For 1990-2009 cars
Engine Controls Components
Cell 21: Power and Ground
OBD II Symbol Description Notice
Handling ESD Sensitive Parts Notice

### Circuit Description

Battery voltage supplies the PCM with long term memory. Diagnostic trouble codes (DTC) and engine control parameters that were learned 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 circuit voltage in the memory power input is interrupted.

### Conditions for Setting the DTC

• | There is not a back-up power supply 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 a DTC P1510 as long as the ignition remains ON.

### Conditions for Clearing the MIL/DTC

• | The MIL turns OFF after three consecutive trips, during which the diagnostic runs and a fault is not detected.

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

• | Use the Clear DTC Information function on the scan tool, 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 memory of a DTC P1510, and a DTC P1510 will not be stored.

Check for a blown fuse. Replace any blown fuses, and retest the diagnostic.

A fault in the memory power input circuit may cause an intermittent malfunction. Inspect the wiring harness and the components for any of the following conditions:

• | Backed out terminals

• | Incorrect mating of terminals

• | Broken electrical connector locks

• | Incorrectly formed terminals or damaged terminals

• | Faulty terminal-to-wire connections

• | Physical damage to the wiring harness

• | A broken wire inside the insulation

• | Corrosion of electrical connections, of splices, or of 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 to save the applicable Freeze Frame data on the scan tool. This creates an electronic copy of the data that was taken when the fault occurred. The scan tool saves the information for later reference.

2. This step determines if a fault is present.

3. This step checks for voltage at the PCM if the ignition is off. The PCM should indicate the battery voltage on this terminal during 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. Use a scan tool in order to check for DTCs.

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. Use a DMM in order to measure the voltage from the battery positive voltage circuit to ground.

Is the voltage near the specified value?

B+

Go to Step 5

Go to Step 4

4 |

1. Check the battery positive voltage circuit for a short between the PCM and the fuse block 2.
2. Repair the circuit 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 the connection as necessary. Refer to Wiring Repairs or to Connector Repairs in Wiring Systems.

Was a repair necessary?

--

Go to Step 7

Go to Step 6

6 | Replace the PCM. Is the action complete? | -- | Go to Step 7 | --
7 |

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

Does the scan tool display any DTCs?

--

Go to the applicable DTC table

System OK