Refer to Engine Controls Schematics
I/P and Driver Information Display
for a wiring diagram.
Circuit Description
The powertrain control module (PCM) controlled lamps are powered through the IGN 1 fuse. The PCM energizes the bulb, the light-emitting diode (LED) , or the driver information center indicator by supplying a path to ground through the PCM.
The conditions which will illuminate each lamp are as follows:
| • | A low oil level lamp--When the ignition is first turned ON, the PCM briefly commands ON the Low Oil Level Lamp in order to test the bulb. The PCM also checks the engine oil level using the engine oil level switch input. The PCM determines whether or not to test for low oil level based on the difference between engine coolant temperature (ECT) at the last shutdown and the ECT at startup, in order to ensure that the oil has drained back into the sump before testing. To test for low oil level at startup, one of the following conditions must be present: |
| - | If the ECT was between 15°C (59°F) and 130°C (266°F) during the last key OFF, the ECT during key ON must be at least 12°C (22°F) cooler than the ECT at the last key OFF. |
| - | If the ECT was more than 82°C (180°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 in order 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 generator lamp--The PCM supplies battery voltage to the generator's internal regulator at generator terminal L. When a fault occurs in the charging system , the internal regulator grounds the L terminal voltage, and the PCM commands ON the generator. The PCM will command ON the generator lamp during the following conditions: |
| - | The engine speed is above 1200 RPM, and system voltage is less than 10 volts for at least 10 seconds. |
| - | The PCM detects a low voltage condition on the generator's L terminal for at least 10 seconds. |
| - | The engine speed is between 1000 RPM and 1300 RPM and the generator's F terminal duty cycle remains above 95 percent for 60 seconds. |
| - | OR |
| - | The engine speed is between 1000 RPM and 1300 RPM and the generator's F terminal duty cycle remains below 5 percent for 30 seconds. |
| • | The hot coolant lamp--The PCM will command ON the hot coolant lamp when engine coolant temperature is more than 124°C (255°F). The PCM will turn OFF the hot coolant lamp when the engine coolant temperature is less than 121°C (248°F). |
| • | The change oil lamp--The PCM commands ON the oil life monitor lamp when an oil change is required. The PCM calculates the remaining oil life based on the total engine revolutions and the calculated engine oil temperature for each startup since the oil life monitor reset. |
Diagnostic Aids
A PCM controlled lamp ON at all times can indicate that a condition requiring the attention of the vehicle operator is present.
Inspect for the following conditions:
| • | A poor connection at the PCM--Inspect the harness connectors for the following conditions: |
| - | Backed-out terminals |
| - | Improper mating |
| - | Broken locks |
| - | Improperly-formed terminals |
| - | Damaged terminals |
| - | Poor terminal-to-wire connections |
| • | A damaged harness--Inspect the wiring harness for damage. If the harness appears OK, disconnect the PCM and turn ON the ignition. Observe a Digital Multimeter (DMM) connected to the affected PCM output circuit while moving connectors and the wiring harnesses that are related to the PCM output circuit. A change in voltage will indicate the location of the fault. |
| • | The engine oil level switch circuit--Refer to Engine Oil Level Sensor and/or Switch Diagnosis . |
Test Description
The numbers below refer to the step numbers on the Diagnostic Table.
-
Normally, the ignition feed voltage should be present on the output control circuit with the PCM disconnected, the ignition ON, and the engine OFF.
-
This step tests for a shorted component or for a short to B+ on the output control circuit. Either condition will result in a measured current of more than 1.5 amps. This step also tests for a component that is opening during operation, resulting in a measured current of 0 amps.
-
This step tests for a malfunctioning instrument cluster.
-
This vehicle is equipped with a PCM which utilizes an electrically erasable programmable read-only memory (EEPROM). When you replace he PCM, you must program the new PCM.
Step | Action | Value(s) | Yes | No |
|---|---|---|---|---|
1 | Did you perform the Powertrain On-Board Diagnostic (OBD) System Check? | -- | ||
2 | Did you perform the Instrument Cluster System Check in Body and Accessories? | -- | Go to Instrument Cluster System Check in Instrument Panel, Gauges, and Console | |
Is the voltage near the specified value? | B+ | |||
Is the current reading between the specified values? | 0.05 Amp-1.5 Amps | |||
Is the voltage at the specified value? | 0V | |||
6 | Locate and repair the short to voltage in the affected PCM output circuit. Refer to Wiring Repairs in Wiring Systems. Did you complete the repair? | -- | -- | |
7 | Inspect the ignition feed fuse for the IPC and Driver Information Center indicator lamps. Is the fuse open? | -- | ||
8 |
Did you complete the repair? | -- | -- | |
9 |
Is the voltage near the specified value? | B+ | ||
10 |
Did you find and correct the condition? | -- | ||
11 |
Did you find and correct the condition? | -- | ||
12 |
Does the test lamp flash ON and OFF? | -- | Go to Diagnostic Aids | |
13 |
Did you find and correct the condition? | -- | ||
14 | Locate and repair the open in the ignition feed circuit to the indicator lamps. Refer to Wiring Repairs in Wiring Systems. Did you complete the repair? | -- | -- | |
15 | Replace the IPC. Refer to Instrument Cluster Replacement in Instrument Panel, Gauges and Console. Is the action complete? | -- | -- | |
|
Important: Replacement PCM must be programmed. Refer to Powertrain Control Module Replacement/Programming . Replace the PCM. Did you complete the replacement? | -- | -- | ||
17 | Use the scan tool output tests function in order to operate the affected lamp. Does the affected lamp operate properly? | -- | System OK |
