AMM A320F | CONTINUITY AND RESISTANCE TESTS

(1) This chapter has been prepared to include tests which should be performed after an engine harness has been repaired. When repairs are performed on an engine harness the new or repaired components should be checked to make sure that the parts have been replaced correctly.

(2) Tools and Equipment

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! REFERENCE ! DESIGNATION ! SUPPLIER !

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! Model 260 ! Ohmmeter or equivalent ! V16902 !

! Model 160B ! Digital Multimeter or equivalent ! V80164 !

! Model 1863 ! Megohmmeter or equivalent ! V24655 !

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(1) Do a wire continuity test when any of the following conditions apply:

(a) Test any wire which seems to be unsatisfactory.

(b) Test any wire which has been replaced.

(c) Test any wire which has had a new contact installed.

(2) Using the procedure which follows, test the wire from one end to the other using a Model 260 Ohmmeter, or equivalent.

(a) Disconnect the connectors at each end of the wire harness which contains the wire(s) to be tested.

(b) Prepare the ohmmeter for the test, as follows:

1 Set the function control of the Ohmmeter to OHMS.

2 Set the range control to the R X 1 ohms range.

3 Zero the ohmmeter.

CAUTION : DO NOT INSERT AN OVERSIZED TEST PROBE INTO A CONNECTOR SOCKET. THIS

COULD RESULT IN A DAMAGED CONTACT. DO NOT HANG A TEST LEAD FROM A CONTACT. THIS

COULD RESULT IN A BENT CONTACT.

(c) Connect the leads of the ohmmeter to each end of the wire and test the wire for continuity.

(d) The dial on the ohmmeter should stay on zero. If the dial moves to infinity it is possible the wire is broken.

(e) Move the wire to different positions. Make sure the dail on the ohmmeter stays on zero.

(f) Each circuit must have continuity from one end of the wire to the other end of the wire.

(g) If a circuit fails the continuity test, and a visual inspection of the harness shows no obvious damage, the cause could be a broken wire or a loose contact at the connector.

(h) Defective circuits must be repaired. Refer to the index at the beginning of Chapter 70 for the correct wire repair.

(1) Do a continuity test on an adapter or the backshell of a connector any time the following conditions apply.

(a) A connector has been replaced.

(b) An adapter or backshell has been replaced.

(c) An adapter or backshell has been removed and installed on the connector for any reason.

(2) Do the continuity test using a Model 160B Digital Multimeter or equivalent.

(a) The resistance must be no more than 0.01 ohm.

(b) Test the continuity from Termination A to Termination B.

(c) Each adapter/backshell must have continuity from Termination A to Termination B.

(1) Do a insulation resistance test on all repaired wires or on any unsatisfactory wires using a Model 1863 Megohmmeter, or equivalent.

CAUTION : YOU MUST DISCONNECT ALL THE CONNECTORS WHICH HAVE A RELATION TO THE

CIRCUITS IN THE CONNECTOR THAT IS TESTED. FAILURE TO DO THIS WILL

CAUSE UNSATISFACTORY RESISTANCE INDICATIONS AND POSSIBLE DAMAGE TO

THE CIRCUITS.

(a) Disconnect the connectors at each end of the wire harness which contains the repaired or unsatisfactory wire.

(b) Examine connector for contamination. Potting compound or oil should not be present:

1 On the face of the connector.

2 On the pins.

3 In the sockets.

(c) Set the megohmmeter to the 500 volt DC scale.

(d) Connect one test lead of the megohmmeter to the backshell body of the connector.

CAUTION : DO NOT INSERT AN OVERSIZED TEST PROBE INTO A CONNECTOR SOCKET.

THIS COULD RESULT IN A DAMAGED CONTACT. DO NOT HANG A TEST LEAD FROM

A CONTACT. THIS COULD RESULT IN A BENT CONTACT.

(e) Connect the other test lead to the contact (pin or socket) of the connector.

(f) Measure the resistance. The resistance must be a minimum of 20 megohms.

(1) Do a shorted wire test on unsatisfactory wires using a Model 1863 Megohmmeter, or equivalent.

CAUTION : YOU MUST DISCONNECT ALL OF THE CONNECTORS WHICH HAVE A RELATION TO

THE CIRCUITS THAT ARE BEING CHECKED. FAILURE TO DO THIS WILL CAUSE

UNSATISFACTORY RESISTANCE INDICATIONS AND POSSIBLE DAMAGE TO THE

CIRCUITS.

(a) Disconnect the connectors at each end of the wire harness which contains the unsatisfactory wire.

(b) Set the megohmmeter to the 100 volt DC scale.

CAUTION : DO NOT INSERT AN OVERSIZED TEST PROBE INTO A CONNECTOR SOCKET.

THIS COULD RESULT IN A DAMAGED CONTACT. DO NOT HANG A TEST LEAD FROM

A CONTACT. THIS COULD RESULT IN A BENT CONTACT.

(c) Connect the leads of the megohmmeter to each end of the wire and check the wires resistance.

(d) The resistance must be infinity.

(e) Defective circuits must be repaired. Refer to the index at the beginning of Chapter 70 for the correct wire repair.

CONTINUITY AND RESISTANCE TESTS - DESCRIPTION AND OPERATION