Towing Ranger behind RV

[oldwirelessranger]

When I tow my 2021 Ranger Lariat behind RV, lights work fine. When I mount my bike rack & carry bikes on short day trips, Ranger lights & external lights on bike rack work fine.
However, when I tow Ranger behind RV & plug in bike rack, the lights momentarily flash, then do not work on the Ranger nor on bike rack again.

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[airline tech]

So - (Flat Towing) - Ranger - In Neutral Tow
and
Bike Rack - Wired into - Trailer Tow Connector on the Ranger Bumper?

 

[oldwirelessranger]

Yes. Tow mode on Ranger menu, transmission in N, bike rack plugged into rear trailer connector. All connections made b4 power on RV. When lights are turned on in RV, the Ranger & bike rack lights will momentarily flash, then turn off. Power everything down, disconnect bike rack lights, power up RV, Ranger lights work properly. But they are difficult to see w/bikes on the rack.

 

[EricJo]

I tow a '23 4x4 behind my motorhome and installed the Roadmaster tail light kit. The kits power the tail lights on the Ranger using a diode to prevent power going the wrong direction. This does not power the 4/7 wire plugs on the back of the Ranger, so anything plugged into them won't work. I put my bike rack on the back of the motorhome using a 10,000 lb dual hitch adapter. My bikes don't cover the Ranger's tail lights. As backup, I do carry a magnetic light kit that has a long enough wire to reach the moterhome's 4 pin connector from the back of the ranger. https://www.etrailer.com/Hitch-Adapters/Roadmaster/RM-077-6.html
https://www.amazon.com/dp/B08SQLTQJ1?ref_=ppx_hzsearch_conn_dt_b_fed_asin_title_1&

 

[airline tech]

Since there is not a wiring diagram or detailed description on - How the (Neutral Tow) mode functions electrically, meaning what is actually taking place.

I know this much:

Neutral Tow Mode (Request) is completed via the HS1-Can bus
IPC - HS1-GWM
GWM - HS1 - PCM

So, the programming request comes from the HS1 Can Bus (data)

The Trailer wiring - (BCM) FET protection (4-Pin) Trailer Connector is on that HS1 Can Bus
Depending on if you are connected to the 7-Pin or 4-Pin Trailer Connector, varies on whether the TRM is included in the circuit.
But they share (1) circuit and that is the Park Lamps tie into Both the TRM (7-Pin) and the Direct to BJB (4-Pin) connectors.

The TRM - Data Bus - Uses the MS-CAN Bus, for Reference

So, one may try - if using the 7-Pin connector is to switch to the (4-Pin) connector to pinpoint down if this is a (FET) protected shutdown, due to (Truck is not powered) or the TRM (is tripping the power off)

I do not know what the results would be for trying the switch over to the 4-Pin but will say if it works - It is using the (Ranger) battery for power vs the RV's power source.

I actually think that -Neutral Tow Mode - is killing the circuit, the truck is not powered, so the Bat Save feature is triggered (On)
and the exterior lighting is (triggered) off as if you were to leave the headlights on (key-off) they will time out and turn off.

But without actually testing this out, 4-Pin vs 7-Pin is the only way to confirm, is the TRM the cause or is it the BCM and lighting control with a down powered truck.

 

[EricJo]

I don't think the 4 & 7 pin on the Ranger not working while towing behind the motorhome is specific to the Ranger, but more how the toad (vehicle towed behind a motorhome) light kits work. The 6-pin on the front of the toad has 3 wires that run to the tail lights; common running lights, bright left and bright right. The existing tail light running light and brake light wires are cut and diodes (one for running and one for brake/turn signal light on each side) with 2 inputs and 1 output are inserted between the existing wires and the tail light bulbs. The motorhome only powers the tail lights themselves and not the 4/7 pin on the back bumper of the Ranger. The Mazda MX-5 (Miata) I installed the kit on worked the same. Etrailer has a video of how the kits are installed.

 

[airline tech]

Yes, sometimes you overlook the oblivious and that the Trailer Lighting is powered from the Truck - Headlamp Switch position (Tail Lamps), so the only way to get power to the trailer lighting is to have the switch (in a powered) position, which with the truck off will be limited and also a battery drain - and this would only provide (Tail-Lamps) as there would be no inputs for Turn/Brake.

It is also easy to overlook (power wise) when looking at the wiring diagrams that the HS-1 Can bus is the main driver of the control of the trailer lighting circuit.
It sees that a trailer is connected, and based on inputs from the truck lighting circuit (main) lighting
It then (data transmits) what is happening (request) Park - Turn - Brake etc to a separate wiring circuit (Trailer Wiring) Relays & TRM

To be more specific - The Can Bus signal - via the BCM provides the Ground for the trailer circuit relays and without the BCM seeing a request on the Can Bus then the relay will never ground.

With Diode (installed) at the Trucks (Taillamps) the truck circuits never see anything (power wise) so it is unable to read and send that power over to the trailer lighting circuit.

So, an option would be - where you tap into the (Taillights) RV Powered, splice off of that and feed the Bike Rack -using the same Diode (inclusion) If the RV power source can handle the (Extra) lighting source.

 

[pete]

I don't have anything connected to the back of 2019 Ranger when towing it behind my motorhome. I decided to not trying pulling wires to the tail lights and adding diodes so I went with 22 Inch Towmate wireless light far. Magnetic attachment and simple. If I were adding something to the back of the Ranger I would mount the Towmate on the cab. The downside with the Towmate is more expensive than installing a light kit with wires and diodes.

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