7 pin connector not powered

[charlie1047]

I'm having a tow bar / brake system put on my 2017 Jayco Melbourne 24K / Jeep Wrangled. The cab and chassis is a Mercedes Sprinter 3500. The installer called today and said there was no power to the 7 pin outlet on the chassis. Has anyone experienced this on a Jayco / Mercedes package?

[Dustdevil]

Don't know for sure about the Sprinter chassis wiring habits, but if you are referring to the constant 12v + that appears on one of the pins to charge the toad battery.... It's likely just a plug-in fuse or circuit breaker in one of the fuse blocks. Factories often leave them out. That's the way it is with both Chevy and Ford trucks, unless someone thought enough at the dealer to go in and add that.

[sailor]

Does the ignition switch need to on to get 12 volts at the connector?

[Jagiven]

Don't know about the sprinter. On my dodge, I had to change the fuse location. On the dodge, the fuse was in the fuse box under the hood.

I found the info in my owners manual.

[redsnapper]

Look for the fuse diagram on your vehicle and compare that with what you actually see inserted.

The fuse diagram will indicate what fuse is for what.....
As someone else has said, towing related fuses are often not there.

I found these fuses in a plastic baggie in the glove compartment......and once installed, had brakes and lights.

[Dustdevil]

Originally Posted by sailor

Does the ignition switch need to on to get 12 volts at the connector?

At least. In most pickup truck tow vehicles, not only does the ign key need to be "on", but the engine needs to actually be running for that pin to have power.

[bm9201]

I'm having trouble with my toad lights not working. They worked in the past on my Melbourne 25K. Do you know where the fuses for the 7 pin connector are located?
Also, do you know if Jayco installs any type of wire controller that is part of the trailer wiring?
We were suppose to leave yesterday but I have been troubleshooting the wires. I have narrowed it down to a problem in the Melbourne. May have to not tow this trip.

[Stavman]

Originally Posted by bm9201

I'm having trouble with my toad lights not working. They worked in the past on my Melbourne 25K. Do you know where the fuses for the 7 pin connector are located?
Also, do you know if Jayco installs any type of wire controller that is part of the trailer wiring?
We were suppose to leave yesterday but I have been troubleshooting the wires. I have narrowed it down to a problem in the Melbourne. May have to not tow this trip.

Did u actually test if there is juice in the connection at the RV plug vs the ambilical at the Toad?

I'd start there

Not sure any fuse exists

[Murff]

Is it just me or do others wish these questions were started in a new thread instead of resurrecting a 5 year old thread?

Just curious.

Murff

[bm9201]

Thanks for the quick response. I have voltage on the 7 pin socket when using a test light. None of the tail, brake or turn lights would work when I activacted each light.
I even tried an old 12 v light bulb on them but they did not work, but the test bulb worked on the hot wire.
I had the ignition turned to on (engine not started) when I tested them.

[craigav]

Originally Posted by bm9201

Thanks for the quick response. I have voltage on the 7 pin socket when using a test light. None of the tail, brake or turn lights would work when I activacted each light.
I even tried an old 12 v light bulb on them but they did not work, but the test bulb worked on the hot wire.
I had the ignition turned to on (engine not started) when I tested them.

Keep in mind that the connector plug at the rear of your Melbourne likely has a connector (wiring harness off of the trailer plug-in connector) specific for the tail, brake, and turn signals that is separate from the aux power connection. I would crawl underneath and try to follow the main cable going from the trailer connector to the vehicles harness (the larger and usually wrapped cable that actually has all of the tail lights wiring inside). Most all vehicles that I have seen (never checked a Melbourne) do not have a single separate fuse for "all" of the lights, therefore it would be unlikely that the issue is with a single fuse and also unlikely that multiple fuses blew all at once. I highly suspect that the connector is not fully plugged into the the Melbourne's tail light harness.

Also, some vehicles have an adapter between the towing vehicles lights and the towed vehicles lights, if you have one then it could be an issue. You would usually find this if it exists between the connectors wiring and the vehicles harness, so if you follow the connectors wiring to the RV's tail lights harness, you may find one and if so, it would need to be tested with your test light at that location (in front of and behind the adapter... again, if an adapter exists on yours). ~CA

[craigav]

Originally Posted by Murff

Is it just me or do others wish these questions were started in a new thread instead of resurrecting a 5 year old thread?

Just curious.

Murff

I have no concerns, especially when the new comment is closely related to the original posting. I agree that it may would be better to start a new posting and reference the old, however, I have no concerns either way, especially for our newer members and those who haven't made a lot of posts here. ~CA

[bucko]

Originally Posted by Murff

Is it just me or do others wish these questions were started in a new thread instead of resurrecting a 5 year old thread?

Just curious.

Murff

It is nice to see that folks are using the search function...and if the resurrect an old thread and question gets answered within old thread, it keeps the subject within one thread; easier for someone to search later and get an answer.

[bm9201]

Thanks for your help. I gently hammered the plug into the socket and the right toad turn signal came on so I then cleaned off the contacts with CRC electric cleaner and applied some electric grease and now all lights work.
We are now on our month long trip

[pconroy]

Originally Posted by Murff

Is it just me or do others wish these questions were started in a new thread instead of resurrecting a 5 year old thread?

Just curious.

Murff

Naaaaa.


All it did was remind me that the 7pin on my Greyhawk isn't powered either. It's on my "One of these days..." list.

[TOS]

Originally Posted by charlie1047

I'm having a tow bar / brake system put on my 2017 Jayco Melbourne 24K / Jeep Wrangled. The cab and chassis is a Mercedes Sprinter 3500. The installer called today and said there was no power to the 7 pin outlet on the chassis. Has anyone experienced this on a Jayco / Mercedes package?

Charlie, I had similar problem on my 2018/2019 Jayco 24L/ Mercedes. Toad a trailer to Utah and back with no issues. Then I got a Jeep and was rigging it up for toad, but couldn't get power to the 7pin or the 4 pin rear bumper sockets. Camping World nor MB dealer could find the fuse for the "pulse frequency modulator" (something I'd never heard of). I found the Modulator mounted near the chassis main frame on the drivers side about 3-4 feet from rear bumper. You can trace trailer plug wires from bumper to find it. Find the large red feed-in wire, it should have power to it (test with light or volt meter. MINE WAS DEAD, no power. I ran a 14 gauge wire from the modulator to the house battery (behind the entrance steps) with a 20 amp in-line fuse. It has worked with no problem since. The modulator is supposed to read erratic voltage and shut off instead of blowing a fuse.
Hope this will help you in some way. Good Luck and Safe Travels.

[Onyrlef]

Originally Posted by TOS

Charlie, I had similar problem on my 2018/2019 Jayco 24L/ Mercedes. Toad a trailer to Utah and back with no issues. Then I got a Jeep and was rigging it up for toad, but couldn't get power to the 7pin or the 4 pin rear bumper sockets. Camping World nor MB dealer could find the fuse for the "pulse frequency modulator" (something I'd never heard of). I found the Modulator mounted near the chassis main frame on the drivers side about 3-4 feet from rear bumper. You can trace trailer plug wires from bumper to find it. Find the large red feed-in wire, it should have power to it (test with light or volt meter. MINE WAS DEAD, no power. I ran a 14 gauge wire from the modulator to the house battery (behind the entrance steps) with a 20 amp in-line fuse. It has worked with no problem since. The modulator is supposed to read erratic voltage and shut off instead of blowing a fuse.
Hope this will help you in some way. Good Luck and Safe Travels.

I remove the heads and throttles on my trolling motors and rewire to pulse width modulators, you get more precise control ( infinite vs. step) in forward and reverse and significantly longer battery life.