NA. Checking the Wiring

NA. Checking the Wiring

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 the terminals visually. NA1
Break in the circuit. NA2
Grounding. NA3
Short circuits. NA4
Loose contact (intermittent break). NA5
Contact resistance in switches and connections. NA6
Cleaning. NA7

Intermittent Faults.
When intermittent faults occur the fault can often be found in wiring and terminals. Check as follows.

NA1




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

Check:
- Look for oxidation which could affect contact in the terminals.
- Check terminal pins and ensure that the copper conductor makes good contact with the pin.

NA2




Break in the circuit
A break in the circuit is indicated by the loss of a function. Worn wiring and terminals which have come loose are common causes of faults.

Check:
- Disconnect the connectors at both ends of the wiring.

Measure the resistance between the ends of the wiring using an ohmmeter.
The ohmmeter should read approx. 0 ohms on wiring without a break.

NA3




Grounding
Grounding is often indicated by the fuse blowing when a voltage is passed through the wiring.

Check:
- Activate all switches and sensors in the circuit and check to see if the fuse blows.
- Gently shake the wiring and pull the terminals while taking readings in order to detect intermittent faults.
- Disconnect circuit component connectors so that these do not affect readings.
Using an ohmmeter measure the resistance between the wiring and GND to detect any grounding.
The ohmmeter should read infinite resistance when no components are connected.

NA4




Short Circuits
Short circuits do not always blow the fuse. The fault is most often indicated by the loss of a function.

Check:
- Gently shake the wiring and pull the terminals while taking readings in order to detect intermittent faults.
1. Using a voltmeter take readings at various points in the circuit while activating switches and sensors.
The voltage indicated by the voltmeter depends on the circuit which is being measured and the position of switches and sensors. Use the circuit diagram to find the correct voltage in the circuit.
2. Using an ohmmeter take readings between suspected wires in order to locate short circuits.
The ohmmeter should read infinite resistance between wires which are not connected to each other in the circuit.

NA5




Loose Contact (intermittent Break)
Loose contact in connections is caused by the oxidation of pins and switches or poorly connected wiring.
Trace for faults in the same way as for breaks.

Check:
Disconnect the connectors at both ends of the wiring.
- Take readings using an ohmmeter or multimeter.
- Gently shake wiring and pull terminals while taking readings to find loose contacts.
The ohmmeter should read approx. 0 ohms.

NA6




Contact Resistance In Terminals
Resistance of connectors, leads and terminals should be 0 ohms, but there can always be some resistance because of wear and oxidation.
If resistance becomes too great, functions will be interrupted. The magnitude that this resistance must reach before there is interference varies with the load on the circuit. A guideline is a few ohms.

Check:
- Gently shake the wiring and pull the terminals while taking readings in order to detect intermittent faults.




- Using a loose male connector test to see if the female connector provides a good contact and if it and the pin stay together when the male connector is pulled lightly.
Using an ohmmeter take readings between the ends of wires.
Also take readings with switches and sensors connected in order to detect high contact resistance in these.
The ohmmeter should not read more than a few ohms in a circuit which has an acceptable resistance in contacts and terminals.

NA7

Cleaning Female Contacts And Male Pins

Note: Do not use rust removal spray or grease on any HO2S contacts.

- Disconnect battery minus cable.




- Apply rust removal spray 1161034-2 to exposed contacts.
- Blow clean with compressed air

^ Greasing Female Contacts

Note: Do not put grease inside the casing.




- Squeeze grease 1161417-9 into female contacts straight from the tube.
- Check that all contact sleeve holes are filled




- Using a spare male pin check that female contacts give a good contact and remain in place when the male pin is pulled lightly.