Wayfarer 25RW turn signal error on Jeep JL Toad

[AnchorsAweigh]

We have a 2020 Mercedes/2021 Wayfarer 25RW pulling a 2019 Jeep JL Sport S. The tow package is Mopar dealer installed with a BlueOx tow bar and brake controller. Here's the odd situation I find myself dealing with... The turn-signal & brake lamps on the Jeep do not work when plugged into the 7-Way jack on the Wayfarer

* Prior to the 2019 Jeep JL I pulled a 2015 Jeep Wrangler JK without issue...
* I have connected other TOADS to the Tiffin (for test purposes) without problems
* I have successfully connected the Jeep to two other RV's without problems

When I connect the Jeep JL to our Tiffin, the brake lights and turn-sign indicators do not function.

I've tried load resistors across the left and right turn-signal wires to simulate standard bulbs. This, in one instance, has caused the blinkers to cycle twice as fast as they normally do, but did not help with the Jeep.

In order to successfully tow the vehicle I made a 7-way to 7-way straight-through connector with a spliced 4-way jack outlet for a standard trailer wiring hookup. I built a light bar from angle iron and mounted two brake/left/right-turn lamps on it and now run a 4-wire cable to the spliced 7-way jack on the Tiffin. This way the Jeep gets its 12 Volts to keep the battery charged while running the BlueOx, and the add-on turn signal/brake lights take care of tow navigation requirements.

Has anyone experienced anything similar to this with a Tiffin Wayfarer and Jeep JL with Mopar dealer wiring. I would really simplify hooking up the Jeep if the 7-Way --> Mopar cable worked as designed.

Note: Neither Mercedes, Tiffin, nor Jeep has any ideas about why I'm experiencing the problems I describe above.

Thanks, Bob

[MrMark52]

Time to get your voltmeter out and test the pin outs of both connectors.

Having a printout of the connector pinouts would probably be a good thing to have as well.

Have you confirmed the Mopar wiring harness (if was truly Mopar) had the diode pack to isolate the Lights from the Jeep and your coach?

I just installed the Curt “toad” harness on our new to us ‘18 JK. Just got the Blue Ox baseplate in today. Will probably be Thursday before I can test if all works OK - but I’m using the 4 pin flat connector, not the 7 pin round.

[luvlabs]

Your voltmeter will be useless on the Sprinter chassis since the 7 way plug is on the CanBus. Use a test light (not LED) to check.

The Sprinter uses a three light system so if the Jeep doesn't use a three light system, you will have to purchase a convertor box to go between the Sprinter to convert the output to 2 light.

[MrMark52]

Now that’s crazy!

Now I can’t just hook up our 1961 dinghy and head to the big pond!

Any idea for whatever reason they use CanBUS to feed trailer lights?

[AnchorsAweigh]

Thanks, Mark!

The harness is a Mopar item, installed by Jeep dealer. They also installed the BlueOx system.

I used the schematic & pin-out diagrams to build the adaptor for my external wiring/running-light solution. This is working fine.

Right now, we’re on the road, but I’ve exhausted all dealer help ( so far) and several other “wire experts” without results.

I’m told that there may be other 25RW-Jeep JL (Mopar harness) users with similar issues — hoping someone has solved the mystery. The problem may be rooted in the diode array you mention, or “load” configuration presented by the JL. As I mentioned in my post, the Jeep works with two other RV’s I’ve plugged into, and the Tiffin has successfully connected with another non-Jeep TOAD.

I have a background in electronics & electricity, although technology has advanced as much as my age��*♂️ and the two have diverged somewhat! Working on the RV & Jeep I find hidden parts and new-type connectors, among other things, that are baffling on discovery, only to find out later that I’m chasing the wrong “lead,” so to speak. I find little help from the dealerships involved.

Best wishes with your JK-BlueOx install.

Bob

[AnchorsAweigh]

Yes, I ended up using a test light to figure out the pin-out! The voltmeter does not load the canBUS enough to troubleshoot, although a 10k (I think that’s the value I used — brown, black, orange) resistor across the voltmeter leads can be useful to trick the canBUS for functional check, but I was shooting in the dark then.

Can you tell me more about this adaptor/converter box?

Thanks, Bob

[Lt Dan]

I'm not sure about the Mopar harness for JLs, but on both JKs where I installed a Mopar they require a 12v power connection to work. Check to see if you have a 12v charge or hot wire to the 7 pin connection and on some the ignition key has to be on to work. The first time I checked ours I couldn't figure out why it didn't work until I turned the ignition key on.

[TandW]

Why have you not had the dealer prove that his alterations are working?

[AnchorsAweigh]

Thanks, LT!

I'll look into this, but I was told the JL would not need to "on." There is 12V coming from the 7-Pin Tiffin jack and there is a connection to the MOPAR cable-adaptor plug.

Bob

[TandW]

Originally Posted by luvlabs

Your voltmeter will be useless on the Sprinter chassis since the 7 way plug is on the CanBus. Use a test light (not LED) to check.

The Sprinter uses a three light system so if the Jeep doesn't use a three light system, you will have to purchase a convertor box to go between the Sprinter to convert the output to 2 light.

My 08 Sprinter came with a six-way plug so I needed to add a combiner. If his newer Sprinter came with a seven-way the combiner may already be present.

[AnchorsAweigh]

Originally Posted by TandW

Why have you not had the dealer prove that his alterations are working?

Dealer says it's functioning. They plugged Jeep into another vehicle with 7-Pin jack and it worked. They said it is a Tiffin/Mercedes problem. Dealer says system performs according to specs.

[TandW]

Originally Posted by AnchorsAweigh

Dealer says it's functioning. They plugged Jeep into another vehicle with 7-Pin jack and it worked. They said it is a Tiffin/Mercedes problem. Dealer says system performs according to specs.

Do you have the parking lights working when 2 vehicles are hooked up?

[MrMark52]

What other make/model/year of toads have you connected to the Tiffin? And same for the Jeep to cars or coaches?

Was a 4 to 7 pin adapter used at any point?

Could it be a ground issue or some idiosyncrasy between the the two plugs that are preventing them from assembling together properly?

Will your Mercedes dealer let you come hook your Jeep up to a different coach?

[AnchorsAweigh]

Originally Posted by TandW

Do you have the parking lights working when 2 vehicles are hooked up?

No.