIL) during the second consecutive trip in which the Conditions for Setting the DTC are met.
* The TCM commands maximum line pressure.
* The TCM freezes transmission adaptive functions.
* The ECM records the operating conditions when the Conditions for Setting the DTC are met. The ECM stores this information as Freeze Frame and Failure Records and the TCM records the operating conditions when the Conditions for Setting the DTC are met. The TCM stores this information as Failure Records.
* The TCM stores DTC P1915 in TCM history during the second consecutive trip in which the Conditions for Setting the DTC are met.
Conditions for Clearing the MIL/DTC
* The ECM turns OFF the MIL after the third consecutive drive trip in which the TCM does not send a MIL illumination request.
* The TCM clears the DIC message when the condition no longer exists.
* A scan tool can clear the MIL/DTC.
* The TCM clears the DTC from TCM history if the vehicle completes 40 warm-up cycles without an emission-related diagnostic fault occurring.
* The TCM cancels the DTC default actions when the ignition switch is OFF long enough in order to power down the TCM.
Test Description
The numbers below refer to the step numbers on the diagnostic table.
3. HI values for all signals in both Park and Drive 4 indicates the ground circuit is OPEN.
5. With the 20-way connector disconnected, all signals should indicate HI.
7. If one circuit affects the other, this indicates a short between the 2 circuits.
13. This step tests the internal transmission harness. If no fault is found in the harness, the fault will be in the switch.
