This diagnostic procedure supports the following DTC:
DTC P0604 Control Module Random Access Memory (RAM)
| • | 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. | 
The TCM will request the illumination of the hold lamp and store the DTC when the TCM detects failures on 2 consecutive ignition cycles.
| • | 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. | 
| • | 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  | |
2  | 
 Is the hold lamp ON?  | Go to Step 3  | Go to Step 4  | 
3  | 
 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  | --  | 
This diagnostic procedure supports the following DTC:
DTC P0604 Control Module Random Access Memory (RAM)
| • | 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. | 
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.
| • | 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. | 
| • | 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  | |
2  | 
 Is the malfunction indicator lamp (MIL) ON?  | Go to Step 3  | Go to Step 4  | 
3  | 
 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  | --  |