For 1990-2009 cars
Engine Controls Components
Cell 20: Power and Ground
OBD II Symbol Description Notice
Handling ESD Sensitive Parts Notice

### Circuit Description

Battery voltage is supplied to the PCM for the retention of certain long term memory data. Diagnostic trouble codes (DTC) 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.

### Conditions for Setting the DTC

• | No back-up power supply to the PCM after starting the engine.

• | Condition is present for 5 seconds.

### Action Taken When the DTC Sets

• | The PCM illuminates the malfunction indicator lamp (MIL).

• | The PCM stores a DTC P1510 as long as the ignition is not turned OFF.

### Conditions for Clearing the MIL/DTC

• | The MIL turns OFF after three consecutively passing trips without a fault present.

• | A History DTC clears after 40 consecutive warm-up cycles without a fault.

• | Use the scan tool Clear DTC Information function or disconnect the PCM battery feed in order to clear the DTC.

### 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 its memory of a DTC P1510 and a DTC P1510 will not be stored.

Check for a blown fuse. Replace any blown fuses and retest.

An intermittent malfunction may be caused by a problem in the memory power input circuit. Inspect the wiring harness and components for any of the following conditions:

• | Backed out terminals.

• | Improper mating of terminals.

• | Broken electrical connector locks.

• | Improperly formed or damaged terminals.

• | Faulty terminal to wire connections.

• | Physical damage to the wiring harness.

• | A broken wire inside the insulation.

• | Corrosion of electrical connections, splices, or terminals.

### Test Description

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

1. The Powertrain (OBD) System Check 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 a 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
--- | --- | --- | --- | ---
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. Start the engine.
2. Run the engine for at least 1 minute.
3. Disconnect the IAT sensor electrical connector.
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 electrical 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 faulty electrical connection at the PCM.
2. Repair as necessary.

Was a repair necessary?

--

Go to Step 7

Go to Step 6

6 | Replace the PCM. Refer to Powertrain Control Module Replacement . Is the action complete? | -- | Go to Step 7 | --
7 |

1. Perform the scan tool Clear DTC Information function and road test the vehicle within the Freeze Frame conditions that set the DTC.
2. Review scan tool data and check for DTCs. The repair is complete if no DTCs are stored.

Are any DTCs displayed on the scan tool?

--

Go to the Applicable DTC Table

System OK