Tail Lights Acting Up

[94StepSideSierra]

I am the proud owner of 1994 GMC Sierra Stepside. This trucks electrical system, however, I am not so proud of. My tail lights work just fine, until a hard rain comes, then the tailights blow the fuse, which also runs my dash lights! After a few days I can usually pop another fuse in and it won't blow it, but this is no exact science sometimes it takes one day, sometimes it might take a week. Also when my tail lights won't work, they will work when the truck is in reverse. Where is this problem? In the tail light housing? In the wiring system? In the switch? Where? Please help me out here guys, what should I do?

[GM-Tech]

Intermittent shorts can be difficult to track down. Does it have an added on trailer harness? This is the first thing I look for as the quality of the connections made are often questionable.

 

The tail lamp circuit board/socket assm has been somewhat problematic, but they usually open circuit, not short out. Is there water getting in there?

[94StepSideSierra]

Intermittent shorts can be difficult to track down.  Does it have an added on trailer harness?  This is the first thing I look for as the quality of the connections made are often questionable.

 

The tail lamp circuit board/socket assm has been somewhat problematic, but they usually open circuit, not short out.  Is there water getting in there?

 

<{POST_SNAPBACK}>

 

 

 

The trailer harness I am pretty sure is aftermarket, sense it is a Reece Hitch. I haven't checked for water, though I have thought about it, but if water is getting in, I have no idea how considering the housing is sealed.

[GM-Tech]

Can't tell you how many "sealed" taillight assemblies we've replaced when they come in with fish swimming around in them.