An intermittent failure in an electrical system may be
very difficult to detect and to accurately diagnose. The ESC module tests
for different malfunctions under different vehicle conditions. For this
reason, a thorough test drive is often needed in order to repeat a malfunction
condition. If the system malfunction is not repeated during the test
drive, a good description of the complaint may be very useful in locating
an intermittent malfunction condition. Faulty wiring or electrical connectors
causes most intermittent problems. When an intermittent problem is suspected,
inspect the suspected circuits for the following:
| • | Poor mating of the connector halves or the terminals not fully
seated in the connector body (back out) |
| • | Deformed or damaged terminals |
| • | Poor wire to terminal connections |
| • | Dirty or corroded terminals |
| • | Damaged connector bodies |
History DTCs are those indicating that the ESC module has previously
detected a malfunction. The reason could be that either the malfunction is
intermittent, only happening occasionally, or that the criteria for
setting that particular DTC has not been met. History DTCs are used
in order to help diagnose any intermittent fault conditions and do not
necessarily indicate a faulty ESC module. The ESC module is a reliable
component and is not likely to be the cause of the malfunction. Most
system complaints are linked to faulty wiring or connectors, and occasionally
to a component. Perform a thorough inspection of all of the wiring and
connectors related to a particular DTC.
The following conditions may result in an intermittent operation of
the RTD system with no DTC stored:
| • | Any condition which results in the interruption of power to the
ESC module. |
| • | Battery or ignition voltage which is out of range (less than 10.3 volts
or above 16.0 volts). |
| • | Loose or damaged grounds. |
When diagnosing intermittent malfunctions with no DTC stored or no IPC
message, note that a fail-soft condition may have been taken in order to compensate
for the malfunction. For example, an intermittent loss of the position
sensor input would cause the RTD system to intermittently enter a fail-soft
action of speed-dependent shock absorber control to be taken. In this
fail-soft action, the RTD system does not use the position sensor data,
but instead uses the vehicle speed data. However, no DTC will be stored
and no IPC message will appear. If a vehicle is brought in with a ride
quality complaint, but no RTD DTCs are stored, refer to RTD Diagnostic
System Check before attempting any further diagnostic procedures.
