2004 Mercedes Benz E320 - Electrical Short

This 2004 Mercedes Benz E320 was towed into AAS directly from the Mercedes-Benz dealership because when the owner would drive the car more than 3 miles, a fuse would blow, and the car would turn off. The dealership was unable to locate the problem. The battery was dead when the sedan was brought to us, so we also replaced the battery with a brand new Bosch battery.

When we went to road test the car to diagnose the problem, the engine was skipping and running rough. We determined the number 6 ignition coil needed to be replaced (there are 6 ignition coils in this car). When we removed the worn out coil, we noticed it was melted on the underside . We found this very odd. After we replaced the number 6 ignition coil we road tested the car again. Within 5 minutes of driving the car, there was smoke coming from the engine compartment. A small electrical fire broke out over the number 6 ignition coil and melted the connector and coil. We knew we had a big problem on our hands. When we further inspected the coil on the left side of the engine (driver's side) we noticed the number 5 coil was melted too. We had to replace the electrical coil plug to replace the one that burned up. We could have kept putting more fuses in, but the problem was an electrical short. 

We found the problem with skill, but also a good amount of luck. The picture below shows the frayed and broken wires in the wiring harness. Check out video on Instagram (@almostautoservice). Once we repaired the wires in the wiring harness, the car drove normally and will continue to run normally for miles and miles and miles. All the fuses in the world wouldn't have fixed this car.