Troubleshooting Trailer Battery Backfeed on 7-Way Auxiliary Circuit

Question

Question:

I just finished installing the 7pin cable with the leds. The led for the auxiliary circuit is on all the time even when not plugged into the tow vehicle. So obviously the circuit is energized by the house batteries. Any ideas?

asked by: Ron

0

Expert Reply:

Hi Ron; since the light remains on when you're not hooked up to the 7-way on your vehicle it indicates that a power backfeed from your house batteries like you said. This happens sometimes depending on how things are wired. The easiest solution is to add in a diode # RM-690 which will keep the power from running to the connector and powering the LED.

expert reply by: Robin H

0

Ron

9/26/2024

On what wire will I need to add the LED?

Robin H.

9/26/2024

@Ron black is the auxiliary power wire on the # HM20087 so you want to install the diode on the black wire.

Ron

9/26/2024

@RobinH I actually have 2 black wires. 1 coming from the tow vehicle via the 7 pin cable and a 14 gauge wire coming from the trailer that is connected to the blue wires from the rv and from the 7 pin cable. I suspect it needs to be installed on the 14 gauge wire before the blue wire connection. Your thoughts?

Robin H.

9/27/2024

@Ron it needs to be on the trailer side between the trailer connector and the battery on the auxiliary circuit since that is the one getting constant power.

See All (4) Replies to Ron ∨

Answer 1

Hi Randy, Are you just trying to charge the trailer batteries from the tow vehicle's 7-way? If so you're using the 12v aux pin on the 7-way and could place the diode on the trailer side just before the junction box to prevent any current from…

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Answer 2

Hi David; this is pretty common and all you really need is to throw in some simple diodes #RM-690. These will only allow power to flow in one direction so it will stop any backfeeding and power drain. It sounds like everything is in-line so you can…

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Answer 3

While unlikely, it is certainly possible that the trailer battery could backfeed to your vehicle's battery when hooked up under the scenario you described. To make sure this doesn't happen all you need to do is add a single diode like the…

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Answer 4

The Roadmaster Battery Charge Line Kit for Towed Vehicles #RM-156-25 has a circuit breaker to help isolate that circuit from issues, but it will not prevent back-feeding. If you want to prevent back-feeding which isn't typically an issue, you can…

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Answer 5

I spoke to my contact at Roadmaster who is considered by most to be the leader in flat-towing equipment and information. They informed me that you can prevent the battery drain issue you are having by installing a change line on your Nissan Frontier…

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Answer 6

Yes you need the diode arrow to point towards the brake controller. That will allow the voltage to travel into the controller but not backfeed back on to the Highlander in any way. If you need a diode we have the part #RM-690.

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Answer 7

It sounds like the tilt battery is backfeeding onto the breakaway battery charge line so as long as the ground is connecting it is taking a charge from the tilt battery and that is why your charge light is staying on. I have a solution for you, you…

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Answer 8

Wiring in the parking light diode #RM-690 is easy. All you have to do is locate the wire leading to the parking light bulb. Cut the wire and insert the diode in-line with the wiring. The IN side will be the part of the wire that leads to the front of…

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Answer 9

The breakers included with the #ETBC7 Brake Controller Installation Kit don't have diodes. If you're worried about unintentional power draw on that 12V trailer accessory feed discharging the vehicle battery, you can install an isolator…

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Answer 10

The difference between the Class II and Class III hitches has to do with their Gross Trailer Weight (GTW), their Tongue Weight (TW), and their Hitch Receiver Size. Class II trailer hitch receivers have a 1-1/4 inch receiver and can be rated up to…

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Answer 11

In order to determine the torque rating for the lug nuts on your trailer you will need to know check out the chart I attached that shows all of the torque specs for all the trailer lugs available based on stud size, wheel material and wheel size.

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Answer 12

A 4-Way trailer connector has the basic lighting functions only; running lights, left turn signal and brake lights, right turn signal and brake lights, and ground. A 7-Way has these functions and a 12 volt circuit, a circuit for electric trailer…

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Troubleshooting Trailer Battery Backfeed on 7-Way Auxiliary Circuit

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