LaCrosse FWD L4-2.4L (2011)
Seat Heater: Diagnostic Aids
Testing For Intermittent Conditions and Poor Connections
Testing for Intermittent Conditions and Poor Connections
Special Tools
EL-35616 - Terminal Test Probe Kit
For equivalent regional tools, refer to Special Tools (See: Power and Ground Distribution/Tools and Equipment).
When the condition is not currently present, but is indicated in DTC history, the cause may be intermittent. An intermittent may also be the cause when
there is a customer complaint, but the symptom cannot be duplicated. Refer to the Symptom Table of the system that is suspect of causing the condition
before trying to locate an intermittent condition.
Most intermittent conditions are caused by faulty electrical connections or wiring. Inspect for the following items:
*
Wiring broken inside the insulation
*
Poor connection between the male and female terminal at a connector
*
Poor terminal to wire connection - Some conditions which fall under this description are poor crimps, poor solder joints, crimping over the wire
insulation rather than the wire itself, and corrosion in the wire to terminal contact area, etc.
*
Pierced or damaged insulation can allow moisture to enter the wiring causing corrosion. The conductor can corrode inside the insulation, with little
visible evidence. Look for swollen and stiff sections of wire in the suspect circuits.
*
Wiring which has been pinched, cut, or its insulation rubbed through may cause an intermittent open or short as the bare area touches other wiring
or parts of the vehicle.
*
Wiring that comes in contact with hot or exhaust components
*
Refer to Inducing Intermittent Fault Conditions (See: Testing and Inspection/Component Tests and General Diagnostics/General Electrical
Diagnostic Procedures/Circuit Testing/Inducing Intermittent Fault Conditions) in order to duplicate the conditions required, in order to verify the
customer concern.
*
Refer to Testing for Electrical Intermittents (See: Testing and Inspection/Component Tests and General Diagnostics/General Electrical
Diagnostic Procedures/Circuit Testing/Testing for Electrical Intermittents) for test procedures to detect intermittent open, high resistance, short to
ground, and short to voltage conditions.
*
Refer to Scan Tool Snapshot Procedure (See: Testing and Inspection/Component Tests and General Diagnostics/General Electrical Diagnostic
Procedures/Circuit Testing/Scan Tool Snapshot Procedure) for advanced intermittent diagnosis and Vehicle Data Recorder operation.
Testing for Terminal Fretting
Some intermittent conditions can be caused by wire terminal fretting corrosion. Fretting corrosion is a build-up of insulating, oxidized wear debris that
can form when there is a small motion between electrical contacts. The oxidized wear debris can pile up enough at the electrical contact spots that the
electrical resistance across the connection increases. Movement between the contacting surfaces as small as 10 to 100 microns can cause fretting. To put
this in perspective, a sheet of paper is about 100 microns thick, so fretting motion is small and hard to see. Vibration and thermal expansion/contraction
are the main sources that create fretting motion. Since vehicles vibrate and can experience large temperature swings, they are a good source for fretting
motion. Tin, copper, nickel, and iron surfaces are all susceptible to fretting corrosion. Fretting corrosion can be difficult to see but it looks like small,
dark smudges on the terminals contact surface.
To correct a fretting condition disconnect the suspect connector and add Nyogel lubricant 760G (dielectric grease) to both sides of the connector
terminals. Then reconnect the connector and wipe away any excess lubricant. This will correct the additional terminal contact resistance due to the
terminal fretting corrosion.
Testing for Proper Terminal Contact
It is important to test terminal contact at the component and any inline connectors before replacing a suspect component. Mating terminals must be
inspected to ensure good terminal contact. A poor connection between the male and female terminal at a connector may be the result of contamination or
deformation.
Contamination may be caused by the connector halves being improperly connected. A missing or damaged connector seal, damage to the connector
itself, or exposing the terminals to moisture and dirt can also cause contamination. Contamination, usually in the underhood or underbody connectors,
leads to terminal corrosion, causing an open circuit or intermittently open circuit.
Deformation is caused by probing the mating side of a connector terminal without the proper adapter. Always use the EL-35616 when probing
connectors. Other causes of terminal deformation are improperly joining the connector halves, or repeatedly separating and joining the connector halves.
Deformation, usually to the female terminal contact tang, can result in poor terminal contact causing an open or intermittently open circuit.
Testing for Proper Terminal Contact in Bussed Electrical Centers
