Testing for Electrical Intermittents
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Testing for Electrical Intermittents
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Special Tools
J 39200 Digital Multimeter
Perform the following procedures while wiggling the harness from side to side. Continue this at convenient points (about 6 inches apart) while watching the test equipment.
If the fault is not identified, perform the procedure below using the MIN MAX feature on the J 39200 DMM. This feature allows you to manipulate the circuit without having to watch the J 39200 . The J 39200 will generate an audible tone when a change is detected.
Note
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J 39200 must be used in order to perform the following procedure since it can monitor current, resistance or voltage while recording the minimum (MIN) and maximum (MAX) values measured.
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1.
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Connect the J 39200 to both sides of a suspected connector (still connected), or from one end of a suspected circuit to the other. Refer to
Troubleshooting with a Digital Multimeter
for information on connecting the J 39200 to the circuit.
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2.
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Set the rotary dial of the J 39200 to the V (AC) or V (DC) position.
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3.
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Press the range button of the J 39200 in order to select the desired voltage range.
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4.
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Press the MIN MAX button of the J 39200. The J 39200 displays 100 ms RECORD and emits an audible tone (beep).
Note
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The 100 ms RECORD mode is the length of time an input must stay at a new value in order to record the full change.
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5.
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Simulate the condition that is potentially causing the intermittent connection, either by wiggling the connections or the wiring, test driving, or performing other operations. Refer to
Inducing Intermittent Fault Conditions
.
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6.
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Listen for the audible Min Max Alert which indicates that a new minimum or maximum value has been recorded.
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7.
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Press the MIN MAX button once in order to display the MAX value and note the value.
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8.
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Press the MIN MAX button again in order to display the MIN value and note the value.
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9.
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Determine the difference between the MIN and MAX values.
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If the variation between the recorded MIN and MAX voltage values is 1 V or greater an intermittent open or high resistance condition exists. Repair the condition as necessary.
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If the variation between the recorded MIN and MAX voltage values is less than 1 V, an intermittent open or high resistance condition does not exist.
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