How to Control the 12 Volt Power on the 7-Way for a 2009 Ford F-350

Question:

How, or can, I access the RV auxiliary circuit pin 7 - yellow so I can switch it on/off . I have a gravel/salt spreader installed on a 2009 F350 SD Ford. The truck has the factory trailer tow package installed. The spreader has mounted tail/turn/brake lights that connect thru a RV type 7 way plug to get their power. I have a vibrator draws 30 amps on the spreader that Id like to power thru that auxiliary. Currently I have a wire that I run under the truck dump bed to connect into the vibrator that gets its power from one of the up fitter switches. That works fine except having a separate wire to run back and connect up to the spreader. Id like to get the power thru the aux circuit and install a in cab switch on that. An alternative would be the 12 V power #4 black - again if I can switch it on-off in the cab.

asked by: David

Expert Reply:

In the passenger's footwell on your 2009 Ford F-350 there will be a fuse box. If you look in the #33 spot there should be a red 10 amp fuse. What you are going to want to do is start the vehicle and go test the 12 volt power pin (1 o'clock) on the vehicle's 7-way. If you remove this fuse does the 7-way lose power on the 12 volt power pin? If so then you are going to want to install a fuse bypass in this slot. The correct one will depend on what type of fuse it is. If you have a Mini fuse then use part # RM76511, or if you have a Maxi fuse use part # RM-76515. Use the fuse that you pulled and place that into this harness. If you don't know what type of fuse you pulled then google the above types and you can see which you have. This is going to act as a switch for the 12 volt power on your trailer connector. You can attach the vibrator to the trailer connector and then use this switch to power it off and on.

If the 12 volt power (1 o'clock) on the vehicle's 7-way does not lose power then you will want to try the #44 slot on the fuse box under the hood next to your engine. This should be a green 30 amp fuse. Use the above steps to check this to see if it cuts power to the 7-way. You can then use the fuse bypass on this locations if the above does not work but you may need to lengthen the wires to reach the cab.

expert reply by: Conner L