Aftermarket lights

[Noved1987]

I have a set of lights mounted to my rear bumper wired into the backup lights and on a switch. yesterday while checking all the lights on my truck i flipped the switch i mounted right under the reardefrost and rear wiper switches. lights came on.

Now the wierd part when i flipped the switch the fan for the heater also came on.

I should mention these lights have been installed for years and i havent noticed this. not saying it wasnt happening though.

also the lights are wired from the battery through the firewall to the switch then under the carpet to the lights. there is a ground on the switch for the on/off indicator light. it is grounded to the screw that holds the fuse box under the dash on the drivers side. you can see the screw next the the ebreak handle.

i checked all wires all good connections and not worn through or frayed.

i know the problem is after the switch because the fan is only on when the light switch is on

 

[Iceking007]

Have you checked the fan circuit? also does the fan come on and operate normally when you want? Ie lights off. Second of all I would note that it is good practice to always run a relay instead of the load through the switch. But that's not really a concern with your current settup as I understand two lights isn't much. What type of wirring did you install?

 

[Noved1987]

fan works as normal while driving. just when the trucks totally off and turn the back lights on the fan comes on. its been a long time since i installed them but i never use the wire that comes with them. i usually use a size or two larger (stranded). i know it is more than enought to carry the load.

Could it be the ground on the switch. thats the only thing i could think where the power connects to the vehicle except back by the bumper.

i will check tomorrow as long as it isnt pooring rain all day again. (probably taking the day off work)