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Troubleshooting No Longer Getting Trailer Battery Charge From 1999 Ram 7-Way  


I have a 99 Dodge 3/4 ton pulling a 27 ft travel trailer and having trouble all of a sudden getting my battery charged on the trailer. My trailer dealer tells me that I have a bad fuse on the truck leading to my electrical hookup for the trailer. I have already checked the fuse on the trailer and that is ok. However, it was bad when this problem started. I have already checked the fuse under the hood and replaced it and that didnt do anything. I need help!


Expert Reply:

The first thing I recommend doing is testing the 7-Way at the rear of your Ram with a circuit tester like # PTW2979. Test the pin located at the 1 o'clock position and make sure you are getting appropriate power when the truck's running. This is the 12V charge circuit so if the tester isn't showing anything you know the issue is somewhere on the truck. If you do get power then the problem is somewhere on the trailer side.

If you did not get power with the tester then you will want to stay where you are and simply inspect the 7-Way itself for any debris or corrosion around the pins that needs to be cleaned out. Since you know the fuse is good the next step is to just try and trace the wire coming from the back of the 7-Way as far as you can, looking for any pinched or damaged areas that need to be replaced. This could be pretty difficult so if you know the problem is on the truck side then the best option may be to simply run a new power wire yourself.

You can do this by using a length of 10 gauge wiring # 10-1-1 (sold by the foot) from the 12V pin on the 7-Way up to the battery via a 40 amp breaker like # 9510.

If when testing the 7-Way you did get power then you can focus on the trailer. You will want to start at the trailer side 7-Way and again check for any debris or corrosion that needs cleaning. Then it will just be a matter of inspecting the 12V wire coming from the 7-Way and to the battery for any exposed areas that need to be replaced. Make sure the connections at the battery are secure as well.

expert reply by:
Chris R

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