[AT] Portable Trailer lights from Harbor Freight

[Alan Nadeau]

I pruned this quite a bit but the interesting part is copied below.

Somewhere in that whole mess of wiring there is a ground messed up.  The way 
the lights act sounds very similar to the system GM used for front side 
markers and turn signals combined into one, single filament lamp.  This was 
the case on the pickups I had and probably done anywhere they wanted the 
side marker to function as a side turn signal as well.

Daytime running, no lights on, the side marker would off and  blink on in 
time with the front turn signal.  Turn your vehicle lights on, the side 
marker would be on and blink off opposite of the front turn signal.  I hope 
that's clear as mud now.

They did it with different length ground paths that changed the potential in 
the wires feeding the turn & side markers and somehow (electric magic 
maybe?) end up trying to feed power both directions through the side marker 
or grounding back through the side marker, some such thing.  It has been 
years since I messed with that but I still have the GM wiring manuals which 
I could copy if anyone is all that interested.

Al Nadeau




>> Several months ago this was a topic on Atis when Harbor Freight had these 
>> light sets on sale for like $5 or $10 or so.  Well I bought two sets of 
>> them In case I needed then on my trailer and the second set to carry 
>> around in my truck for anyone else who might need them at an Antique 
>> Tractor show.  Well recently I decided maybe I ought to hooked one up to 
>> my truck and trailer to see how I liked them.  Didn't work so good.  The 
>> first indication was it appeared I had a crossed wire or poor ground 
>> since whenever I turned on a turn signal both turn signals blinked at a 
>> lower brightness.  Chased grounding, cleaned contacts, etc, etc.  No 
>> solution. Keep in mind my normal trailer lights are working fine. Then I 
>> found out that if the tail lights were on, night time, whenever I braked, 
>> both taillights would go out. Not dim, completely out.  That had me 
>> really going and then I found out that if the tail lights were not on, 
>> daytime, the brake lights worked just fine.   Now that had my h!
>> ead completely spinning.