For 1990-2009 cars

### Circuit Description

A normal function of the transmission control module (TCM) is to perform an internal test that verifies the integrity of the RAM and ROM memory allocations. When the TCM detects that the calculated EEPROM checksum is different from the stored EEPROM checksum, DTC P0601 sets. DTC P0601 is a type B DTC.

### Condition For Running The DTC

The ignition is ON for 2 seconds.

### Condition For Setting The DTC

The TCM EEPROM checksums do not match.

### Action Taken When the DTC Sets

• | The TCM flashes the sport mode lamp and sends a MIL request to the ECM on the second consecutive drive trip that the diagnostic runs and fails. The ECM then illuminates the MIL.

• | The ECM records the operating conditions in the Freeze Frame at the time of the MIL request from the TCM.

• | The transmission operates in the default mode (maximum line pressure, command 4th gear, inhibit TCC, freeze shift adapts).

### Conditions For Clearing the MIL/DTC

• | The ECM turns off the MIL after three consecutive drive trips during which the TCM sends no MIL request.

• | A History DTC clears after forty consecutive warm-up cycles, if no failures are present by this diagnostic or any other emission related diagnostic.

• | The scan tool clears the MIL/DTC.

• | The TCM cancels the DTC default mode actions when the ignition switch is Off long enough in order to power down the TCM.

### Test Description

The number below refers to the step number on the diagnostic table.

1. This step verifies that an external anomaly, such as Electromagnetic Interference (EMI), did not take place during TCM power up.

Step | Action | Value(s) | Yes | No
--- | --- | --- | --- | ---
1 | Did you perform Powertrain On Board Diagnostic (OBD) System Check - Automatic Transmission ? | -- | Go to Step 2 | Go to Powertrain On Board Diagnostic (OBD) System Check - Automatic Transmission
2 |

1. Install a Scan Tool .
2. Turn ON the ignition with the engine OFF.

Important: Record the Failure Records before clearing the DTCs. Using the Clear Info function erases the Failure Records from the ECM and the TCM.

3. Record the DTC Failure Records.
4. Clear the DTC.
5. Turn OFF the ignition for at least 30 seconds.
6. Turn ON the ignition with the engine OFF for at least 2 seconds.

Did DTC P0601 reset?

--

Go to Step 3

Go to Diagnostic Aids

3 | Caution: When you are performing service on or near the SIR components or the SIR wiring, you must disable the SIR system. Refer to Disabling the SIR System. Failure to follow the correct procedure could cause air bag deployment, personal injury, or unnecessary SIR system repairs.

Perform the Transmission Control Module Replacement procedure.

Is the action complete?

--

Go to Step 4

--

4 | Perform the following procedure in order to verify the repair:

1. Select DTC.
2. Select Clear Info.
3. Turn OFF the ignition for at least 30 seconds.
4. Turn ON the ignition with the engine OFF for at least 2 seconds.

Did DTC P0601 reset?

--

Go to Step 2

System OK