Electrical Intermittents and Terminal Crimping

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