Use a Headlamp as a Load in Place of the Fuse

Using a circuit breaker or short finder could potentially damage some circuits. A load which draws around 3 to 8 amps will work best.

Short-to-Ground Diagnostic Procedure

To determine the location of a short-to-ground:

1. Locate the blown fuse, and inspect its condition:

• If "blown cleanly" or is "charred"—you know that you have a direct short-to-ground condition.

• If it looks "melted"— a large amount of current flow went through it for a period of time; check for an overload condition. This could be caused by aftermarket accessory installations. This condition can also be caused by a source of heat adjacent to the fuse. A poor connection near or at the fuse, while causing less current flow in the circuit, can also generate a significant amount of heat which can damage the fuse.

• If fuse looks "fractured"—probably a defective fuse; replace the fuse and recheck the system.

2. Determine if the short-to-ground is intermittent or continuous.

• If it's not clear whether the fuse is blowing intermittently or on a continuous basis, (and if a supply of replacement fuses is available), replace the blown fuse with a new one, and retest the circuit.

Blown Fuses

The condition of a blown fuse can tell what cause the fuse to blow.

Fuse blown due to short-to-ground condition

Fuse has small fracture - defective fuse

Fuse melted by an overload condition or excessive heat adjacent to the fuse

• If the fuse is blowing intermittently, find out the exact conditions which cause the fuse to blow. This may point you directly to the problem circuit.

Do It Yourself Car Diagnosis

Do It Yourself Car Diagnosis

Don't pay hundreds of dollars to find out what is wrong with your car. This book is dedicated to helping the do it yourself home and independent technician understand and use OBD-II technology to diagnose and repair their own vehicles.

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