Intermittent failures in electronic systems may be very difficult
to detect and accurately diagnose. For this reason, a good description of
the concern may be useful in locating an intermittent malfunction. Faulty
wires or connections cause most intermittent problems. When an intermittent
condition is suspected, inspect the suspected circuits for the following
conditions:
| • | Poor mating of connector halves of backed out terminals |
| • | Improperly formed or damaged terminals |
| • | Poor wire to terminal connections |
| • | Dirty or corroded terminals |
History DTCs are those indicating that the body control module (BCM)
has previously detected a malfunction. The reason could be either that the
malfunction is intermittent or that the system for which the DTC is set
for is not currently being operated. For this reason, if the BCM displays
history DTCs and the malfunction cannot be found easily, try clearing the
DTCs and manually operating the system that the DTC applies to using a
scan tool. Read the Diagnostic Aids and Conditions for Setting the DTC
in each DTC table for more specific information.
History DTCs help in diagnosing intermittent fault conditions but do
not necessarily indicate a faulty BCM. The BCM is a reliable component, and
is not the likely cause of the malfunction. Most system complaints are
linked to faulty wiring and connectors, and occasionally to a component.
Perform a thorough inspection of all related wiring and connectors pertaining
to the history DTC that is stored.
The following conditions may result in intermittent BCM operation with
no DTC stored:
| • | Any condition which results in the interruption of power to the
BCM |
| • | The battery or ignition voltage is out of range (below 9.0 volts
or above 16.0 volts). |
| • | A loose or damaged ground |
| • | An open or a short on the serial data line |
