Trailer Light Problem

[1956ford]

Just bought a 2001 F350 PSD. Hooked up my ATV trailer this AM and no lights.
Put a meter on the truck's connector and no voltage. Checked fuses under dash and hood - the ones I thought might be problems but all good.
Truck has 5th wheel setup with connector in bed in addition to the factory bumper trailer connectors. [I am using my '01 F150 plug in the truck connector since the 350's was missing.]
Any suggestions would be really appreciated.

 

[bushpilot]

i *THINK* the earlier, than my, truck had a relay under the hood
that needed to be installed...hopefully some one else will confirm or
this will give you enough to go on.

 

[stroked 350]

look in your owners manuel i'm pretty sure there fuse under the hood you need to put in

 

[Russ]

Is there power at the 5er plug? How is the 5er plug wired? did the installer cut the bumper plug wiring out to install the 5er plug?

 

[1956ford]

I downloaded an owner's manual and checked most of the fuses - all good including under hood. Did not check relays.
Put a VOM on the 5er plug in bed. With the truck flashers on, one of the contacts cycled from 0 to 5.2 to 10.7 volts. Other contacts read zero. Odd.
Crawled under the bed and wiring looks decent, as if they spliced into the factory harness to wire the 5er plug in bed.
Thanks for the suggestions. Guess I have to get more serious with the tracking. [I used to like this a lot more.]

 

[1956ford]

Thanks for all the help. Went back at it today and it was a bad ground and maybe some dirty terminals.
Hope I can give some sage advice sometime.