For 1990-2009 cars

## DTC P0604 Non-Europe or N. American Emissions

### Circuit Description

A normal function of the transmission control module (TCM) programming is to perform an internal check that verifies the integrity of the random access memory (RAM) memory allocations.

The DTC P0604 sets when the RAM is not operating correctly when checked on initialization. An area of RAM is failed a read/write test.

### DTC Descriptor

This diagnostic procedure supports the following DTC:

DTC P0604 Transmission Control Module (TCM) Random Access Memory (RAM)

### Conditions for Setting the DTC

• | An area of RAM has failed a read/write test.

• | System voltage is too high or too low.

• | Transaxle input voltage is too high or too low.

• | Immediately after the above condition occurs

### Action Taken When the DTC Sets

• | 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 pressure control solenoid (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 P0604 sets, the replacement of TCM is recommended.

#### DTC P0604

Step | Action | 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.

Does the scan tool display P0604?

Go to Step 3

Go to Diagnostic Aids

3 |

1. Turn the ignition OFF.
2. Replace the transmission control module (TCM). Refer to Transmission Control Module Replacement .

Is the replacement complete?

Go to Step 4

--

4 |

1. Using the scan tool, clear the DTCs.
2. Road test the vehicle within the Conditions for Setting this DTC, as specified in the text.

Does the scan tool indicate that this diagnostic has run and passed?

Go to Step 5

Go to Step 2

5 | 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 P0604 European and N. American Emissions

### Circuit Description

A normal function of the transmission control module (TCM) programming is to perform an internal check that verifies the integrity of the random access memory (RAM) memory allocations.

The DTC P0604 sets when the RAM is not operating correctly when checked on initialization. An area of RAM is failed a read/write test.

### DTC Descriptor

This diagnostic procedure supports the following DTC:

DTC P0604 Transmission Control Module (TCM) Random Access Memory (RAM)

### Conditions for Setting the DTC

• | An area of RAM has failed a read/write test.

• | System voltage is too high or too low.

• | Transaxle input voltage is too high or too low.

• | 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 pressure control solenoid (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 P0604 sets, the replacement of TCM is recommended.

#### DTC P0604

Step | Action | 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.

Does the scan tool display P0604?

Go to Step 3

Go to Diagnostic Aids

3 |

1. Turn the ignition OFF.
2. Replace the transmission control module (TCM). Refer to Transmission Control Module Replacement .

Is the replacement complete?

Go to Step 4

--

4 |

1. Using the scan tool, clear the DTCs.
2. Road test the vehicle within the Conditions for Setting this DTC, as specified in the text.

Does the scan tool indicate that this diagnostic has run and passed?

Go to Step 5

Go to Step 2

5 | 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