Important: The problem may or may not turn on the Service Vehicle Soon indicator
or store a DTC. DO NOT use the diagnostic trouble code (DTC) tables for intermittent
problems. The fault must be present in order to locate the problem.
Faulty electrical connections or wiring cause most intermittent problems.
Perform a careful visual/physical inspection. Inspect for the following conditions:
| • | The connector halves not fully seated in the connector (backed
out) |
| • | A terminal not fully seated in the connector (backed out) |
| • | Improperly formed terminal |
| | Carefully inspect all of the connector terminals in the problem circuit. |
| • | Poor terminal to wire connection |
| | Remove the terminal from the connector body in order to inspect the
connection. |
The vehicle may be driven with J 39200
Digital Multimeter connected to a suspended circuit. An abnormal
voltage when the malfunction occurs is a good indication that there is a fault
in the circuit being monitored.
Use a scan tool in order to help detect intermittent conditions. The
scan tool has several features that you may use in order to locate an intermittent
condition.
In order to verify the loss of DTC memory, complete the following steps:
- Disconnect the headlamps.
- Idle the engine until the Service Vehicle Soon indicator turns
on.
A number of DTCs should be stored and kept in memory when the ignition
switch is turned to the OFF position. If the DTCs are not stored and kept
in memory, the body control module (BCM) is faulty. When this test is completed,
ensure that you clear the DTCs from the memory.
The following problems may cause an intermittent Service Vehicle Soon
indicator with no stored DTC:
| • | The ignition coil may have shorted to ground, and be arcing at
the ignition wires. |
| • | Poor instrument cluster and BCM grounds. |
| | For information regarding these areas, refer to instrument cluster and
BCM wiring diagrams. |
Inspect for an electrical system interference. One of the following
conditions may be the cause of the interference:
| • | A defective PCM driven solenoid |
These electrical system interferences may cause a sharp electrical surge.
Normally, the problem will occur when the faulty component is located.
Inspect for proper installation of the following electrical options:
| • | Other electrical options |
All ignition control module (ICM) wiring should be kept away from the
generator.
Inspect for an open diode across the A/C compressor clutch. Inspect
for other open diodes.
