Electrical Circuit Inspection Procedure
- Check Open Circuit
- Procedures for Open Circuit
- Continuity Check
- Voltage Check
If an open circuit occurs (as seen in [Figure below]), 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 for resistance, lightly shake the wire harness above and below or from side to side.
Specification (Resistance)
1Ω or less → Normal Circuit 1MΩ or Higher → Open Circuit
- Disconnect connectors (A), (C) and measure resistance between connector (A) and (C) as shown in [Figure below].
In [Figure below] the measured resistance of line 1 and 2 is higher than 1MΩ and below 1Ω respectively. Specifically the open circuit is line 1 (Line 2 is normal). To find exact break point, check sub line of line 1 as described in next step.
- Disconnect connector (B), and measure for resistance between connector (C) and (B1) and between (B2) and (A) as shown in [Figure below].
In this case the measured resistance between connector (C) and (B1) is higher than 1MΩ and the open circuit is between terminal 1 of connector (C) and terminal 1 of connector (E
- Voltage Check Method
- With each connector still connected, measure the voltage between the chassis ground and terminal 1 of each connectors (A), (B) and (C) as shown in [Figure below].
The measured voltage of each connector is 5V, 5V and 0V respectively. So the open circuit is between connector (C) and (B).
- Check Short Circuit
- Test Method for Short to Ground Circuit
- Continuity Check with Chassis Ground
If short to ground circuit occurs as shown in [Figure below], the broken point can be found by performing Step 2 (Continuity Check Method with Chassis Ground) as shown below.
- Continuity Check Method (with Chassis Ground)NOTE:
- Lightly shake the wire harness above and below, or from side to side when measuring the resistance.
Specification (Resistance)
1Ω or less → Short to Ground Circuit
1MΩ or Higher → Normal Circuit
- Disconnect connectors (A), (C) and measure for resistance between connector (A) and Chassis Ground as shown in [Figure below].
The measured resistance of line 1 and 2 in this example is below 10 and higher than 1MΩ respectively. Specifically the short to ground circuit is line 1 (Line 2 is normal). To find exact broken point, check the sub line of line 1 as described in the following step.
- Disconnect connector (B), and measure the resistance between connector (A) and chassis ground, and between (B1) and chassis ground as shown in [Figure below].
The measured resistance between connector (B1) and chassis ground is 1Ω or less. The short to ground circuit is between terminal 1 of connector (C) and terminal 1 of connector (B1).