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Alan_Hepburn · 10-10-2019, 05:14 PM

I'm still working of getting our 2017 Jeep Wrangler ready to tow. The mechanical stuff is all ready, but I'm having issues with the electrical stuff.

The Jeep is wired with the Hopkins wiring harness, and it appears to work when I apply +12VDC to the individual pins.

The motorhome is a 5-wire setup, but has a factory-installed 5-to-4 converter at the back end. The wires coming out of that converter go to a standard 4-pin flat connector, and each pin has the correct voltage for its purpose. I have installed a brand new 7-pin round RV connector on the motorhome, wiring the 4 wires from the aforementioned connector to the proper pins on the 7-pin round connector, and I have the correct voltages at each pin.

I have an old Blue Ox 4-wire umbilical cable that I have installed a new 7-pin connector on one end and a 4-pin round connector on the other end, which connects to the 4-pin round connector on the Jeep.

Here's my problem: I get the correct voltages on each pin at the back of the motorhome, but when I plug the umbilical in I get running lights and brake lights on the Jeep, but no turn signals! Unplug the umbilical from the motorhome and the turn signal voltage is there. I'm at a loss to figure this out! Each wire in the umbilical has continuity from end to end, and there are no internal shorts; the connectors are secure, with no shorts - I'm wondering if it's some kind of issue with the 5-to-4 wire converter?

Jim_HiTek · 10-10-2019, 10:29 PM

Dunno about the 5to4 device, I would probably just remove it without much thought...I tend to go along with the majority of others that use a 7-blade to 6-pin system. Gives more wires to do stuff with and allows various setups for brakes and running and turn signals in the towed.

With that said, I wrote an article about my setup here: Towing Schematics...

Which covers many ways of doing it...and has some links to products (not sold by me) used here: History and setting up to tow...

And finally, here's a schematic on how I wired up my own towed. Note that the Winnie originally came with a 7-blade tow connector but the PO removed it and put in a 6-pin. Probably because he towed a trailer as I had a trailer connector under the dash when I bought it. I wanted the 7-blade back and installed it along with a couple more wires providing 12 volt and a beefy ground. Anyway, here's the schematic...

I sort of remember buying a 5to4 converter, but returned it as it wasn't needed. The diodes I show in the schematic are necessary to avoid interaction between the two systems. The 12 volt supply to the towed is to keep the battery in the towed charged over a long trip because you always have to leave the key on in the towed. Some manufacturers have you remove a fuse or two, but with the 12 volt supply that I added for mine, don't think that would be necessary typically.

Dark Sky · 10-11-2019, 09:21 AM

If you haven't done so you might try testing across the old Blue Ox cable, looking for continuity per pin and also check for any unwanted connection between or among pins. I had a two year old Blue Ox cable fail due to water ingress. It looked fine but prevented the bus brake lights from working while connected to it with no toad. And, it never blew a fuse.
Just something to try.

Mr_D · 10-11-2019, 09:45 AM

Jeep doesn't have a steering wheel lock so the ignition isn't left on. I used the Hopkins wiring kit on my '14 JKU Dragon model. Because the Jeeps brake lights work even with the ignition off and I use the Brakemaster aux braking unit I had to install the Roadmaster relay. That keeps the brake lights from getting voltage from both the MH and the Jeeps system.
I'd be checking the 5 to 4 way converter. You nay not need it. My MH doesn't but it's got a tow board with jumpers to set.

Alan_Hepburn · 10-11-2019, 04:47 PM

Thanks for the responses, guys - I've checked continuity on the umbilical: each wire has continuity from end-to-end with no shorts to other wires. I need a 5-to-4 converter SOMEWHERE in the system because the motorhome is a 5-wire system (brake lights and turn signals use separate lights) and the Jeep is a 4-wire system (brake lights and turn signals use the same lights). My next step is to replace the converter with a new one to see if that fixes things...

l1v3fr33ord1 · 10-11-2019, 05:37 PM

Alan-

Interesting... Both the brochure (link here) and owner's manual (link here) for your coach say Fleetwood shipped it with a 7-pin connector, with the standard signals in their expected places. No mention of a 4-pin or a converter.

What chassis is under your coach?

Alan_Hepburn · 10-11-2019, 06:53 PM

Quote:

Originally Posted by l1v3fr33ord1

Alan-

Interesting... Both the brochure (link here) and owner's manual (link here) for your coach say Fleetwood shipped it with a 7-pin connector, with the standard signals in their expected places. No mention of a 4-pin or a converter.

What chassis is under your coach?

We have the Workhorse chassis - it has a 7-pin connector, but it's wired with the converter in place. I guess they figured back in 2007 that there was more need to connect to the older system than the newer one! The connector does not even have the +12VDC or the backup light connections; just the GND, LT, RT, running lights, and trailer brake connections.

cwit · 10-14-2019, 06:45 AM

Back up lights are seldom if ever wired neither is 12 volt power.

Alan_Hepburn · 10-14-2019, 05:34 PM

Thanks everyone! I've decided on a simple, temporary soultion: I have an old set of magnetic lights that we used to use when we dolly towed our Ford Escape. I'm going to dig them out of their storage cabinet and give them a try!