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For 1990-2009 cars only

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

--