4T65-E Automatic Transaxle
DTC P1825
Circuit Description
The transmission internal mode switch (IMS) is a sliding contact switch attached to the selector detent inside the transmission side cover. The four inputs to the PCM indicate the position of the transmission range selector. 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 four input parameters represented are Signals A, B, C and P - Parity. Refer to Transmission Internal Mode Switch Logic.
If the PCM detects an invalid transmission range with the engine running, then DTC P1825 sets. DTC P1825 is a type C DTC.
DTC Descriptor
This diagnostic procedure supports the following DTC:
DTC P1825 Internal Mode Switch - Invalid Range
Conditions for Running the DTC
The engine speed is at least 500 RPM for 5 seconds and not in fuel cut off.
Conditions for Setting the DTC
The PCM detects an invalid combination of IMS signals for 60 seconds.
Action Taken When the DTC Sets
* The PCM does not illuminate the malfunction indicator lamp (MIL).
* The PCM commands maximum line pressure.
* The PCM freezes transmission adaptive functions.
* The PCM assumes D4 for shifting.
* 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 warm-up cycles without a non-emission-related diagnostic fault occurring.
* The PCM cancels the DTC default actions when the ignition switch is OFF long enough in order to power down the PCM.
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.
4. With the 20-way connector disconnected, all signals should indicate HI.
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.
Step 1 - Step 6:
Step 7 - Step 13:
