P1810

Diagnostic Chart:

Wiring Diagram:

Circuit Description

The Automatic Transmission Fluid Pressure (TFP) Manual Valve Position Switch consists of five pressure switches (two normally-closed and three normally-open), and an automatic transmission fluid temperature (TFT) sensor. The combined unit mounts on the valve body. The PCM supplies battery voltage to each range signal. The PCM grounds one or more of the range signal circuits through various combinations of the pressure switches. The PCM monitors the combinations, in order to detect what manual valve position has been selected. The PCM compares the actual voltage combination of the switches to a TFP Valve Position Switch combination chart stored in the memory.

The TFP Valve Position Switch cannot distinguish Park from Neutral because the monitored valve body pressures are identical. With the ignition ON and the engine OFF, the valve pressures indicate Park or Neutral. Disconnecting the transmission 20 way connector, removes the ground potential for the three range signals to the PCM. This disconnected state, with the ignition ON, displays as D2.

If the PCM detects an invalid state of the TFP Valve Position Switch or the TFP Val. Position Sw. circuit, in two consecutive ignition cycles, then DTC P1810 sets. The PCM deciphers the TFP Val. Position Sw. inputs DTC P1810 is a type B DTC.

Conditions for Setting the DTC
DTC P1810 sets if any of the following Cases occurs:

Case 1
- (This set of conditions detects an illegal switch combination).
- The system voltage is 10-16 volts.
- The engine speed is greater than 400 RPM and not in fuel cut off for 5 seconds.
- The PCM detects an illegal TFP state.
- All conditions are satisfied for 60 seconds.

Case 2
- (This set of conditions detects D2, D4, or Rev during an engine start).
- No Vehicle Speed Sensor (VSS) DTCs P0502 or P0503.
- The system voltage is 10-16 volts.
- The engine speed is less than 100 RPM for 0.1 seconds; then
- The engine speed is 100-600 RPM for 0.05 seconds; then
- The engine speed is greater than 600 RPM.
- The vehicle speed is less than 3 km/h (2 mph).
- The detected gear range is D2, D4, or Rev.
- All conditions satisfied for 5 seconds.

Case3
- The engine speed is greater than 400 for 5 seconds and not in fuel cut off.
- the system voltage is 10-16 volts.
- The PCM commands Fourth gear.
- The speed ratio is 0.65-0.75 (Speed ratio is engine speed + output speed).
- The TP angle is 7-50%.
- The engine torque is 68-610 Nm (50-450 lb. ft.).
- The engine vacuum is 0-105 kPa.
- The TCC is locked on.
- No VSS DTCs P0502 or P0503.
- All conditions are met for 10 seconds.

Action Taken When the DTC Sets
- The PCM commands D2 line pressure.
- The PCM commands a D4 shift pattern.
- The PCM freezes shift adapts from being updated.
- The PCM illuminates the Malfunction Indicator Lamp (MIL).

Conditions for Clearing the MIL/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 TFP Valve Position Switch Logic Table for the normal range signals and the illegal combinations.
- Inspect the wiring for any poor electrical connections at the PCM. Inspect the wiring at the transmission 20-way connector. Look for the following problems:
- 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 an open, massage the wiring harness while watching the test equipment for changes.

Test Description

The numbers below refer to the step numbers on the diagnostic chart.
3. This step compares the indicated range signal to the manual valve you actually select.
4. This step verifies that the transmission 20 way connector receives the correct voltage from the PCM.