For 1990-2009 cars
Engine Controls Components
Cell 21: IAC Valve, Generator, TR, and Oil Switches
OBD II Symbol Description Notice
Handling ESD Sensitive Parts Notice

### Circuit Description

The Engine Oil Level Switch is a simple float switch that is grounded when the engine oil level is OK. The PCM checks the Engine Oil Level switch circuit at startup. Before checking the state of the Engine Oil Level switch, the PCM performs a test routine based on time and engine coolant temperature to ensure that the engine oil has drained back into the sump. To test for low oil level at start-up, one of the following conditions must be present:

• | The engine coolant temperature must be greater than 15°C (59°F).

• | The engine coolant temperature at key ON must be at least 12°C (22°F) cooler than the engine coolant temperature at the last key OFF.

The Low Oil Level Lamp will be illuminated for about a minute when the PCM checks for low oil level and the Engine Oil Level switch indicates that a low oil level condition exists (Engine Oil Level switch circuit not grounded). When the ignition is first turned ON, the IPC commands the Low Oil Level lamp ON for a brief period of time to test the bulb.

### Diagnostic Aids

For diagnosis of the instrument panel, perform the System Check in the Instrument Cluster section of Electrical Diagnosis.

Check for the following conditions:

• | Poor connection at PCM or oil level sensor. Inspect harness connectors for backed out terminals, improper mating, broken locks, improperly formed or damaged terminals, and poor terminal to wire connection. Refer to Intermittents and Poor Connections Diagnosis and Connector Repairs and Wiring Repairs in Wiring Systems.

• | Damaged harness. Inspect the wiring harness for damage. If the harness appears to be OK, disconnect the PCM and turn the ignition ON. Observe a voltmeter connected to the affected PCM output circuit while moving connectors and wiring harnesses related to the PCM output circuit. A change in voltage will indicate the location of the fault. Refer to Intermittents and Poor Connections Diagnosis and Connector Repairs and Wiring Repairs in Wiring Systems.

### Test Description

Number(s) below refer to the step number(s) on the Diagnostic Table:

1. This vehicle is equipped with a PCM which utilizes an Electrically Erasable Programmable Read Only Memory (EEPROM). When the PCM is being replaced, the new PCM must be programmed.

2. For the PCM to check engine oil level, start-up engine coolant temperature must be at least 12°C (22°F) cooler than the engine coolant temperature was last time the ignition was turned OFF. Allowing the engine to warm and then cool ensures that the PCM checks the engine oil level switch and that the information displayed on the scan tool is current.

#### Engine Oil Level Switch Diagnosis

Step | Action | Value(s) | Yes | No
--- | --- | --- | --- | ---
1 | Important: : Ensure that engine oil level is not low (as indicated on dipstick) before continuing diagnosis. Was the ON Board Diagnostic (OBD) System Check performed? | -- | Go to Step 2 | Go to Powertrain On Board Diagnostic (OBD) System Check
2 | Observe Oil Level display on the scan tool. Does Oil Level display OK? | -- | Go to Powertrain Control Module Diagnosis | Go to Step 3
3 |

1. Turn the ignition OFF, disconnect the PCM connector.
2. With a J 35616-200 test lamp to battery positive voltage, probe the Oil Level Switch signal circuit at the PCM.

Is the testlight ON?

--

Go to Step 7

Go to Step 4

4 |

1. Turn the ignition OFF, reconnect the PCM.
2. Turn the ignition ON.
3. Raise the vehicle.
4. Disconnect the Oil Level Switch connector.
5. Connect J 39200 DMM to measure voltage between the Oil Level Switch terminals.

Does the DMM display voltage near the specified value?

B+

Go to Step 8

Go to Step 5

5 | Connect the DMM between the Oil Level Switch signal circuit and chassis ground. Does the DMM display a voltage near the specified value? | B+ | Go to Step 9 | Go to Step 6
6 |

1. Check the Oil Level Switch signal circuit for an open.
2. If a problem is found, repair as necessary. Refer to Wiring Repairs in Wiring Systems.

Was a problem found?

--

Go to Step 12

Go to Diagnostic Aids

7 |

1. Check for poor terminal connections at the PCM.
2. If a problem is found, repair as necessary. Refer to Wiring Repairs in Wiring Systems.

Was a problem found?

--

Go to Step 12

Go to Step 11

8 |

1. Check for poor terminal connections at the Oil Level Switch.
2. If a problem is found, repair as necessary. Refer to Wiring Repairs in Wiring Systems.

Was a problem found?

--

Go to Step 12

Go to Step 10

9 | Locate and repair open in the Oil Level Switch ground circuit. Refer to Wiring Repairs in Wiring Systems. Is the action complete? | -- | Go to Step 12 | --
10 | Replace the Oil Level Switch. Refer to Engine Oil Level Sensor and/or Switch Replacement . Is the action complete? | -- | Go to Step 12 | --
11 | Replace the PCM. Important: : Replacement PCM must be programmed. Refer to Powertrain Control Module Replacement/Programming . Is the action complete? | -- | Go to Step 12 | --
12 |

1. Start the engine and allow it to warm until engine coolant temperature is at least 70° C (158° F).
2. Turn OFF the ignition switch and allow the engine to cool for at least 15 minutes.
3. Turn ON the ignition switch.
4. Observe the Engine Oil Level display on the scan tool.

Does Oil Level display OK?

--

System OK

Go to Step 3