P1825
DTC P1825
Circuit Description
The transmission manual shift shaft switch assembly is a sliding contact switch attached to the control valve body within the transmission. The 4 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 4 IMS input parameters represented are Signal A, Signal B, Signal C and Signal P (Parity).
If the TCM detects an invalid IMS range, DTC P1825 sets. DTC P1825 is a type B DTC.
DTC Descriptor
This diagnostic procedure supports the following DTC:
DTC P1825 Internal Mode Switch - Invalid Range
Conditions for Running the DTC
The engine run time is greater than 5 seconds.
Conditions for Setting the DTC
The TCM detects an invalid switch range for 5 seconds.
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 freezes transmission adaptive functions.
* The TCM assumes a D5 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 P1825 in TCM history.
Conditions for Clearing the DTC
* The ECM turns OFF the MIL after the sixth 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. This step tests the transmission manual shift shaft switch assembly for an open ground circuit.
5. This step tests for correct reference voltage from the TCM.
Step 1 - Step 6:
Step 7 - Step 17:
