For 1990-2009 cars

## DTC P0604 Non European or N. American Emissions

### DTC Descriptor

This diagnostic procedure supports the following DTC:

DTC P0604 Control Module Random Access Memory (RAM)

### Conditions for Setting the DTC

• | The transmission control module (TCM) cannot carry out the 4 random access memory (RAM) initialization routines.

• | The TCM detects that the RAM cannot be written and read correctly.

### Action Taken When the DTC Sets

The TCM will request the illumination of the hold lamp and store the DTC when the TCM detects failures on 2 consecutive ignition cycles.

### Conditions for Clearing the DTC

• | The TCM turns OFF the hold lamp when no further failures are detected on the next ignition cycles.

• | The scan tool can clear the DTC from the TCM history.

• | The TCM clears the DTC from the TCM history memory after 40 consecutive ignition cycles without fault.

### Cause of Failure

• | The harness or connector between the TCM and the engine control module (ECM)

• | The ECM

• | The TCM

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

1. Turn OFF the ignition.
2. Install the scan tool.
3. With the engine OFF, turn the ignition switch to the ON position.
4. Select Store Freeze Frame/Failure Records from the DTC Information menu.
5. Store Freeze Frame/Failure Records.
6. Select Clear DTC Information from the DTC Information menu.
7. Clear DTC Information.
8. Perform 2 vehicle drive cycles.

Is the hold lamp ON?

Go to Step 3

Go to Step 4

3 |

1. Select Request DTC by Status from the DTC Information menu.
2. Request DTC by Status.

Is DTC P0604 displayed?

Go to Step 5

Go to Step 4

4 | Inspect the transmission control module (TCM) wiring harness and connector for signs of an intermittent condition. Repair as necessary. Did you complete the action? | System OK | --
5 | Replace the TCM. Refer to Transmission Control Module Replacement . Did you complete the replacement? | System OK | --

## DTC P0604 European and N. American Emissions

### DTC Descriptor

This diagnostic procedure supports the following DTC:

DTC P0604 Control Module Random Access Memory (RAM)

### Conditions for Setting the DTC

• | The transmission control module (TCM) cannot carry out the 4 random access memory (RAM) initialization routines.

• | The TCM detects that the RAM cannot be written and read correctly.

### Action Taken When the DTC Sets

The TCM will request the illumination of the malfunction indicator lamp (MIL) and store the DTC when the TCM detects failures on 2 consecutive ignition cycles.

### Conditions for Clearing the DTC

• | The TCM turns off the MIL when no further failures are detected on the next ignition cycles.

• | The scan tool can clear the DTC from the TCM history.

• | The TCM clears the DTC from the TCM history memory after 40 consecutive ignition cycles without fault.

### Cause of Failure

• | The harness or connector between the TCM and the engine control module (ECM)

• | The ECM

• | The TCM

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

1. Turn OFF the ignition.
2. Install the scan tool.
3. With the engine OFF, turn the ignition switch to the ON position.
4. Select Store Freeze Frame/Failure Records from the DTC Information menu.
5. Store Freeze Frame/Failure Records.
6. Select Clear DTC Information from the DTC Information menu.
7. Clear DTC Information.
8. Perform 2 vehicle drive cycles.

Is the malfunction indicator lamp (MIL) ON?

Go to Step 3

Go to Step 4

3 |

1. Select Request DTC by Status from the DTC Information menu.
2. Request DTC by Status.

Is DTC P0604 displayed?

Go to Step 5

Go to Step 4

4 | Inspect the transmission control module (TCM) wiring harness and connector for signs of an intermittent condition. Repair as necessary. Did you complete the action? | System OK | --
5 | Replace the TCM. Refer to Transmission Control Module Replacement . Did you complete the replacement? | System OK | --