Electrical intermittents can
be a source of frustration when repairing a vehicle. Some circuits in vehicles
are not only susceptible to an intermittent condition, but high resistance also
may cause erratic operation or set DTCs. An often overlooked possibility in the
diagnosis of electrical intermittent conditions is the quality of the terminal
crimps.
When diagnosing any type of
electrical condition, inspect the integrity of all related wiring harness
connectors and terminals. Poor connections may lead to numerous types of
intermittent conditions, such as miscellaneous DTCs, driveability conditions,
hard or no start conditions, incorrect gauge readings, illuminated MILs and
inoperative control module conditions.
Once the circuit that
connects the components in question has been isolated, perform a visual and
physical inspection of the wiring harness connectors for integrity. Many times,
repairs may be made by simply disconnecting and reconnecting the connectors.
A pull test of the terminals
should be performed after any wiring harness connector or terminal repairs.
Insert only the proper size terminal test tool into the terminal to determine
if the terminal is making good contact, or whether the terminal has been
damaged and needs to be replaced. It's critical to use the right tool when
testing. Most terminals in current module connectors (ECM, BCM, EBTCM) are
small 0.64 mm sq. terminals and can be damaged by probing with the wrong tool.
In many cases, once the
electrical integrity of the wiring harness is verified, the associated module
or component becomes suspect. However, it is possible for a harness that tests
as electrically conductive to be the source of an intermittent condition. The
electrical harness should have the terminal pins re-crimped before replacing a
module or component that tests OK.
The
correct crimping tool is required to consistently provide secure electrical
conditions.
For additional information on
the proper crimping procedure, an updated sealed splice installation sheet is
available on the TechConnect
Magazine website. Click the Troubleshooting PDF Job Aids link under Resources
on the right side of the page to print out the installation sheet PDF. (Fig. 7)
- Thanks to Tina Levi and
Mike DeSander
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