For 1990-2009 cars

## DTC P1840 Non-Europeor N. American Emissions

### Circuit Description

The pressure control valves (PCS) 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 the electrical pressure regulating valves are supplied. As a result, smaller solenoid valves may be used. The PCS requires a constant input pressure.

### Conditions for Setting the DTC

• | Output voltage of the PCS 3, at ON, is 12 volts.

• | No DTC P1839, P1841.

• | 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.

• | After ignition OFF/ON: 3rd gear by hydraulic control. P, R and N also possible.

• | Power supply cut off to the PCS 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 P1840 sets, the possible cause of the fault could be the PCS 3 valve.

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. Select Actuating on the scan tool.
4. Actuate the pressure control valves (PCS) 3 ON/OFF.

Does the PCS 3 change ON/OFF?

--

Go to Diagnostic Aids

Go to Step 3

3 |

1. Remove the oil pan.
2. Disconnect the wiring connector of the PCS 3.
3. Turn the ignition ON, with the engine OFF.
4. Measure the voltage of the PCS 3 wiring connector terminal 1.

Is the voltage within the specified value?

11-14 V

Go to Step 4

Go to Step 5

4 | Repair the internal line PCS 3 for a short to power. Is the repair complete? | -- | System OK | --
5 | Replace the PCS 3. Is the replacement complete? | -- | Go to Step 6 | --
6 | Inspect if any DTCs are set. Are any DTCs displayed that have not been diagnosed? | -- | Go to Diagnostic Trouble Code (DTC) List - Vehicle | System OK

## DTC P1840 European and N. American Emissions

### Circuit Description

The pressure control valves (PCS) 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 the electrical pressure regulating valves are supplied. As a result, smaller solenoid valves may be used. The PCS requires a constant input pressure.

### Conditions for Setting the DTC

• | Output voltage of the PCS 3 (at ON) is 12 volts.

• | No DTC P1839, P1841.

• | Immediately after the above condition occurs

### Action Taken When the DTC Sets

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

• | The 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.

• | After ignition OFF/ON : 3rd gear by hydraulic control. P, R, and N also possible.

• | Power supply cut off to the PCS 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 P1840 sets, the possible cause of the fault could be the PCS 3 valve.

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. Select Actuating on the scan tool.
4. Actuate the pressure control valves (PCS) 3 ON/OFF.

Does the PCS 3 change ON/OFF?

--

Go to Diagnostic Aids

Go to Step 3

3 |

1. Remove the oil pan.
2. Disconnect the wiring connector of the PCS 3.
3. Turn the ignition ON, with the engine OFF.
4. Measure the voltage of the PCS 3 wiring connector terminal 1.

Is the voltage within the specified value?

11-14 V

Go to Step 4

Go to Step 5

4 | Repair the internal line PCS 3 for a short to power. Is the repair complete? | -- | System OK | --
5 | Replace the PCS 3. Is the replacement complete? | -- | Go to Step 6 | --
6 | Inspect if any DTCs are set. Are any DTCs displayed that have not been diagnosed? | -- | Go to Diagnostic Trouble Code (DTC) List - Vehicle | System OK