Electrical Circuit Inspection Procedure

• Check Open Circuit

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.

Fig 1: Checking Open Circuit
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Continuity Check Method
NOTE: When measuring resistance, lightly shake the wire harness vertically or horizontally.

Specification (Resistance)

1Ω or less → Normal Circuit

1MΩ or Higher → Open Circuit
1. Disconnect connectors (A), (C) and measure resistance between connectors (A) and (C) as shown in Fig 2.
  In Fig 2, the measured resistances of line 1 and 2 are higher than 1 MΩ and below 1 Ω respectively. Specifically, an open circuit is in line 1. (Line 2 is normal.) To find the exact broken point, check the sub line of line 1 as described in the next step.
  
  Fig 2: Measuring Resistance Between Connectors (A) And (C)
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2. Disconnect connector (B), and measure the resistance between connectors (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 (C) And (B1)
  Courtesy of KIA MOTORS AMERICA, INC.
Voltage 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 voltages of each connector are 5V, 5V and 0V respectively. So, the open circuit is between connectors (C) and (B).

Fig 4: Measuring Voltage Between Chassis Ground And Terminal 1 Of Each Connectors

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• Check Short Circuit

How to Test Short to Ground 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 Step 2 (Continuity Check Method with Chassis Ground) as shown below.

Fig 5: Checking Short Circuit
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How to Check Continuity (with Chassis Ground)
NOTE: Lightly shake the wire harness up and down, or from side to side when measuring the resistance.

Specification (Resistance)

1Ω or less → Short to Ground Circuit

1MΩ or Higher → Normal Circuit
1. Disconnect connectors (A), (C) and measure the resistance between connector (A) and Chassis Ground as shown in Fig 6.
  The measured resistances of line 1 and 2 in this example are below 1 Ω and higher than 1 MΩ respectively. Specifically, the short to ground circuit is in line
2. (Line 2 is normal.) To find the exact broken point, check the sub line of line 1 as described in the following step.
  
  Fig 6: Measuring Resistance Between Connector (A) And Chassis Ground
  Courtesy of KIA MOTORS AMERICA, INC.
3. 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 Connector (B1) And Chassis Ground

Courtesy of KIA MOTORS AMERICA, INC.

• Voltage Drop Test

This test checks for voltage drop along a wire or through a connection of a switch.

Connect the positive lead of a voltmeter to the end of the wire (or to the side of the connector or switch) closest to the battery.
Connect the negative lead to the other end of the wire (or the other side of the connector or switch).
Operate the circuit.
The voltmeter will show the difference in voltage between the two points. A difference or drop of more than 0.1 volts (50 mV in 5 V circuits), may indicate a problem. Check the circuit for loose or dirty connections.

Fig 8: Testing Voltage Drop
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