Tow vehicle fuse problem

[Lockman]

I was wondering if anyone had to increase the fuse rating that was part of a factory tow package when they went from the std. 4 pin connector to the 7 pin connector on their tow vehicle.



I had this problem when I started towing my new Scamp13 (with 2017 Patriot) and noticed I lost my exterior lights on the Scamp when I had the side markers and tail lights on, I believe it occurred when I stepped on the brakes. I really think that I had the flashers on as well when I stepped on the brakes causing the fuse to blow. I believe it would not blow as long as I did not have the flashers working.



After replacing the 20 amp fuse a number of times, I installed the next size up (30 amp fuse) to stop the problem.

Just wondering if this has happened to others with a factory tow package. Is it possible that the 4 pin tow wiring harness is rated for 20 amps??


I had the Tekonsha Prodigy 2 with the 7 pin brake mate professionally installed.

[gordon2]

No.. you dont replace fuses with higher rated ones! Thats a recipe for a serious problem.

In you situation it sounds like the factory tow package is not sufficient. You might well have to do like those without a tow package have to do.. install a converter so that the trailer lights are controlled by the tow veh lighting circuit, but draw their actual power from the battery. But first, lets look at the Jeep closer. Perhaps there is a simpler solution that is safe (unlike using 30 amp fuse where 20 is called for). 20 amps is a lot for just lights. Sounds like something else is going on that is not right.

[Lockman]

Gordon,


I know that upping the fuse capacity is not recommended, but considering the fact that I was 2,000 miles from home it was a judgement call as to which is the lesser of two evils. It may be that while driving from one place to another, with all the exterior lighting ,side markers, tail. flashers & brake lights and the fact that I put the refrig on 12volts, I may just be pushing the limits close to 20 amps, just enough over to blow the fuse.



Anyway, I will be taking the Jeep in for State inspection at the Jeep dealer this month and pose the question to them.

[steve dunham]

From my experiences as an electrician for over 40 years , I can guarantee you that the 20amp fuse is NOT the problem . Fuses are sized based on the size of the wire and usage .
There is another problem

[gordon2]

Originally Posted by Lockman

...with all the exterior lighting ,side markers, tail. flashers & brake lights and the fact that I put the refrig on 12volts, I may just be pushing the limits close to 20 amps, just enough over to blow the fuse.

Anyway, I will be taking the Jeep in for State inspection at the Jeep dealer this month and pose the question to them.

Your fridge should be on a totally different circuit from the trailer's running lights. Pull the fuse and kill the trailer lights.. with the trailer battery disconnected, if the fridge loses 12 volt power also but had it when the tow veh fuse was in, then thats what we call "a clue."

If your state inspection is anything like out state inspection, they will be of no help.

I bow to Steve's expert opinion.. and I happen to agree with it.

[John in Michigan]

Jack,

(1) Certainly don't put a 30 amp fuse where there was previously a 20 amp fuse in the tow vehicle UNLESS the owner's manual indicates that a 30 amp fuse is needed in that fuse slot.

(2) Since you are using a 7-pin towing harness and pressing the brakes causes the fuse to blow, next question is do you also have electric trailer brakes? If so, those electric trailer brakes draw 6 amps or more. Normally electric trailer brakes take power through a dedicated fuse directly from the towing vehicle battery. If instead your electric trailer brakes are wired to take power from the towing vehicle towing/trailer circuit, that could cause to fuse to blow when braking.

(3) Another way to reduce towing circuit power is to switch to LED bulbs on the camper running lights and tail lights.

The total power load through the 7-pin towing harness adds up:

- Two 1157 taillights draw 2.1 amps each when braking, .59 amps each when not braking
- Four #67 marker lights draw .59 amps each
- Refrigerator draws 10 amps
- Brakes draw at least 6 amps

If all of the above items are drawing power at the same time, total power draw is well over 20 amps.

[Eddie Longest]

See The E trailer video on the 2017 Patirot Trailer wiring harness adaptor. The adaptor increases amperage and isolates your trailer wiring. Did your installer install an adaptor when he installed a 7pin plug? Stock wiring in a lot of new vehicles is too light to handle the extra load of a trailer. I have seen these adaptors fail, if your installer installed one or if there was one there from the factory it could be bad.
Eddie

https://www.etrailer.com/t1-2017_Jeep_Patriot.htm

[Mike_L]

The fuse is never the problem, it warns you there is a problem somewhere else. A fuse limits the power going through the circuit to within the capacity of that circuit to protect it and other things from damage. The circuit is overloaded. That's the real problem. You should find out why and correct that.
Four pin and seven pin connectors are designed for different applications. Your seven pin connector is likely drawing too much power through the setup originally installed for a four pin application.

[ChuckLynn]

Had the same problem on a trip around Lake Superior a couple years ago. The fuse in the TV kept blowing. It took awhile to determine where the fuse was located in the TV, under the hood and buried under a mass of wires ( 2012 Pathfinder). We went to a Nissan dealer in Sault Ste. Marie, CA and talked to the service manager, who was very a knowledgeable person in TVs and RVs. As we walked to the Casita parked outside, he tapped the passenger side tail light and said "This is your problem." He hooked up a tester board he had between the TV and the Casita on the 7 pin connector. Did a couple tests and said, "Yes, that's your problem". He took the tail light/brake bulb out and checked the lead contact on the bottom. It was not making a good contact in the socket on the Casita. When the brake lights were turned on, the connection would cause an arc, which created a surge that blew the fuse in the TV. Changed the bulb. Time, 30 minutes, cost 5.00 with an extra bulb and fuses, and we were on our way with many thanks to dealership in Sault Ste Marie. We havbe not had the problem since.


ChuckLynn

[Lockman]

OK,

I called and talked to my Jeep Service Center to-day and my problem is that the Patriot cannot be wired the way it was, and a sensing module needs to be installed to correct the problem. It isolates the Tow Vehicle from the trailer and the module senses what is happening and applies the proper voltage to the corresponding item in the trailer, brake, turn signal etc.


I went to Etrailer.com and found the proper unit to interconnect with the rear light assemblies. Called etrailer and spoke to one of their people to confirm the solution and ordered the part.



Thanks to all who contributed info here, as always I am grateful for your input in solving problems.



Fellow Patriot owners, take notice and be aware of this problem!



Thanks guys,


Jack

[gordon2]

Originally Posted by Lockman

... a sensing module needs to be installed to correct the problem. ...
Fellow Patriot owners, take notice and be aware of this problem!

...

Good work. But its not just Patriots... many vehicles that are said to be tow ready are not tow ready. Or at least not ready for a RV (vs a small utility trailer for example). There are no standards for the use of the term "tow ready" and does not make things any easier when setting up a rig.