I spliced a 4 pin(flat) trailer connector into the stock taillights. The lights flash very fast when hooked up to a trailer. I'm assuming this is due to the extra load of the trailer. Could I solve this by using a flasher with a higher load rating?

 

When does it flash fast? At all times? Only when the brakes are on? Only when both or only 1 side turns are on?

It sounds like something is not hooked up correct. The brake has to be off of the switch and not the tail lights.

 

Both sides do it. It doesnt matter if the brake is depressed or not.

 

It's a ground issue most likely, check that you have a dedicated ground wire to each light on the trailer from the trailer plug. and also that the ground on the truck side is clean and tight.

 

The answer is you need a heavy duty flasher!!!. Just stop at any auto parts store and get one. This is a normal thing to occur with a standard duty flasher.

 

I got the same problem, except only one of mine does that. every time i turn the blinker on it goes very fast and very dim... and if you keep doing it it will blow the fuse

 

Your problem is totally different than the OP. Your problem is that you have a short somewhere!!!

 

Thats exactly what I had assumed. I'll have to pick one up and see what happens.