Electrical Circuit Inspection Procedure

ELECTRICAL CIRCUIT INSPECTION PROCEDURE

CHECK OPEN CIRCUIT

1. 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).

2. Continuity Check Method

NOTE: When measuring for resistance, lightly shake the wire harness above and below or from side to side.

Specification (Resistance)
1 Ohm less -> Normal Circuit
1 Mohm or Higher -> Open Circuit




a. 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 1 Mohm below 1 ohm 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.




b. 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 1 Mohm and the open circuit is between terminal 1 of connector (C) and terminal 1 of connector (B1).




3. Voltage Check Method
a. 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).

CHECK SHORT CIRCUIT




1. Test Method for 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 below Step 2 (Continuity Check Method with Chassis Ground).

2. 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)
1 ohm or less -> Short to Ground Circuit
1 Mohm or Higher -> Normal Circuit




a. 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 ohm and higher than 1 Mohm 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.




b. 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 1 ohm less. The short to ground circuit is between terminal 1 of connector (C) and terminal 1 of connector (B1).