Parking/taillight fuse burns out

VMR

MEMBER
2003 PONTIAC VIBE
1.4L
4 CYL
2WD
AUTOMATIC
190,000 MILES

My son's car's parking/taillight/license plate lights are inoperable. The fuse on this circuit burns out as soon as the multi-function switch on the steering column is placed in park or headlight position. This problem seems identical to a December 2011 discussion on 2CARPROS where the technician recommended a signal tracer. I think this is the correct approach.
However, when piecing together the car's wiring diagrams there seems to be missing information. Between the "left of steering column behind storage compartment" connector and "right instrument panel junction block" connector it seems that there may be another connector and/or additional circuits not shown.
Can you please help with this?

Clarification on the car's wiring diagrams: I am referring to the three diagrams provided in the 2CARPROS response in December 2011. Sorry for not be clear about this.

2 Replies

CARADIODOC

MECHANIC
33,873 POSTS

Here is an easier approach. A simple trick to finding a short is to replace the blown fuse with a pair of spade terminals, then use small jumper wires to connect them to a twelve volt light bulb. A brake light bulb works well. When the circuit is live and the short is present, the bulb will be full brightness and hot so be sure it is not laying on the carpet or against a plastic door panel. Now you can unplug electrical connectors and move things around to see what makes the short go away. When it does, the bulb will get dim or go out.

You are not likely to find the cause of the problem under the dash where everything is protected. Better suspects are crushed wires in the trunk, chewed-up trailer wiring harnesses, and problems in bulb sockets. I have also found a few pinched wires behind tail lamp assemblies after someone spliced in trailer wiring to those wires. Those do not show up right away. It takes some time for screw's threads to work their way through the wire's insulation and cause a short.