I just replaced my tail light harnesses in my 1999 Pontiac grand am se and now when you turn on my headlights it blows out the 15 amp fuse. i know its a grounding prob but any ideas where?

Answer 1

Troubleshooting Circuits

You don't say what circuit the "15 Amp fuse" serves, but that is where the short circuit condition is located. If that is the circuit for the harness(s) you replaced, the that is where to look. IF the fuse serves another circuit not the one in which the harness was replaced, then you inadvertently caused the short in an adjacent circuit.

Depending on circumstances the short may have already been developing and your harness replacement aggravated the condition, or it could have been just a coincidence.

In any case, the "fix" is to carefully examine the conductors [wires/harnesses] of the circuit blowing the fuses.

I suggest that you start in the area where you were actually/physically working. Look for a conductor which is either "pinched" between two parts of the body sheet metal, OR makes a sharp turn [bend] around a sharp edge of the body sheet metal.

Either of these conditions can result in chaffing through, or cutting, of the insulation allowing the "hot" conductor to contact the grounded sheet metal.

Once the fault is identified, then it is a simple matter of moving the wire, re-insulating the damaged area properly, and securing the wire to prevent further pinching or chaffing.