12 Volt Circuit Does Not Work on a 2002 Mercury Mountaineer

Question:

ok in my 2002 mercury mountaineer i am trying to connect my boat trailer but i am not getting the 12 volt at the adopter that come attach to the suv is a 7 way plug the only 12 volts i am getting is went i put my head lights on... i am using a volt meter to check for my 12 voltage, main question is there is another fuse ,,, i did check the fuses inside under the hood and the ones under the steer wheel and also the one in the right panel in the back and all shows good. is there is another one i don t know where is can you help me please.... maybe i am missing a fuse but where is that fuse.

asked by: Angel

Expert Reply:

There are not a lot of boat trailers that require a 12 volt circuit but regardless it may not be a fuse you are looking for but a relay. Consult the vehicle owners manual for the locations of all fuses/relays associated with the factory tow package wiring. If there is a relay for the 12 volt circuit then the only way to really test it is to put a known good relay in its place. The manual will also cover any fuses you may have missed.

If your Mountaineer came with a 4-Way and you are using a 4- to 7-Way adapter like # 37185 that you have referenced then the 12 volt circuit will not be live unless you connect it to the vehicle battery via a 40 amp circuit breaker # PK54540 using wire # 12-1-1 sold in 1 foot increments. You also need to make sure the connector is grounded to the vehicle frame. The black wire on this adapter is for the 12 volt circuit. A regular 4-Way flat only has the basic lighting functions.

expert reply by: Michael H