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.
