GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Holden 🢒 2005 🢒 Caprice WL 🢒 DTC 🢒 DTC P1810
Table 1: TFP Manual Valve Position Switch Logic Table

DTC Description

This diagnostic procedure covers DTC P1810--Pressure Switch Circuit.

Circuit Description

The 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 is selected.

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 ON position, the TFP manual valve position switch indicates Park/Neutral.

Disconnecting the transmission 20-way (X121-X2) 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 ON 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, which is a Type B DTC.

Conditions for Running the DTC
    • No VSS DTCs are set.
    • The system voltage is between 8.0-18.0 volts.
    • The engine speed is greater than 300 RPM for 5 seconds.
    • The engine is not in fuel cut-off.
    • The engine torque is 54-542 N·m.
    • The engine vacuum is between 0-105 kPa.

Conditions for Setting the DTCs

Condition 1

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

Condition 2

    • The engine speed is less than 80 RPM for 0.1 second, then the engine speed is 80-550 RPM for 0.07 second, then the engine speed is greater than 550 RPM.
    • The vehicle speed is less than 3 km/h.
    • The PCM detects a gear range of 2, D, or R during an engine start.
    • All conditions are met for 5 seconds.

Condition 3

    • The TP angle is between 10-50 percent.
    • The PCM commands 4th gear.
    • The TCC is locked ON.
    • The speed ratio is 0.60-0.75 (speed ratio is engine speed divided by transmission output speed).
    • The PCM detects a gear range of P or N when operating in D.
    • All conditions are met for 10 seconds.

Conditions for Clearing the DTC

The TFP Valve Position Switch Circuit DTC is a Type B DTC. Refer to Diagnostic Starting Point - Automatic Transmission for Action Taken when Type B DTCs set and Conditions for Clearing Type B DTCs.

Additional Information
    • Verify that the transmission shift pattern complies with the shift pattern charts. Refer to Diagnostic System Check - Automatic Transmission. Other internal transmission failures may cause more than one shift to occur.
    • Refer to Powertrain Control Module Description for details of the PCM operation.
    • For an intermittent fault condition, refer to Intermittent Conditions.
    • Since a fault condition in a wiring connector may trigger DTCs, always test the connectors related to this diagnostic procedure for shorted terminals or poor wiring connection before replacing any component. Refer to Testing for Intermittent Conditions and Poor Connections for information on electrical fault diagnosis.
    • Refer to Automatic Transmission Controls Schematics , Automatic Transmission Inline 20-Way Connector End View , Automatic Transmission Internal Connector End Views , Automatic Transmission Control Module Connector End Views , and Automatic Transmission Related Connector End Views to aid in the diagnosis procedures.

TFP Manual Valve Position Switch Logic Table

Gear Position

Range Signal A

Range Signal B

Range Signal C

Park

Open 12 V

Closed 0 V

Open 12 V

Reverse

Closed 0 V

Closed 0 V

Open 12 V

Neutral

Open 12 V

Closed 0 V

Open 12 V

D

Open 12 V

Closed 0 V

Closed 0 V

3

Open 12 V

Open 12 V

Closed 0 V

2

Open 12 V

Open 12 V

Open 12 V

1

Closed 0 V

Open 12 V

Open 12 V

Invalid

Closed 0 V

Open 12 V

Closed 0 V

Invalid

Closed 0 V

Closed 0 V

Closed 0 V

Test Description

The following number refers to the step number in the diagnostic chart.

5 By providing the ground for each transmission range switch circuit, the PCM should respond by changing the TR switch display from Open 12 volt to Closed 0 volt. For the circuits that do not change, an open circuit may exist.

Step

Action

Yes

No

1

Was the Main Diagnostic Table performed?

Go to Step 2

Refer to Diagnostic System Check - Automatic Transmission

2
  1. Using Tech 2, observe the Freeze Frame/Failure Records for this DTC.
  2. Switch OFF the ignition for 30 seconds.
  3. Operate the vehicle within the Conditions for Running the DTC or within the conditions in the Freeze Frame/Failure Records.
  4. Using Tech 2, select Engine/Diagnostic Trouble Codes/Read DTC Information.

Does DTC P1810 fail this ignition cycle?

Go to Step 3

Refer to Diagnostic Aids for the TFP Valve Position Switch Circuit DTCs

3

Perform the transmission fluid checking procedure.

Was any fault found and rectified?

Go to Step 10

Go to Step 4

4
  1. Start the engine.
  2. Using Tech 2, select Transmission/Data Display/Transmission Data and scroll down to TFP Switch A (Transmission Fluid Pressure), TFP Switch B (Transmission Fluid Pressure), TFP Switch C (Transmission Fluid Pressure).
  3. Observe the TFP switch displays while selecting each gear position.
  4. Compare the display at each position selected to the TFP Manual Valve Position Switch Logic table.

Does the Tech 2 display match the TFP Manual Valve Position Switch Logic table for each gear position?

Refer to Diagnostic Aids for the TFP Valve Position Switch Circuit DTCs

Go to Step 5

5
  1. Switch the ignition OFF.
  2. Disconnect connector X121-X2 from the transmission assembly.
  3. Connect a 3-amp fused jumper wire between each TFP switch signal circuit, one at a time, and a known ground.
  4. Switch the ignition ON with the engine not running.
  5. Using Tech 2 select Transmission/Data Display/Transmission Data and scroll down to TFP Switch A (Transmission Fluid Pressure), TFP Switch B (Transmission Fluid Pressure), TFP Switch C (Transmission Fluid Pressure).

Does each TFP switch display on Tech 2 change from Open 12 volts to Closed 0 volts when the respective circuit is grounded?

Go to Step 7

Go to Step 6

6

Test each TFP switch signal circuit(s) that did not change status for a high resistance, open circuit, short to ground, or short to voltage fault condition.

Was any fault found and rectified?

Go to Step 10

Go to Step 9

7

Ensure that the transmission linkage from the select lever to the manual value is adjusted correctly. Refer to Range Selector Lever Link Adjustment.

Was any fault found and rectified?

Go to Step 10

Go to Step 8

8

Important: Check for damaged wiring (short to ground, short to voltage, high resistance, or open circuit) or poor connections inside the transmission assembly before replacing the TFP switch.

Replace the TFP switch. Refer to Transmission Fluid Pressure Manual Valve Position Switch Logic.

Was the repair completed?

Go to Step 10

--

9

Replace the PCM. Refer to Powertrain Control Module Replacement.

Was the repair completed?

Go to Step 10

--

10
  1. Using Tech 2, clear the DTCs.
  2. Switch OFF the ignition for 30 seconds.
  3. Start the engine.
  4. Operate the vehicle within the conditions in the Freeze Frame/Failure Records.

Do any TFP Valve Position Switch Circuit DTCs fail this ignition cycle?

Go to Step 2

Go to Step 11

11

Using Tech 2, select the DTC Display function.

Are there any DTCs displayed?

Go to the appropriate DTC Table

System OK

When all diagnosis and repairs are completed, check the powertrain management system for correct operation.