Intermittent failures in electronic systems may be very
difficult to detect and accurately diagnose. Faulty wires or connections cause
most intermitting problems. When an intermitting 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 |
The most likely causes of an intermittent no crank condition due to
the PASS-Key® system is either an incorrect resistance measurement or
an intermittent relay. If the no crank condition only happens with one key
only and not the others. Clean or replace the faulty key.
To check for an intermittent malfunction with ignition PASS-Key®
detection circuit or the ignition key itself, refer to the lock cylinder test.
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 UTD system. Always check for BCM PASS-Key®
DTCs first before diagnosing the UTD system.
The following conditions may result in intermittent UTD operation with
no associate UTD DTCs 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 grounds |
| • | Radio Frequency interference |
| • | An open or a short on the serial data line |
