Circuit Description
Ignition voltage is supplied directly to the Change Oil lamp. The PCM controls the lamp by grounding the control circuit via an internal switch called a driver. The primary function of the driver is to supply the ground for the component being controlled. Each driver has a fault line which is monitored by the PCM. When the PCM is commanding a component ON, the voltage of the control circuit should be low (near 0 volts). When the PCM is commanding the control circuit to a component OFF, the voltage potential of the circuit should be high (near battery voltage). If the fault detection circuit senses a voltage other than what is expected, the fault line status will change causing the DTC to set.
The PCM uses the distance the vehicle has traveled, Engine Coolant Temperature (ECT), engine oil temperature and engine revolutions to calculate oil life. Once a calibrated value is attained, the PCM will ground the lamp control circuit and the Change Oil lamp will illuminate.
The maximum mileage that can be accumulated before the PCM illuminates the Change Oil lamp is 7500 miles. However, the lamp may come ON sooner depending on engine load and temperature (trailer towing, high ambient temperatures, etc.).
Conditions for Setting the DTC
| • | Engine speed greater than 600 RPM. |
| • | The PCM detects that the commanded state of the driver and the actual state of the control circuit do not match. |
| • | Condition must be present for a minimum of 5 seconds. |
Action Taken When the DTC Sets
| • | DTC P1663 will be stored in the PCM memory when the diagnostic runs and fails. |
| • | The Malfunction Indicator Lamp (MIL) will not illuminate. |
| • | The PCM will record operating conditions at the time the diagnostic fails. This information will be stored in Failure Records. |
Conditions for Clearing the MIL/DTC
| • | If no failures are reported by this or any other non-emission related diagnostic. |
| • | A last test failed (Current DTC) will clear when the diagnostic runs and does not fail. |
| • | PCM battery voltage is interrupted. |
| • | Using a Scan tool. |
Diagnostic Aids
Using Freeze Frame and/or Failure Records data may aid in locating an intermittent condition. If the DTC cannot be duplicated, the information included in the Freeze Frame and/or Failure Records data can be useful in determining how many miles since the DTC set. The Fail Counter and Pass Counter can also be used to determine how many ignition cycles the diagnostic reported a pass and/or a fail. Operate vehicle within the same freeze frame conditions (RPM, load, vehicle speed, temperature etc.) that were noted. This will isolate when the DTC failed.
Test Description
Number(s) below refer to step numbers on the diagnostic table.
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Be sure that both the ON and the OFF states are commanded. Repeat the commands as necessary.
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If no trouble is found in the control circuit or the connection at the PCM, the PCM may be faulty, however, this is an extremely unlikely failure.
Step | Action | Value(s) | Yes | No | ||||||
|---|---|---|---|---|---|---|---|---|---|---|
1 | Was the Powertrain On-Board Diagnostic (OBD) System Check performed? | -- | ||||||||
2 |
Does the lamp turn ON and OFF with each command? | -- | Go to Diagnostic Aids | |||||||
3 |
Is the lamp OFF? | -- | ||||||||
4 | With a fused jumper wire connected to ground, probe the lamp control circuit in the PCM harness connector. Is the lamp ON? | -- | ||||||||
5 | Repair the lamp control circuit for a short to ground. Is the repair complete? | -- | -- | |||||||
6 | Check connections at the PCM. Was a problem found and corrected? | -- | ||||||||
7 | Check for the following conditions:
Is the repair complete? | -- | -- | |||||||
8 |
Important: Replacement PCM must be programmed. Refer to Powertrain Control Module Replacement/Programming . Replace the PCM. Is the action complete? | -- | -- | |||||||
9 |
Does the scan tool indicate that this test ran and passed? | -- | ||||||||
10 | Using the scan tool, select Capture Info, Review Info. Are any DTCs displayed that have not been diagnosed? | -- | Go to the applicable DTC table | System OK |
