8 Volts on aux pin

[BriaBeck]

Hi guys,

My TV is only getting 8 volts on the aux power/charging pin at the connector on the truck.

Has anyone seen this before?

I'm going to dig into it next week when i have some days off, but any suggestions on the more obscure things that could be causing it are appreciated!

[pgandw]

Assuming you are measuring pin to pin, most likely cause is a bad wire connection at the back of the connector. Don't forget to check both ends of the ground wire.

Fred W

[pgandw]

Another possibility is that the aux pin has no power on it - blown or missing fuse, and you are getting feed through from a bad connection on another pin.


Fred W

[BriaBeck]

Measuring from the ground pin and also directly to chassis ground... gets the same reading. All the other pins are showing 13.8ish with the engine running.

[xd40c]

Sounds like there is a load between the source (13VDC) and your pin. Is there something running on this circuit that can be turned off or removed?

[clr]

Is the trailer plugged into the truck when you are making this measurement? If no there should be no load on this lead within the truck. If trailer is not connected and you still are reading 8 volts I would start by pulling the truck dedicated fuse for this circuit. If the fuse is OK the next item I would check is the relay in the truck that applies voltage to this pin. Infact I may change the relay just as a test. The relay is in the fuse box close to the fuse. I know that this is the way my Ford works but no expert on the other brands.

[BriaBeck]

Thanks guys.


This reading was directly in the 7 pin receptacle on the truck... with the engine running and the trailer NOT plugged in.


I don't have any idea what load would be in that circuit, and I don't think there should be, at least not on the truck.


I am thinking that it almost has to be inside the other side of the receptacle, where the truck's wiring harness plugs into the receptacle. I had to clean this out a few years ago, it probably just needs it again... at least I'm hoping so. It could possibly also be a relay, but with no load, I would think it would/should still show system voltage, unless the resistance across the relay is EXTREMELY high.

[clr]

I think that you are on the right track here. I assume you only have one 7 pin connector on your truck located on the bumper. If you have added another 7 pin connector within the bed for the 5th wheel I would compare the readings between the two and see what you get.

I know on my Ford you can unsnap the 7 pin from the bumper mount after you unplug the connector on the back. Makes it much easier to work on rather than laying down on the ground and looking up.

[BriaBeck]

Originally Posted by clr

I think that you are on the right track here. I assume you only have one 7 pin connector on your truck located on the bumper. If you have added another 7 pin connector within the bed for the 5th wheel I would compare the readings between the two and see what you get.

I know on my Ford you can unsnap the 7 pin from the bumper mount after you unplug the connector on the back. Makes it much easier to work on rather than laying down on the ground and looking up.

Good thought on the connector in the bed... which I DO have! I'll have to check that too. If it shows 12V, then I know the problem has to be in the lower receptacle. I forgot all about the receptacle in the bed!

[fonzie]

Is it pin #7 on this diagram that show low voltage? If it is, then I believe you need to put truck in reverse (make sure truck is not running and key is on accessory only for this) to get full voltage as it is the reversing circuit.

[clr]

Originally Posted by fonzie

Is it pin #7 on this diagram that show low voltage? If it is, then I believe you need to put truck in reverse (make sure truck is not running and key is on accessory only for this) to get full voltage as it is the reversing circuit.

I think that he is talking about the 7 pin connector and not pin 7 of the 7 pin connector. The aux pin is actual pin 4 within the 7 pin connector.

[BriaBeck]

Pin #4