For 1990-2009 cars
Engine Controls Components
Cell 20: Generator, Oil Level Switch, EBTCM
OBD II Symbol Description 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 startup, one of the following conditions must be present:

• | If the engine coolant temperature was between 15°C (59°F) and 130°C (266°F) at the last key OFF. 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.

• | If the engine coolant temperature was higher than 82°C (150°F) at the last key OFF, the time between last key OFF and the present key ON must be sufficient to allow the oil to drain back to the sump. The PCM will remain powered up for 10 seconds to ensure that the oil has drained back to the sump. If the key is turned back ON while the PCM is still powered up, the oil level will not be tested.

The low oil level lamp will be illuminated for approximately 7 minutes 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 is not grounded). When the ignition is first turned ON, the PCM commands the low oil level lamp ON for a brief period of time in order to test the bulb.

### Diagnostic Aids

For diagnosis of the instrument panel, refer to Instrument Cluster System Check .

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.

• | 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.

• | Engine Oil Level Switch circuit.

| If the problem with the Low Oil Level lamp can not be isolated using the Engine Oil Level Switch Diagnostic table, refer to Powertrain Control Module Controlled Warning Lamps Diagnosis .

### 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, startup 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 engine oil level indicator) before continuing diagnosis. Was the Powertrain On-Board Diagnostic (OBD) System Check performed? | -- | Go to Step 2 | Go to Powertrain On Board Diagnostic (OBD) System Check
2 | Observe Engine Oil Level displayed on the scan tool. Does Engine Oil Level display OK? | -- | Go to Powertrain Control Module Controlled Warning Lamps Diagnosis | Go to Step 3
3 |

1. Turn OFF the ignition.
2. Disconnect the PCM connector.
3. Use a J 35616-200 or equivalent unpowered test lamp connected to B+ in order to probe the engine oil level switch signal circuit at the PCM.

Is the test lamp ON?

--

Go to Step 7

Go to Step 4

4 |

1. Turn OFF the ignition.
2. Reconnect the PCM.

Caution: To avoid any vehicle damage, serious personal injury or death when major components are removed from the vehicle and the vehicle is supported by a hoist, support the vehicle with jack stands at the opposite end from which the components are being removed and strap the vehicle to the hoist.

3. Turn ON the ignition.
4. Raise the vehicle.
5. Disconnect the engine oil level switch connector.
6. Connect a J 39200 DMM between the oil level indicator control and the engine oil level control in order to measure voltage between the engine 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 J 39200 DMM between the oil level indicator control and the engine oil level control in order to measure voltage between the engine 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 engine oil level switch signal circuit for an open.
2. If a problem is found, repair as necessary. Refer to Wiring Repairs .

Did you find a problem?

--

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 Intermittents and Poor Connections Diagnosis and Repairing Connector Terminals .

Did you find a problem?

--

Go to Step 12

Go to Step 11

8 |

1. Check for poor terminal connections at the engine oil level switch.
2. If a problem is found, repair as necessary. Refer to Intermittents and Poor Connections Diagnosis Repairing Connector Terminals in Wiring Systems.

Did you find a problem?

--

Go to Step 12

Go to Step 10

9 | Locate and repair open in the engine oil level switch ground circuit (CKT 451). Refer to Wiring Repairs . Is the action complete? | -- | Go to Step 12 | --
10 | Replace the engine oil level switch. Refer to Engine Oil Level Sensor and/or Switch Replacement . Is the action complete? | -- | Go to Step 12 | --
11 | Important:: The replacement PCM must be programmed. Refer to Powertrain Control Module Replacement/Programming . Replace the PCM. 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 and allow the engine to cool for at least 15 minutes.
3. Turn ON the ignition.
4. Observe Engine Oil Level display on the scan tool.

Does the Engine Oil Level display OK?

--

System OK

Go to Step 3