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Dave Gamble · 07-13-2019, 06:27 AM

Update: the pin chart provided by is identical to the one embossed on the plastic cap on the back of the F150. I tested the RH brake/stop light and it worked. I got nothing from pins 1 and 4, where I expected to see voltage. It didn't matter if the truck was running or not.

Next step was to test the related fuse. Ford does not make that easy at all. With the fuse out, I was able to see the diagram on the side - I'm not used to these big high power fuses. The diagram included what looks like a relay. I found continuity between the pins depicted as a fuse.

Figuring that there might be a need to actually have to the trailer attached (these Ford trucks think about things I would never have expected) I went ahead and did that. I had already found voltage provided by the converter, so I disconnected shore power and tested the terminals on the thick cables. It wasn't zero VDC - it showed .1

I plugged the trailer into the truck, started the truck, and tested again. I got 13+ VDC.

So, the battery seems to be getting everything it needs to not die.

Now I'm starting to question the battery again. It was a suspect early on, but it takes and holds a charge and has been deemed A-Okay by the smart charger I use, but perhaps I am putting to much faith in the charger and the fact that the battery is less than a year old. I'm also wondering how it could die in a less than 2 hour drive home with practically no draw on it. Perhaps it had been slowly dying during the five days we were out and just coincidentally died once we got back home. That would be quite a coincidence as this is the 2nd time it has happened. And with shore power and a working converter, what would deplete the battery during those five days?

It doesn't matter. I need to do a stress test on the battery - is that a thing, and how would I go about it, assuming this is the last possibility? Or, since it's an Interstate and they don't seem to have a lot of customer loyalty, should I just replace it with something better?

And before I forget, thanks to all of you for your advice.

07-13-2019, 06:27 AM	#7
Dave Gamble Member Join Date: Oct 2018 Location: Grove City Posts: 40	Update: the pin chart provided by is identical to the one embossed on the plastic cap on the back of the F150. I tested the RH brake/stop light and it worked. I got nothing from pins 1 and 4, where I expected to see voltage. It didn't matter if the truck was running or not. Next step was to test the related fuse. Ford does not make that easy at all. With the fuse out, I was able to see the diagram on the side - I'm not used to these big high power fuses. The diagram included what looks like a relay. I found continuity between the pins depicted as a fuse. Figuring that there might be a need to actually have to the trailer attached (these Ford trucks think about things I would never have expected) I went ahead and did that. I had already found voltage provided by the converter, so I disconnected shore power and tested the terminals on the thick cables. It wasn't zero VDC - it showed .1 I plugged the trailer into the truck, started the truck, and tested again. I got 13+ VDC. So, the battery seems to be getting everything it needs to not die. Now I'm starting to question the battery again. It was a suspect early on, but it takes and holds a charge and has been deemed A-Okay by the smart charger I use, but perhaps I am putting to much faith in the charger and the fact that the battery is less than a year old. I'm also wondering how it could die in a less than 2 hour drive home with practically no draw on it. Perhaps it had been slowly dying during the five days we were out and just coincidentally died once we got back home. That would be quite a coincidence as this is the 2nd time it has happened. And with shore power and a working converter, what would deplete the battery during those five days? It doesn't matter. I need to do a stress test on the battery - is that a thing, and how would I go about it, assuming this is the last possibility? Or, since it's an Interstate and they don't seem to have a lot of customer loyalty, should I just replace it with something better? And before I forget, thanks to all of you for your advice.