P1810

Diagnostic Chart:

Diagnostic Chart (cont'd):

Wiring Diagram:

Circuit Description
The Transmission Fluid Pressure Valve Position Switch (TFP Val. Position Sw.) consists of five normally-open pressure switches. The PCM supplies battery voltage to each range signal. By grounding one or more of these circuits through various combinations of the pressure switches, the PCM detects what manual valve position has been selected and compares the actual voltage combination of the switches to a TFP Val. Position Sw. combination table stored in memory.

The TFP Val. Position Sw. cannot distinguish between Park and Neutral because the monitored valve body pressures are identical in both cases. With the ignition On and the engine Off, D2 is indicated. When the transmission 20-way connector is disconnected, the ground potential for the three range signals to the PCM is removed, and with the ignition On, D2 is indicated.

When the PCM detects an invalid state of the TFP Val. Position Sw. circuit by deciphering the TFP Val Position Sw. inputs, then DTC P1810 sets. DTC P1810 is a type A DTC.

Conditions for Setting the DTC
DTC P1810 sets if any of the following conditions occur:

Condition 1

^ No system voltage DTC P0560.
^ The engine is running.
^ The PCM detects an illegal TFP Val. Position Sw. combination for greater than 25 seconds.

Condition 2

^ No system voltage DTC P0560.
^ No OSS Sensor DTCs P0722 or P0723.
^ The engine speed is less than 50 RPM for 0.5 seconds, 50-525 RPM for greater than 0.1 seconds and then the engine speed is greater than 525 RPM and the vehicle speed is less than 3 km/h (2 mph).
^ The PCM detects the gear range as D2 before and after start up.
^ The condition exists for greater than 7 seconds. The PCM looks for a condition change only at start-up.

Condition 3

^ No Accelerator Pedal Position (APP) Sensor DTCs P0121, P0122, P0123, P0220, P0221, P0222, P0223, P0225, P0226, P0227, or P0228.
^ No Input Speed Sensor (ISS) Sensor DTCs P0716 or P0717.
^ No Output Speed (OSS) DTCs P0722 or P0723.
^ No 1-2 SS Valve DTCs P0751 or P0753.
^ No 2-3 SS Valve DTCs P0756 or P0758.
^ The engine speed is less than 37-50 RPM.
^ The vehicle speed is greater than 8 km/h (5 mph).
^ The Throttle Position (TP) Sensor is greater than 12%.
^ The engine torque is 100-565 Nm (80-450 lb. ft).
^ The engine is running for more than 5 seconds.
^ The TFP Val. Position Sw. indicates the following:

- P/N when the ratio indicates less than 1.58:1 for greater than 10 seconds.
- Reverse when the ratio indicates D4, D3, D2, and D1 for greater than 15 seconds.
- D4, D3, D2, and D1 when the ratio indicates reverse for greater than 15 seconds.

Action Taken When the DTC Sets

^ The PCM commands maximum line pressure.
^ The PCM assumes D4 for the PRNDL shift pattern.
^ The PCM freezes shift adapts.
^ The PCM illuminates the Malfunction Indicator Lamp (MIL).

Conditions for Clearing the DTC

^ The PCM turns OFF the MIL after three consecutive ignition cycles without a failure reported.
^ 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

^ Refer to the accompanying table for the normal range signals and the illegal combinations.
^ Inspect the wiring for poor electrical connections at the PCM Inspect the wiring for poor electrical connections at the transmission 20-way connector. Look for the following conditions:

- A bent terminal
- A backed out terminal
- A damaged terminal
- Poor terminal tension
- A chafed wire
- A broken wire inside the insulation

^ When diagnosing for an intermittent short or open condition, massage the wiring harness while watching the test equipment for a change.
^ DTC P1810 can be falsely set during a fluid fill procedure. After refilling the fluid, cycle key down then start and run the vehicle for 20 seconds. Key down and allow the PCM to power down, and then restart the vehicle.
^ DTC P1810 can be set falsely by low pump pressure or a stuck pressure regulator.
^ DTC P1810 can be set by a slipping forward clutch assembly. It may allow the PCM to see a 2.08:1 ratio (reverse) when the manual valve position is indicated as D4.
^ First diagnose and clear any engine DTCs or APP Sensor codes that are present. Then inspect for any transmission DTCs that may have reset.
^ Refer to the Range Signal table.

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

3. This step tests the indicated range signal to the manual valve that is actually selected.
4. This step tests the voltage from the PCM to the transmission 20-way connector.