Electrical Circuit Inspection Procedure

1. Continuity Check
2. Voltage Check

If an open circuit occurs (as shown in [Fig 1]), it can be found by performing Step 2 (Continuity Check Method) or Step  3 (Voltage Check Method).

Fig 1: Checking Open Circuit

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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: Measuring Resistance Between Connectors

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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: Measuring Resistance Between Connectors

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1. With each connector still connected, measure the voltage between the chassis ground and terminal 1 of each connector (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: Measuring Voltage Between Chassis Ground & Terminal 1 Of Each Connector

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1. Continuity Check with Chassis Ground

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

Fig 5: Identifying Short To Ground Circuit

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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: Measuring Resistance Between Connector & Chassis Ground

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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: Measuring Resistance Between Connectors & Chassis Ground

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