A 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 are the cause of most intermittent
problems. Perform a careful visual/physical inspection for the following conditions:
| • | Poor mating of the connector halves or a terminal not fully seated
in the connector (backed out) |
| • | An improperly formed terminal |
| • | Improper contact tension |
| | 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. |
You may drive the vehicle with a J 39200
connected to a suspected circuit. When a malfunction occurs,
an abnormal voltage 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. Use the scan tool
features in order to locate an intermittent condition.
In order to verify loss of the 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 store and remain in memory when the ignition
switch is turned to the OFF position. If this action does not occur, then
the body control module (BCM) is faulty. When you complete this test, clear
the DTCs from memory.
An intermittent SERVICE VEHICLE SOON indicator with no stored DTC may
result from the following conditions:
| • | The ignition coil shorted to ground |
| • | The ignition coil arcing at the ignition wires |
| • | Poor instrument cluster and BCM grounds |
Inspect for an electrical system interference caused by one of the following
components:
These conditions may cause a sharp electrical surge. Normally the problem
occurs when the faulty component is operated.
Inspect for improper installation of the following electrical options:
| • | Other electrical options |
Keep all ignition control module (ICM) wiring away from the generator.
Inspect for the following conditions. Refer to
Theft Deterrent System Schematics
.
- An open diode across the A/C compressor clutch
- Other open diodes
