Contact resistance and oxidation

Fig 1: Identifying Terminal Inspection

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In theory, the resistance across contacts, leads and terminals should be 0 Ω. However, there is always some resistance due to terminal oxidation.

If resistance is too great there will be function problems. The magnitude of the resistance before it causes a malfunction depends on the circuit load. A guideline would be a few ohms.

Cleaning female socket terminals and male pin terminals 

Fig 2: Apply Rust Solvent Spray Or Grease To Connectors

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• Ignition off
• Disconnect the battery negative terminal
• Use compressed air to clean the disconnected connector
• Apply rust solvent spray 1161422 to the disconnected connectors
• Blow clean using compressed air.

Greasing female terminals 

Fig 3: Identifying Grease Pressed Into Terminals

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• Press grease, P/N 1161417-9, into the terminals directly from the tube
• Check that all the cavities in the connectors are filled
• Use a loose male pin to ensure that contact in sockets is good. The pin should remain in position when pulled gently.

Fig 4: Checking To Ensure Contact In Sockets Is Good

Courtesy of VOLVO CARS OF NORTH AMERICA.