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Electrical Terminal Corrosion

Bulletin 5006

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All vehicle applications


Wire terminal corrosion has always been a problem in vehicle applications and not just the battery terminals. It’s estimated that the average motor vehicle today will have approximately 1 mile of wire with hundreds of terminal connections on board. Wire terminal connectors will always be susceptible to corrosion sometime during the lifecycle of the vehicle.


When you think of failure in an electrical circuit the most susceptible point of failure is the connector. Corrosion in an electrical connector can cause an intermittent or complete failure of the circuit and at times can be very hard to diagnose. Corrosion can be the result of either oxidation or galvanization with galvanic corrosion being the most common. Galvanic corrosion will occur when two dissimilar metals give up or collect electrons with the presence of an electrolyte like water.


When we think of corrosion, we think of the heavy green or white colored growth we may see on battery terminal connections, but corrosion isn’t always that heavy flowered growth. Corrosion can come in many different forms and may not always be easily seen or identified on a small electrical terminal connector. When in doubt always disassemble and refinish the contact surfaces and terminal tension to reestablish the connectors electrical contact.


To prevent corrosion on any surface, use a dielectric grease on the connector to prevent the one important element in the formation of corrosion, water. Water, or more effectively moisture on a connection, is the most important element which allows this corrosion to occur. Dielectric grease will prevent the galvanic corrosion from occurring in the first place. Applying a large application of the grease is not necessary or recommended, this is a case where to much is not a good thing. Apply just enough to cover the terminals but not enough that would impede the connector housing from latching together.


On spark plug secondary terminal connections always apply a small amount of grease to either the spark plug wire boot or the coil-on-plug to spark plug connection point. Don’t forget the terminals right at the ignition coil. The combination of high voltage and moisture is a recipe for quick terminal corrosion which will cause an intermittent or total misfire condition.


For further guidance on solving a corrosion problem contact a GoTech technical services team member.


This is an example of corroded ignition coil secondary terminals. Image 1 is the coil type. Image 2 is with the coil boots removed. Image 3 shows us the rusty corroded electrical terminals. Dielectric grease would prevent this.


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