For 1990-2009 cars

## DTC P1871 Non-Europe or N. American Emissions

### Circuit Description

The pressure control valves 3, 4, 5, and 6 are precision electronic pressure regulators that control the operation of the clutches, brakes, and lock-up clutch.

The valve reduces the system pressure with which the downstream solenoid valves and electrical pressure regulating valves are supplied. It is possible to use smaller solenoid valves as a result. The pressure control solenoid valves require a constant input pressure.

### Conditions for Setting the DTC

• | If the voltage applied to high side driver is higher than 6 volts with high side driver switch off status, then a fault is detected.

• | No DTC P1870.

• | Immediately after the above condition occurs

### Action Taken When the DTC Sets

• | The hold lamp will blink.

• | The transmission control module (TCM) will record operating conditions at the time the diagnostic fails. This information will be stored in the Failure Records buffer.

• | Adopt Emergency/Substitute mode and constant 4th gear by hydraulic control.

• | Power supply cut off to the pressure control solenoid valve.

### Conditions for Clearing the Hold Lamp/DTC

• | The hold lamp will turn OFF when the malfunction has not occurred after 3 ignition cycles.

• | A history DTC will clear after 40 consecutive warm-up cycles without a fault.

• | Using a scan tool can clear history DTCs.

### Diagnostic Aids

When DTC P1871 sets, the possible cause of the fault could be the solenoid valve power supply line.

Step | Action | Values | Yes | No
--- | --- | --- | --- | ---
1 | Did you perform the Diagnostic System Check - Vehicle? | -- | Go to Step 2 | Go to Diagnostic System Check - Vehicle
2 |

1. Install the scan tool.
2. Turn the ignition ON, with the engine OFF.
3. Start the engine and allow the engine to warm up at idle.
4. Put the gear selector in Park and set the parking brake.
5. Observe PCS 3, 4, 5, 6 input ampere and output ampere on the scan tool.

Is the amperage within the specified value?

0-2 A

Go to Diagnostic Aids

Go to Step 3

3 |

1. Turn the ignition OFF.
2. Disconnect the transaxle wiring connector and the transmission control module (TCM) connector.
3. Measure the voltage of the transaxle wiring terminal 5.

Is the voltage within the specified value?

11-14 V

Go to Step 4

Go to Step 5

4 | Repair the circuit for a short to power. Is the action complete? | -- | System OK | --
5 |

1. Remove the oil pan.
2. Disconnect the pressure control solenoid valve wiring connector.
3. Turn the ignition ON, with the engine OFF.
4. Measure the voltage of the pressure control solenoid valve 3 terminal 2.
5. Measure the voltage of the pressure control solenoid valve 4 terminal 2.
6. Measure the voltage of the pressure control solenoid valve 5 terminal 2.
7. Measure the voltage of the pressure control solenoid valve 6 terminal 2.

Is the voltage within the specified value?

11-14 V

Go to Step 6

Go to Step 7

6 | Repair the circuits for a short to power. Is the action complete? | -- | System OK | --
7 | Replace the TCM. Refer to Transmission Control Module Replacement . Is the action complete? | -- | Go to Step 8 | --
8 |

1. After the repair, use a scan tool Clear Info function and road test the vehicle.
2. Review the DTC Info.

Has the last test failed or is the current DTC displayed?

--

Go to Step 2

System OK

## DTC P1871 European and N. American Emissions

### Circuit Description

The pressure control valves 3, 4, 5, and 6 are precision electronic pressure regulators that control the operation of the clutches, brakes and lock-up clutch.

The valve reduces the system pressure with which the downstream solenoid valves and electrical pressure regulating valves are supplied. It is possible to use smaller solenoid valves as a result. The pressure control solenoid valves require a constant input pressure.

### Conditions for Setting the DTC

• | If the voltage applied to high side driver is higher than 6 volts with high side driver switch off status, then a fault is detected.

• | Immediately after the above condition occurs.

### Action Taken When the DTC Sets

• | The malfunction indicator lamp (MIL) will illuminate.

• | The transmission control module (TCM) will record operating conditions at the time the diagnostic fails. This information will be stored in the Failure Records buffer.

• | Adopt Emergency/Substitute mode and constant 4th gear by hydraulic control.

• | Power supply cut off to the pressure control solenoid valve.

### Conditions for Clearing the MIL/DTC

• | The MIL will turn OFF when the malfunction has not occurred after 3 ignition cycles.

• | A history DTC will clear after 40 consecutive warm-up cycles without a fault.

• | Using a scan tool can clear history DTCs.

### Diagnostic Aids

When DTC P1871 sets, the possible cause of the fault could be the solenoid valve power supply line.

#### DTC P1871

Step | Action | Values | Yes | No
--- | --- | --- | --- | ---
1 | Did you perform the Diagnostic System Check - Vehicle? | -- | Go to Step 2 | Go to Diagnostic System Check - Vehicle
2 |

1. Install the scan tool.
2. Turn the ignition ON, with the engine OFF.
3. Start the engine and allow the engine to warm up at idle.
4. Put the gear selector in Park and set the parking brake.
5. Observe "EDS 3,4,5,6's input ampere and output ampere" on the scan tool.

Is the amperage within the specified value?

0-2 A

Go to Diagnostic Aids

Go to Step 3

3 |

1. Turn the ignition OFF.
2. Disconnect the transaxle wiring connector and the transmission control module (TCM) connector.
3. Measure the voltage of the transaxle wiring terminal 5.

Is the voltage within the specified value?

11-14 V

Go to Step 4

Go to Step 5

4 | Repair the circuit for a short to power. Is the action complete? | -- | System OK | --
5 |

1. Remove the oil pan.
2. Disconnect the pressure control solenoid valve wiring connector.
3. Turn the ignition ON, with the engine OFF.
4. Measure the voltage of the pressure control solenoid valve 3 terminal 2.
5. Measure the voltage of the pressure control solenoid valve 4 terminal 2.
6. Measure the voltage of the pressure control solenoid valve 5 terminal 2.
7. Measure the voltage of the pressure control solenoid valve 6 terminal 2.

Is the voltage within the specified value?

11-14 V

Go to Step 6

Go to Step 7

6 | Repair the circuits for a short to power. Is the action complete? | -- | System OK | --
7 | Replace the TCM. Refer to Transmission Control Module Replacement . Is the action complete? | -- | Go to Step 8 | --
8 |

1. After the repair, use a scan tool "clear info" function and road test the vehicle.
2. Review the "DTC info".

Has the last test failed or is the current DTC displayed?

--

Go to Step 2

System OK