P1822

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 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 displayed are Input A, Input B, Input C and Input P (Parity).

If the PCM detects a high voltage input from circuit 772 (YEL) when the transmission selector lever is moved from PARK to D2 or D1, then DTC P1822 sets. DTC P1822 is a Type D 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 IMS B Input is continuously high this ignition cycle, and the following conditions occur:

^ The IMS indicates PARK for 4 seconds, then;

^ The IMS indicates transitional position D2-D1, and;

^ Engine torque is 95-407 N.m (70-300 lb ft) with no engine torque defaults for 6 seconds.

Action Taken When the DTC Sets

^ The PCM does not illuminate the malfunction indicator lamp (MIL).

^ The PCM stores DTC P1822 in PCM history.

Conditions for Clearing the DTC

^ A scan tool can clear the DTC from the PCM history. The PCM clears the DTC from the PCM history if the vehicle completes 40 warm-up cycles without a failure reported.

^ The PCM cancels the DTC default actions when the fault no longer exists and the ignition is OFF long enough in order to power down the PCM

Diagnostic Aids

^ Inspect the wiring for faulty electrical connections at the PCM, the transmission 20-way connector, the MS connector and all other circuit connecting points for the following conditions:

- A backed out terminal

- A damaged terminal

- Reduced terminal tension

- A chafed wire

- A broken wire inside the insulation

- Moisture intrusion

- Corrosion

^ When diagnosing for an intermittent short or open, massage the wiring harness while watching the test equipment for a change.

Test Description

The numbers below refer to the step numbers on the diagnostic table.

3. This step determines if the fault is internal or external to the transmission.

4. This step determines if the engine wiring harness circuit is at fault or the PCM.

5. This step determines if the automatic transmission wiring harness assembly is at fault or the IMS.

6. Because of harsh conditions inside the transmission, repairing the automatic transmission (A/T) wiring harness assembly is not acceptable. It must be replaced if it is damaged in any way.