Electrical Circuit Inspection Procedure

• Continuity Check
• Voltage Check

If an open circuit occurs (as seen in FIG), it can be found by performing Step 2 (Continuity Check Method) or Step  3 (Voltage Check Method) as shown below.

Fig 1: Checking Open Circuit

Specification (Resistance)

1Ω or less → Normal Circuit

1MΩ or Higher → Open Circuit

1. Disconnect connectors (A), (C) and measure resistance between connector (A) and (C) as shown in [FIG. 2].

   In [FIG.2.] the measured resistance of line 1 and 2 is higher than 1MΩ and below 1 Ω 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.

   Fig 2: Continuity Check Method

   
2. Disconnect connector (B), and measure for resistance between connector (C) and (B1) and between (B2) and (A) as shown in [FIG. 3].

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 (B1).

Fig 3: Continuity Check Method

1. 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 [FIG. 4].

The measured voltage of each connector is 5V, 5V and 0V respectively. So the open circuit is between connector (C) and (B).

Fig 4: Voltage Check Method

• CHECK SHORT CIRCUIT 

• Continuity Check with Chassis Ground

If short to ground circuit occurs as shown in [FIG. 5], the broken point can be found by performing below Step  2 (Continuity Check Method with Chassis Ground) as shown below.

Fig 5: Checking Short Circuit

Specification (Resistance)

1Ω or less → Short to Ground Circuit

1MΩ or Higher → Normal Circuit

1. Disconnect connectors (A), (C) and measure for resistance between connector (A) and Chassis Ground as shown in [FIG. 6].

   The measured resistance of line 1 and 2 in this example is below 1 Ω 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.

   Fig 6: Continuity Check Method (With Chassis Ground)

   
2. Disconnect connector (B), and measure the resistance between connector (A) and chassis ground, and between (B1) and chassis ground as shown in [FIG. 7].

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).

Fig 7: Continuity Check Method (With Chassis Ground)