GM Service Manual Online
For 1990-2009 cars only

Circuit Description

The DTC P1510 Control Module Long Term Memory Reset monitors the battery voltage supply to the PCM. The battery voltage is supplied to the powertrain control module (PCM) for the retention of certain long term memory data. Diagnostic trouble codes and learned engine control parameters are kept in the PCM memory even when the ignition is Off. A DTC P1510 sets and the PCM long term memory information is lost when the memory power input circuit voltage is interrupted.

Condition for Running the DTC

The engine is running.

Conditions for Setting the DTC

    • No back-up power is supplied to the PCM after starting the engine.
    • The condition is present for 5 seconds.

Action Taken When the DTC Sets

    • The PCM illuminates the malfunction indicator lamp (MIL).
    • The PCM stores DTC P1510 as long as the ignition is not turned OFF.

Conditions for Clearing the MIL/DTC

    • The MIL turns off after 3 consecutively passing trips without a fault present.
    • A history DTC clears after 40 consecutive warm-up cycles without a fault.
    • Perform the scan tool Clear DTC Information function.

Diagnostic Aids

The PCM will indicate a DTC P1510 as long as the ignition is On. As soon as the ignition is turned Off the PCM will lose memory of DTC P1510 and DTC P1510 will not be stored.

Check for an open fuse. Replace any open fuses and retest.

If the DTC P1510 is intermittent, driving the vehicle under the following conditions can verify whether the fault is present. Perform the scan tool Clear DTC Information function. Road test the vehicle while monitoring the DTC P1510 diagnostic on the scan tool under the Not Ran Since Code Cleared selection in the DTC Information menu. If DTC P1510 appears in the Not Ran Since Code Cleared list, the P1510 diagnostic has not yet run. When DTC P1510 does not appear in the Not Ran Since Code Cleared list, the P1510 diagnostic has run. If the MIL is NOT illuminated and there is no Pending DTC Status in DTC Information, the P1510 diagnostic has passed. The DTCs MUST be cleared in order to view the Current Status of the Not Ran Since Code Cleared list. DO NOT forget that the Not Ran Since Code Cleared list only indicates that the test has run, not whether the test passed or failed. The DTC Information screen must be checked for Current or Pending status in order to determine the outcome of the diagnostic test involved.

An intermittent malfunction may be caused by a problem in the memory power input circuit. Inspect the wiring harness and components for an intermittent condition. Refer to Intermittent Conditions .

Test Description

The numbers below refer to the step numbers in the diagnostic table.

  1. The Diagnostic System Check-Engine Controls prompts the technician to complete some basic checks and store the Freeze Frame data on the scan tool if applicable. This creates an electronic copy of the data taken when the fault occurred. The information is then stored in the scan tool for later reference.

  2. This step determines if the fault is present.

  3. This step checks for voltage at the PCM when the ignition is OFF. The PCM should indicate battery voltage on this terminal under all operating conditions.

Step

Action

Value(s)

Yes

No

Schematic Reference: Engine Controls Schematics

1

Did you perform the Diagnostic System Check-Engine Controls?

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Go to Step 2

Go to Diagnostic System Check - Engine Controls

2

  1. Start the engine.
  2. Disconnect the IAT sensor electrical connector.
  3. Run the engine for at least 1 minute.
  4. Observe that the MIL is illuminated.
  5. Connect the IAT sensor electrical connector.
  6. Turn OFF the ignition.
  7. Wait for at least 1 minute.
  8. Turn ON the ignition, leaving the engine OFF.
  9. Check for DTCs with a scan tool.

Is a DTC P0113 indicated?

--

Go to Diagnostic Aids

Go to Step 3

3

  1. Turn OFF the ignition.
  2. Disconnect the PCM connectors.
  3. Measure the voltage from the memory power circuit to ground using a DMM.

Is the voltage near the specified value?

B+

Go to Step 5

Go to Step 4

4

  1. Check the memory power circuit for an open or a short between the PCM and the fuse block 2.
  2. Repair as necessary. Refer to Wiring Repairs in Wiring Systems.

Was a repair necessary?

--

Go to Step 7

Go to Diagnostic Aids

5

  1. Check for a poor connection at the PCM.
  2. Repair as necessary. Refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems.

Was a repair necessary?

--

Go to Step 7

Go to Step 6

6

Replace the PCM. Refer to Powertrain Control Module Replacement .

Did you complete the replacement?

--

Go to Step 7

--

7

  1. Use the scan tool in order to clear the DTCs.
  2. Turn OFF the ignition for 30 seconds.
  3. Start the engine.
  4. Operate the vehicle within the Conditions for Running the DTC as specified in the supporting text.

Does the DTC run and pass?

--

Go to Step 8

Go to Step 2

8

With the scan tool, observe the stored information, Capture Info.

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

--

Go to Diagnostic Trouble Code (DTC) List

System OK