GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 GMC_Truck 🢒 1999 🢒 Sonoma Pickup - 2WD 🢒 DTC 🢒 DTC P0601 Control Module Read Only Memory (ROM)

Circuit Description

The PCM uses an Electrically Erasable Programmable Read Only Memory (EEPROM) to house the program information and the calibrations required for the engine, the transmission, and the powertrain diagnostics operation. The PCM uses a value called a checksum for error detection of the software. The checksum is a value that is equal to all the numbers in the software added together. The PCM adds all the values in the software. If that value does not equal the checksum value, a checksum error is indicated.

Conditions for Setting the DTC

The PCM detects more than 3 incorrect checksums.

Action Taken When the DTC Sets
    • The Malfunction Indicator Lamp (MIL) illuminates.
    • The PCM attempts to record the operating conditions at the time this failure is detected; however, since this is an internal PCM failure, this information may or may not be reliable. The Freeze Frame and Failure Records buffers store this information.
    • A history DTC is stored.

Conditions for Clearing the MIL/DTC
    • The malfunction indicator lamp (MIL) will turn OFF after 3 consecutive ignition cycles in which the diagnostic runs without a fault.
    • A history DTC will clear after 40 consecutive warm up cycles without a fault.
    • Use a scan tool to clear the DTCs.

Test Description

The numbers below refer to the step numbers on the Diagnostic Table.

  1. The Powertrain OBD System Check prompts you to complete some of the basic checks and to store the freeze frame and failure records data on the scan tool if applicable. This creates an electronic copy of the data captured when the malfunction occurred. The scan tool stores this data for later reference.

    2.

  2. Program the replacement PCM and perform the Crankshaft Position System Variation Learn Procedure. Refer to the latest Techline procedures for PCM programming.

DTC P0601-PCM Memory

Step

Action

Value(s)

Yes

No

1

Did you perform the Powertrain On-Board Diagnostic (OBD) System Check?

--

Go to Step 2

Go to Powertrain On Board Diagnostic (OBD) System Check

2

  1. Turn OFF the ignition.
  2. Replace the PCM. Refer to Powertrain Control Module Replacement/Programming .

Is the action complete?

--

Go to Step 3

--

3
  1. Using the scan tool, clear the DTCs.
  2. Start the engine.
  3. Idle the engine at the normal operating temperature.
  4. Operate the vehicle within the Conditions for setting this DTC as specified in the supporting text.

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

--

Go to Step 4

Go to Step 2

4

Check to see if any additional DTCs are set.

Does the scan tool display any DTCs that you have not diagnosed?

--

Go to the applicable DTC table

System OK