Wire Harness Inspection Procedure
- Before removing the wire harness, check the wire harness position and crimping in order to restore it correctly.
- Check whether the wire harness is twisted, pulled or loosened.
- Check whether the temperature of the wire harness is abnormally high.
- Check whether the wire harness is rotating, moving or vibrating against the sharp edge of a part.
- Check the connection between the wire harness and any installed part.
- If the covering of wire harness is damaged; secure, repair or replace the harness.
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.
- Continuity Check MethodNOTE: When measuring for resistance, lightly shake the wire harness above and below or from side to side.
Specification (Resistance)
1ohm or less --> Normal Circuit
1Mohm or Higher --> Open Circuit
- 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 1Mohm and 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.
- 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 1Mohm and the open circuit is between terminal 1 of connector (C) and terminal 1 of connector (B1).
- Disconnect connectors (A), (C) and measure resistance between connector (A) and (C) as shown in Fig 2
.
- 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 Fig 4
.
The measured voltage of each connector is 5V, 5V and 0V respectively. So the open circuit is between connector (C) and (B).
- 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
.
- 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 5 (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)
1ohm or less --> Short to Ground Circuit
1Mohm or Higher --> Normal Circuit
- 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 1Mohm 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 [Fig 7
].
The measured resistance between connector (B1) and chassis ground is 1ohm or less. The short to ground circuit is between terminal 1 of connector (C) and terminal 1 of connector (B1).
- Disconnect connectors (A), (C) and measure for resistance between connector (A) and Chassis Ground as shown in Fig 6
.
CHECK SHORT CIRCUIT