Circuit Description
There should always be a steady malfunction indicator lamp (MIL) when the ignition is ON and the engine is OFF. Battery ignition voltage is supplied to the lamp. The PCM will turn the lamp ON by grounding the ignition feed circuit.
Diagnostic Aids
If the engine cranks but will not run, check:
| • | Continuous battery-fuse or fusible link for open |
| • | PCM ignition fuse for open |
| • | Battery Feed circuit to PCM for open |
| • | Ignition Feed circuit to PCM for open |
| • | Poor connection to PCM |
An intermittent may be caused by any of the following conditions:
| • | A poor connection |
| • | Rubbed through wire insulation |
| • | A broken wire inside the insulation |
Thoroughly inspect any circuitry that is suspected of causing the intermittent complaint. Refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems.
If a repair is necessary, refer to Wiring Repairs or Connector Repairs in Wiring Systems.
Test Description
The numbers below refer to the step numbers on the diagnostic table.
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This step will isolate the problem in the MIL control circuit.
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If the Battery Feed, Ignition Feed and Diagnostic Test circuits have voltage, the PCM connections, grounds, or PCM are malfunctioning.
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If the fuse/fusible link is open, refer to PCM Wiring Diagram for complete circuit.
Step | Action | Values | Yes | No |
|---|---|---|---|---|
1 | Did you perform the Powertrain On-Board Diagnostic System check? | -- | ||
2 | Attempt to start the engine. Does the engine start? | -- | ||
3 | Check the fuse number 4. Is the fuse OK? | -- | ||
4 | Turn ON the ignition, probe the ignition feed circuit at the cluster connector with an unpowered test lamp connected to ground. Does the test lamp illuminate? | -- | ||
Is the MIL ON? | -- | |||
Check the PCM Ignition Feed and Battery Feed fuses. Are both of the fuses OK? | -- | |||
7 |
Is the test lamp ON both circuits? | -- | ||
8 |
Did you perform a repair? | -- | ||
9 |
Did you perform a repair? | -- | ||
10 |
Did you perform a repair? | -- | ||
11 | Repair the open in the ignition feed circuit to the cluster connector. Refer to Wiring Repairs in Wiring Systems. Is the action complete? | -- | -- | |
Locate and repair open in the PCM battery feed circuit or the PCM ignition feed circuit as necessary . Refer to Wiring Repairs in Wiring Systems. Is the action complete? | -- | -- | ||
13 | Locate and repair short to ground in the PCM ignition feed circuit or the PCM Battery Feed circuit as necessary. Refer to Wiring Repairs in Wiring Systems. Is the action complete? | -- | -- | |
14 | Locate and repair short to ground in the instrument cluster ignition feed circuit. Refer to Wiring Repairs in Wiring Systems. Is the action complete? | -- | -- | |
15 |
Important: The new PCM must be programmed. Replace the PCM. Refer to Powertrain Control Module Replacement/Programming . Is the action complete? | -- | -- | |
16 |
Did you perform a repair? | -- | ||
17 |
Is the bulb OK? | -- | ||
18 | Replace the MIL bulb. Is the action complete? | -- | -- | |
19 | Replace the instrument cluster. Refer to Instrument Cluster Replacement in Instrument Panel, Gauges and Console. Is the action complete? | -- | -- | |
20 |
Does the engine start and continue to run? | -- | ||
21 |
Are any DTCs displayed? | -- | Go to the applicable DTC | |
22 | Using the scan tool, select Capture Info, Review Info. Are any DTCs displayed that have not been diagnosed? | -- | Go to the applicable DTC. | System OK |
