P1810

TFP Manual Valve Position Switch Logic:

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 a transmission fluid temperature (TFT) sensor combined into one unit. The combined unit mounts on the valve body.

The powertrain control module (PCM) supplies the battery voltage for each range signal. By grounding one or more of the circuits through various combinations of the pressure switches, the PCM detects which manual valve position you select. The PCM compares the actual voltage combination of the switches to a TFP manual valve position switch combination table stored in memory.

The TFP manual valve position switch cannot distinguish between PARK and NEUTRAL because the monitored valve body pressures are identical. With the engine OFF and the ignition switch in the RUN position, the TFP manual valve position switch indicates PARK or NEUTRAL. Disconnecting the transmission 20-way connector removes the ground potential for the three range signals to the PCM. In this case, with the engine OFF, and the ignition switch in the RUN position, D2 will be indicated.

When the PCM detects an invalid state of the TFP manual valve position switch or the TFP manual valve position switch circuit by deciphering the TFP manual valve position switch inputs, then DTC P1810 sets. DTC P1810 is a type B DTC.

Conditions for Running the DTC

^ No VSS assembly DTCs P0502 or P0503.
^ The system voltage is 9-18 volts.
^ The engine speed is greater than 450 RPM for 5 seconds.
^ The engine is not in fuel cutoff.
^ The engine torque is 50-450 lb ft.
^ The engine vacuum is 0-105 kPa.

Conditions for Setting the DTC

DTC P1810 sets if any of the following conditions occurs:

Condition 1

The PCM detects an illegal TFP manual valve position switch state for 60 seconds.

Condition 2
^ The engine speed is less than 100 RPM for 0.1 second; then
the engine speed is 100-600 RPM for 0.05 second; then
the engine speed is greater than 600 RPM.
^ The vehicle speed is less than 3 km/h (2 mph).
^ The PCM detects a gear range of D2, D4 or REVERSE during an engine start.
^ All conditions are met for 5 seconds

Condition 3
^ The TP angle is 7-50%.
^ The PCM commands fourth gear.
^ The Torque Converter Clutch (TCC) is locked ON.
^ The speed ratio is 0.65-0.75 (speed ratio is the engine speed divided by transmission output speed).
^ The PCM detects a gear range is PARK or NEUTRAL when operating in D4.
^ All conditions are met for 10 seconds

Action Taken When the DTC Sets

^ The PCM illuminates the malfunction indicator lamp (MIL) during the second consecutive trip in which the conditions for setting the DTC are met.
^ The PCM commands D2 line pressure.
^ The PCM commands a D4 shift pattern.
^ The PCM freezes shift adapts from being updated.
^ The PCM stores DTC P1810 in PCM history during the second consecutive trip in which the conditions for setting the DTC are met.

Conditions for Clearing the MIL/DTC

^ The PCM turns OFF the MIL during the third consecutive trip in which the diagnostic test runs and passes.
^ A scan tool clears the DTC from PCM history.
^ The PCM clears the DTC from PCM history if the vehicle completes 40 warm-up cycles without an 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

^ Refer to the TFP Manual Valve Position Switch Logic table for the normal range signals and the illegal combinations. In the table, ON is 0 volts, OFF is 12 volts.
^ Inspect the wiring at the PCM, the transmission 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 condition, massage the wiring harness while watching the test equipment for a change.
^ Refer to the TFP Manual Valve Position Switch Resistance Check or the Functional Test Procedure for in Automatic Transmissions further information.

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 actually selected.
4. This step tests for correct voltage from the PCM to the transmission 20-way connector.