Checking Leads And Connectors

CHECKING WIRING AND CONNECTIONS

Many faults in the electrical system can be caused by wiring and terminals. These faults can be caused by interference from other electrical systems and mechanical or chemical damage.





Check Terminals Visually
^ Whenever the connector is disconnected for inspection or so that readings can be taken the terminals should be checked visually.

^ Checks:
- Look for oxidation, which may cause poor contact.
- Ensure that male pins are intact and that copper conductors are connected securely to pins.





Open-Circuit
^ An open-circuit in a lead can be indicated by the loss of a function (or functions).
^ Worn wiring and terminals which have come loose are common causes of faults.

^ Checks:
- Disconnect connector at each end of lead.
- Measure resistance by connecting ohmmeter to each end.

Instrument should read approx. 0 ohms if lead is intact.

^ Checking for Intermittent Open-Circuit:
- Inspect lead visually.
- Shake lead and pull connections gently during measurement to locate fault.





Short-Circuit to Ground
^ A short-circuit between a live lead and ground will usually result in failure of the circuit fuse or loss of a function (or functions).

^ Checks:
- Operate all switches and sensors in the circuit and check if fuse blows.
- Disconnect circuit component connectors to ensure that they do not affect measurements.
- Use ohmmeter to measure resistance between lead and ground.

Instrument should read infinity if no components are in circuit.

^ Checking for Intermittent Short-Circuit to Ground:
- Inspect lead visually.
- Shake lead and pull connections gently during measurement to locate fault.





Short-Circuit to Supply
^ A short-circuit between a lead and the supply will usually cause the circuit fuse to fail when the lead becomes live or may cause the loss of a function (or functions).

^ Checks:
- Use voltmeter to measure at various points of the circuit while operating switches and sensors.

Voltage indicated by instrument will depend on particular circuit and status of switches and sensors.

^ To locate short-circuits, use ohmmeter to measure resistance between suspect leads.

Instrument should read infinity when measuring resistance between leads not connected to each other in the circuit.

^ Checking for intermittent short-circuit to supply:
- Inspect lead visually.
- Shake lead and pull connections gently during measurement to locate fault.





Poor Contact (Terminals)
^ Poor contact in terminals may be caused by oxidation of the pins and sockets or by poor connection of the leads.
^ Poor contact causes the same faults as an intermittent open-circuit in a lead.

^ Checks:
- Inspect terminals visually.
- Shake lead and pull terminals gently during measurement to locate fault.

Contact Resistance and Oxidation
^ In theory, the resistance across contacts, leads and terminals should be 0 ohm. However, a certain resistance is always present due to oxidation of the terminals.
^ The function in question will be impaired if contact resistance becomes excessive. The value which is tolerable without impairment of the function is dependent on the circuit load. A typical value is a few ohms.

^ Checks:
- Inspect terminals visually.





Cleaning of Female Contacts and Male Pins

NOTE: Do not use rust removal spray or grease on either HO2S connector!

^ Disconnect battery minus cable.
^ Spray connector halves with rust remover, P/N 1161034-2.
^ Blow clean with compressed air.





Greasing of Female Contacts

NOTE: Do not put grease inside the casing.

^ Pack connector halves with grease, P/N 1161417-9, directly from tube.
^ Check that all terminal socket cavities are filled.





^ Use loose male pin to ensure that contact in sockets is good.
^ Pin should remain in posttion when pulled gently.