Truck came with a 7 way plug and the trailer I bought had a 6 way plug. So I bought a new 7 way plug for the trailer and installed it last night. Trailer lights work fine. Brake lights work fine. Hazard lights work fine. But if I just do one blinker (either direction) the dash indiccator blinks REALLY fast and there is no real change in the lights on the truck or trailer. they might just barely flicker. but thats it.

Any ideas?

Do I need to swap to a different flasher module?

BTW the trailer is a tandem axle car hauler. 4 corner marker lights and 4 tail lights.

 

I would try a heavy duty flasher, if you're sure your connections and grounds are good.

 

You need to replace the stock blinker module with an electronic type.

The regular kind uses a bi-metallic strip that when the standard load of bulbs is presented, it heats up and bends thus breaking the connection and turns off the bulb(s). When it cools, it bends back and re-establishes power to the bulbs to repeat the process.

The extra trailer bulbs are loading the blinker harder than designed.

The electronic type uses a regular timer to work a relay and therefore is immune to heavy loads influencing the blink speed.

Hope this makes sense.

 

My electronic ones worked great and never failed, even after 10 years.

 

The only "problem" with the electronic flashers is that they work even if you have a burnt out bulb.

Rick, putting relays on the trailer lights will allow you to keep the stock flasher.

 

Just went to Knecths and picked up a Heavy Duty Two Terminal Electronic Flasher, 'Cooper Bussmann' #BP/232 for about $6. Fixed it.

 

I have the EXACT same problem. Thanks for the two solutions recommended.