P1825

Diagnostic Chart 1 Of 3:

Diagnostic Chart 2 Of 3:

Diagnostic Chart 3 Of 3:

Schematic:

CIRCUIT DESCRIPTION
The transmission internal mode switch (IMS) is a sliding contact switch attached to the selector detent inside the transmission side cover. The tour inputs to the PCM from the IMS 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 level at the PCM is high (B+) when the IMS is open and low when the switch is closed to ground. The state of each input is available for display on the scan tool. The four input parameters represented are Signals A, B, C and P (Parity).

If the PCM detects an invalid transmission range for 5 seconds with the engine running, then DTC P1825 sets. DTC P1825 is a type C DTC.

CONDITIONS FOR RUNNING THE DTC
^ The system voltage is 9-18 volts.
^ The engine speed is at least 500 RPM for 5 seconds and not in fuel shutoff.

CONDITIONS FOR SETTING THE DTC
The PCM detects an invalid combination of IMS signals for 0.5 seconds.

ACTION TAKEN WHEN THE DTC SETS
^ The PCM does not illuminate the malfunction indicator lamp (MIL).
^ The PCM records the operating conditions when the Conditions for Setting the DTC are met. The PCM stores this information as Failure Records.
^ The PCM stores DTC P1825 in PCM history.

CONDITIONS FOR CLEARING THE DTC
^ A scan tool can clear the DTC.
^ The PCM clears the DTC from PCM history if the vehicle completes 40 consecutive warm-up cycles without a non-emission-related diagnostic fault occurring.
^ The PCM cancels the DTC default actions when the fault no longer exists and the ignition switch is OFF long enough in order to power down the PCM.

DIAGNOSTIC AIDS
^ Inspect the connectors at the controller, the component and all other circuit connecting points for an intermittent condition. Refer to Testing for Intermittent and Poor Connections in Diagrams.
^ Inspect the circuit wiring for an intermittent condition. Refer to Testing for Electrical Intermittents in Diagrams.
^ Refer to the Transmission Internal Mode Switch Logic table for the normal range signals and the invalid combinations.

TEST DESCRIPTION
The numbers below refer to the step numbers on the diagnostic table.
3. HI values for all signals in all ranges indicates the ground circuit is OPEN.
6. 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.