For 1990-2009 cars
Engine Controls Components
Cell 20: Oil Life, Oil Level Switches
OBD II Symbol Description Notice

### Circuit Description

The PCM controlled lamps are powered through the instrument panel battery positive voltage or ignition positive voltage circuit. The PCM turns ON the bulb, LED, or driver info center indicator by supplying a path to ground through the PCM.

### Diagnostic Aids

A PCM controlled lamp ON at all times most likely indicates that a condition is present which requires the attention of the vehicle operator.

Low Oil Level Lamp - will be illuminated for about a minute after the ignition has been turned ON when the PCM tests for low oil level and the engine oil level switch indicates that a low oil level condition exists. The PCM determines whether or not to test for low oil level based on the difference between engine coolant temperature at the last shutdown and engine coolant temperature at startup. This is to ensure that the oil has drained back into the sump before testing. When the ignition is first turned ON, the PCM commands the Low Oil Level lamp ON for a brief period of time to test the bulb.

Check for the following conditions:

• | Poor connection at PCM. 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. Refer to Engine Oil Level Sensor and/or Switch Diagnosis .

### Test Description

Numbers below refer to the step numbers on the Diagnostic Chart.

1. Normally, ignition feed voltage should be present on the output control circuit with the PCM disconnected and the ignition turned ON.

2. Checks for a shorted component or a short to B+ on the output control circuit. Either condition would result in a measured current of over 500 milliamps. Also checks for a component that is going open while being operated, resulting in a measured current of 0 milliamps.

3. Checks for a short to voltage on the lamp control circuit.

4. 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.

#### PCM Controlled Lamps

Step | Action | Values | Yes | No
--- | --- | --- | --- | ---
1 | Was the Powertrain On-Board Diagnostic (OBD) System Check performed? | -- | Go to Step 2 | Go to Powertrain On Board Diagnostic (OBD) System Check
2 | Was the Instrument Cluster System Check performed? | -- | Go to Step 3 | Go to Diagnostic System Check - Instrument Cluster in Instrument Panel, Gauges and Console.
3 |

1. Turn OFF the ignition switch.
2. Disconnect the PCM.
3. Turn ON the ignition switch.
4. Using a J 39200 DMM, measure voltage between the affected lamp control circuit at the PCM harness connector and ground.

Is voltage near the specified value?

B+

Go to Step 4

Go to Step 7

4 |

1. Connect the DMM to measure current between the affected lamp control circuit and ground.
2. Monitor the current reading on the DMM for at least 2 minutes.

Does the current reading remain between the specified values?

0.05 -0.5 Amp

(50-500 mA)

Go to Step 12

Go to Step 5

5 |

1. Turn OFF the ignition switch.
2. Disconnect the instrument panel cluster (leave the PCM disconnected).
3. Turn ON the ignition switch.
4. Measure voltage between the affected lamp control circuit and ground.

Is voltage at the specified value?

0V

Go to Step 15

Go to Step 6

6 | Locate and repair the short to voltage in the affected PCM output circuit. Refer to Wiring Repairs . Is action complete? | -- | Go to Step 17 | --
7 | Check the ignition feed fuse for the instrument panel cluster indicator lamps. Is the fuse blown? | -- | Go to Step 8 | Go to Step 9
8 |

1. Locate and repair the short to ground in the ignition feed circuit for the instrument panel cluster indicator lamps. Refer to Wiring Repairs .
2. Replace the fuse.

Is action complete?

--

Go to Step 17

--

9 |

1. Disconnect the instrument panel cluster.
2. Turn ON the ignition switch.
3. Measure voltage between the ignition feed circuit for the instrument panel cluster indicator lamps and ground.

Is voltage near the specified value?

B+

Go to Step 10

Go to Step 14

10 |

1. Check the affected lamp control circuit for an open or a short to ground.
2. If a problem is found repair as necessary. Refer to Wiring Repairs .

Was a problem found?

--

Go to Step 17

Go to Step 11

11 |

1. Check the affected lamp control circuit and the ignition feed circuit for a poor connection at the instrument panel cluster or at the PCM.
2. If a problem is found, replace the loose terminals. Refer to Repairing Connector Terminals .

Was a problem found?

--

Go to Step 17

Go to Step 15

12 |

1. Turn OFF the ignition switch.
2. Reconnect the PCM and disconnect the instrument panel cluster.
3. Turn ON the ignition switch.
4. Connect a test lamp between the affected lamp control circuit and the ignition feed circuit at the instrument panel cluster harness connector.
5. Using the scan tool outputs test function, cycle the affected lamp ON and OFF.

Does the test lamp flash ON and OFF?

--

Go to Diagnostic Aids

Go to Step 13

13 |

1. Check the affected lamp control circuit for a poor connection at the PCM.
2. If a problem is found, replace the loose terminal. Refer to Repairing Connector Terminals .

Was a problem found?

--

Go to Step 17

Go to Step 16

14 | Locate and repair open in the ignition feed circuit to the instrument panel cluster indicator lamps. Refer to Wiring Repairs . Is action complete? | -- | Go to Step 17 | --
15 | Replace the instrument panel cluster. Refer to one of the following procedures in Instrument Panel, Gages and Console:

• | Instrument Cluster Replacement

• | Instrument Cluster Replacement

• | Instrument Cluster Replacement

Is action complete?

--

Go to Step 17

--

16 | Important: Replacement PCM must be programmed. Refer to Powertrain Control Module Replacement/Programming . Replace the PCM. Is action complete? | -- | Go to Step 17 | --
17 | Operate the affected lamp using the scan tool output tests function. Does the affected lamp operate properly? | -- | System OK | Go to Step 3