Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
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 next step or step 3 .
- Continuity Check MethodNOTE: When measuring for resistance, lightly shake the wire harness above and below or from side to side.
Specification (Resistance)
1Ω or less --> Normal Circuit
1 MΩ 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 1Ω MΩ 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.
- 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).
- 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].
- CHECK SHORT CIRCUIT
- 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 next step .
- 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)
1Ω or less --> Short to Ground Circuit
1MΩ 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 Ω and higher than 1 MΩ 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 next 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 1Ω 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].
- Test Method for Short to Ground Circuit
NO RELATED
Use the Manual With the Right Hardware
Pair factory procedures with proven DIY tools so the instructions are easier to execute.
Affiliate disclosure: We may earn a commission at no extra cost to you.
When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.