Testing for Electrical Intermittents

Testing for Electrical Intermittents

Special Tools

EL-39200 Digital Multimeter

For equivalent regional tools, refer to Special Tools (Tools and Equipment).

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.

* Testing for Short to Ground (Testing for Short to Ground)
* Testing for Continuity (Testing for Continuity)
* Testing for a Short to Voltage (Testing for a Short to Voltage)

If the fault is not identified, perform the procedure below using the MIN MAX feature on the Digital Multimeter (DMM). This feature allows you to manipulate the circuit without having to watch the DMM. The DMM will generate an audible tone when a change is detected.

Note: The DMM must be used in order to perform the following procedure since the DMM can monitor current, resistance or voltage while recording the minimum (MIN), and maximum (MAX) values measured.

1. Connect the DMM 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 (Troubleshooting with a Digital Multimeter) for information on connecting the DMM to the circuit.
2. Set the DMM to the V (AC) or V (DC) position.
3. Select the voltage range feature of the DMM in order to select the desired voltage range.
4. Select the MIN MAX function of the DMM. The DMM displays 100 ms RECORD and emits an audible tone (beep).
Note: 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.

5. 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 (Inducing Intermittent Fault Conditions).
6. Listen for the audible Min Max Alert which indicates that a new minimum or maximum value has been recorded.
7. Press the MIN MAX button until the MAX value is displayed and note the value.
8. Press the MIN MAX button until the MIN value is displayed and note the value.
9. Determine the difference between the MIN and MAX values.

* 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.
* 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.