Blowing fuse when turn on running lights

[akehurst89]

Hey guys I have a 1970 Dodge Dart swinger I did a full nut and bolt restoration on. I have a new engine and chassis harness but had to use old harness under the dash. So ever since I have reinstalled my dash I have had a issue where the second I turn my headlight switch to the running lights position it instantly blows the fuse. If I continue to switch to the head light position I still have headlights. Once it blows the fuse i still have headlights but no side Marker lights and no rear running lights. All the brake lights and turn signal work properly just my running lights. Could it be the switch itself causing a problem? Or a wiring issue? Any help would be appreciated on how to trouble shoot it.

 

[67Dart273]

It would be rare to be the switch.

WHAT YOU NEED to understand.......

There are TWO sources of power separately going INTO the light switch

One, unfused, comes from the ammeter "welded splice" is not fused and powers ONLY the headlights. The light switch has an internal circuit breaker for them

The second goes through the tail fuse and powers tail, park, and DASH lamps.

Very first thing I'd do is start to "simplify" the problem, and the very easiest way is to get into the left kick panel and separate the rear harness. In fact that is probably the most logical place for the short

If separating that connector does not eliminate the problem, go over the front lamps and harness, looking for damage. Examine the front marker lights, the park/ signal lamps, and follow the harness to the bulkhead connector. Look for melting, bare wires, evidence of physical damage