P1915

DTC P1915





Circuit Description

The transmission manual shift shaft switch assembly is a sliding contact switch attached to the control valve body within the transmission. The four inputs to the transmission control module (TCM) from the switch indicate which position is selected by the transmission selector lever. This information is used for engine controls as well as determining the transmission shift patterns. The input voltage at the TCM is high when the switch is open and low when the switch is closed to ground. The state of each input is displayed on the scan tool as IMS. The IMS input parameters represented are transmission range Signal A , Signal B, Signal C and Signal P.

If the TCM detects an invalid switch state while the engine is being started, 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 engine speed is greater than 500 RPM.
* A CRANK request signal has been requested for 409 seconds or more.

Conditions for Setting the DTC

The IMS does not indicate PARK or NEUTRAL for 2 seconds or more when attempting to start the vehicle.

Action Taken When the DTC Sets

* The TCM requests the 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 commands an alternate coast shift pattern where downshifts occur at higher vehicle speeds while coasting.
* The TCM freezes transmission adaptive functions.
* The TCM disables TAP Shift operation.
* The TCM assumes a D4 shift pattern.
* At the time of the first failure, the TCM records the operating conditions when the Conditions for Setting the DTC are met. The TCM stores this information as a Failure Record.
* At the time of the second failure, the ECM records the operating conditions when the Conditions for Setting the DTC are met. The ECM stores this information as a Freeze Frame.
* The TCM stores DTC P1915 in TCM history.

Conditions for Clearing the DTC

* The ECM turns OFF the MIL after the third consecutive drive trip in which the TCM does not send a MIL illumination request.
* A scan tool can clear the DTC.
* The TCM clears the DTC from TCM history if the vehicle completes 40 warm-up cycles without a non emission related diagnostic fault occurring.
* The TCM cancels the DTC default actions when the ignition 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. All HI values, in both Park and Drive 4, indicate the ground circuit is OPEN.
5. With the transmission 20-way connector disconnected, all IMS values should indicate HI.
7. If one circuit affects the other, this indicates a short between the two circuits.
13. This step tests the internal transmission harness. If no fault is found in the harness, the fault will be in the switch.

Step 1 - Step 5:

Step 6 - Step 10:

Step 11 - Step 17: