How To Test A Wiring Harness And Find Bad Wires

Automotive


A short in the Mercedes wiring harness occurs when at least two of the harness wires makes contact. The electrical shortage typically results in some form of physical damage to the cables which can expose the bare conductors in the harness. Leaving the conductors exposed for an extended period of time can lead to more serious car trouble that can become life-threatening in a matter of seconds.

Faulty wiring and exposed Mercedes wiring harness should be detected right away to avoid any accidents. Although this is best done by professionals, you can follow these steps to do your own pre-diagnosis of a damaged wire harness:

Step 1: The Multimeter

First, the multimeter should be set on the continuity mode because in most multimeters the mode will give a clear and audible beeping sound as soon as two probe leads touch.

Step 2: Isolating Harness Wires Correctly

Try to isolate the end of the harness wires to prevent any bare conductors from getting too close to touch. In many instances, this will be difficult to do. If this applies to you, tape the wires on a non-conductive and flat surface such as a table top.

Step 3: Grouping The Wires

Take the two groups of wires from each end of the harness and group them together in two different bundles for easier handling.

Step 4: Connecting The Bare Conductors

Using the alligator clip, carefully, try to electrically connect the bare conductors in the two groups. This may seem hard and daunting at first, but as long as you are careful, this can be done with relative ease.

Step 5: Finding The First Short

Take the black probe end of the multimeter and clip it onto one of the wires in the bundle. Next, press the red probe into the other group of wires. The multimeter will beep if it detects a short in the wires.

Step 6: Rooting Out All Faulty Wires

Divide one bundle into two while keeping the connection to the multimeter intact. One of the small bundles will make a beep while the other will stay silent. Repeat this step over and over again until one wire is left. This is the damaged/faulty wire from the harness.

Step 7: Repeat Step Six

Repeat the same process with the other large bundle until all the faulty wires from that group are detected.

Step 8: Wire Replacement

The final step can be done at home if you have enough wire harness replacement skills. If not, removing and replacing exposed and faulty wires should be left at the hands of a professional. Remember that the wires carry an electric current and if they are mishandled, you can risk injuring yourself and also damaging your car in the process.

Sorting out the wires from the harness until the faulty ones are detected will take time, effort, and patience on your part. However, once all the broken wires have been weeded out from the bunch, you can easily replace them to ensure your Mercedes runs smoothly and safely once more.

If you need a Mercedes wiring harness, check out our online catalog at Adsit. We offer top quality car parts at affordable prices.