Electrical Circuit Inspection Procedure: Notes
- Open Circuit Test
- Procedures for Open Circuit
- Continuity Check
- Voltage Check
If an open circuit occurs (as seen in [FIG. 1]), it can be found by performing Step 2 (Continuity Check Method) or Step 3 (Voltage Check Method) as shown below.
- Continuity Check MethodNOTE:
- When measuring the resistance, lightly shake the wire harness vertically or horizontally.
Specification (Resistance)
1Ω or less → Normal Circuit
1MΩ or Higher → Open Circuit
- Disconnect connectors (A) and (C), and measure resistance between connectors (A) and (C) as shown in [FIG. 2].
In [FIG. 2], if the measured resistances in lines 1 and 2 are "over 1 MΩ" and "below 1Ω" respectively, line 1 has an open circuit.
(Line 2 is normal.) To find the exact broken point, check the sub line of line 1 as described in the next step.
- Disconnect connector (B), and measure the resistances between connectors (C) and (B1), and between (B2) and (A) as shown in [FIG. 3].
In this case, the measured resistance between connectors (C) and (B1) is higher than 1 MΩ and the open circuit is between terminal 1 of connector (C) and terminal 1 of connector (B1).
- Voltage Check Method
- With each connector still connected, measure the voltage between the chassis ground and terminal 1 of each of connectors (A), (B) and (C) as shown in [FIG. 4].
The measured voltages of connectors are 5V, 5V and 0V respectively. So the open circuit is between connectors (C) and (B).
- With each connector still connected, measure the voltage between the chassis ground and terminal 1 of each of connectors (A), (B) and (C) as shown in [FIG. 4].
- Procedures for Open Circuit