Checking the wiring on a toad ...

brooksrimes · April 9, 2021

Last week I had a local collision shop (well recommended) install my baseplate and wiring. I used a plug and play wiring kit - no inserting of diodes and drilling extra lights into the taillights.

He did have to cut off the flat 4 plug and connect to a 7 pin adapter. We haven't taken delivery on the MH yet, so I couldn't test the turn signals last week.

Today I took the toad to the dealers to test the lights. Didn't go well, except the emergency flashers. Those worked in the toad. But a right turn signal in the MH caused no lights in the toad. A left turn in the MH caused both taillights to flash. Clearly something is wrong. I'm guessing Jayco knows how to wire the MH and the problem is in the toad wiring.

They make testers for the MH like this one: https://www.curtmfg.com/part/58650

But I'm not sure how to figure out what is wrong with the toad wiring and how to fix it.

Suggestions appreciated.

Kirk W · April 9, 2021

I am not sure what we can tell you without being there with a meter to troubleshoot but I will do my best. I would agree that it is probable that the RV is properly wired, but we can't know for sure. If you know someone who tows a trailer you might ask them to come by to connect to your new lights in order to troubleshoot. The device that you show only tests the connection from the motorhome and would not help to know what the problem is with the connections to the towed.

The fact that both brake lights flash when left turn is signaled tells me that there is a connection between them, which there should not be. Have you tested to see what happens if you use the left turn signal on your towed with no connection to the new plug? I am suspicious that you might just get the same reaction. Is there some reason not to take the towed back to the shop that did the wiring to get it done right? Your description of what you have makes me very concerned about what they may have done. If they connected a 4 wire system into a 7 pin plug it is quite possible that he didn't connect the right turn signals to the proper pin, but if the two tail lights flash with the left turn, I would not be surprised by the same happening with the right turn.

folivier · April 9, 2021

Wires for a trailer and for a toad are wired differently. Etrailer.com has wiring diagrams showing the differences.

brooksrimes · April 10, 2021

I have a multimeter.

This is the diagram I gave him to use for going from 4 to 6 poles. I mistyped in the first post. The connector is 6 poles not 7.

The lights on the toad function normally with no cable connected.

The shop that did the baseplate and wiring had not done those before. I asked them to test the wiring and they said they had no way to do that.

I had not heard that they wire trailers and MH differently.

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Kirk W · April 10, 2021

11 hours ago, brooksrimes said:

I had not heard that they wire trailers and MH differently.

Since either a trailer or a towed can be connected successfully to the same plug on the tow vehicle (I have done so many times), the connections at the connecting plug need to be exactly the same. The connections on the towed do have some differences from a trailer, unless you install different lights that are not used by the vehicle system because of the interconnecting of the lights with the normal wiring of the automobile. That is the reason that you must use blocking diodes with a vehicle lighting system when connecting it for towing.

The same connections apply to your towed vehicle but you need to deal with the connections from the vehicle harness. I suggest that you visit you-tube and watch one or two of the videos that they have about installing a kit to enable towing of a vehicle. That may help you to figure out what has been done and how to correct it. You have not said if you checked to see if all of the lights on the towed are working properly when not connected to the RV?

Zulu · April 10, 2021

If you can’t get the wiring working, try the Tekonsha module.

My RV-car tail light connection failed on the road and I didn’t have the time or money to troubleshoot it. The Tekonsha module works by induction, so you don’t have to cut into any wires.

brooksrimes · April 11, 2021

2 hours ago, Zulu said:

If you can’t get the wiring working, try the Tekonsha module.

My RV-car tail light connection failed on the road and I didn’t have the time or money to troubleshoot it. The Tekonsha module works by induction, so you don’t have to cut into any wires.

I used this kit from Hopkins which is basically the same as the Tekonsha: https://hopkinstowingsolutions.com/?t=products/dinghy-towing/plug-in-simple-diodes/56304 The Hopkins is "plug and play" and uses existing sockets which Honda left in the taillights. It doesn't require cutting into wires for diodes or drilling holes for extra lights. Unfortunately, it ends in a flat 4 plug as does the Tekonsha. Those type of plugs are popular with trailers. But all the motorhomes I've ever seen use round connectors, 6 or 7 pole. Therein lies the problem.

Edited April 11, 2021 by brooksrimes

brooksrimes · April 11, 2021

"You have not said if you checked to see if all of the lights on the towed are working properly when not connected to the RV?"

But I did: "The lights on the toad function normally with no cable connected."

I watched this video twice: https://www.etrailer.com/Tow-Bar-Wiring/Hopkins/HM56304.html

The problem is that it falls short of showing the connection between the motorhome and the toad.

The problem is the wiring kits end in a flat 4 connector and the MH uses a round connector. Things did not used to be this way.

Zulu · April 11, 2021

5 hours ago, brooksrimes said:

I used this kit from Hopkins which is basically the same as the Tekonsha: https://hopkinstowingsolutions.com/?t=products/dinghy-towing/plug-in-simple-diodes/56304 The Hopkins is "plug and play" and uses existing sockets which Honda left in the taillights. It doesn't require cutting into wires for diodes or drilling holes for extra lights. Unfortunately, it ends in a flat 4 plug as does the Tekonsha. Those type of plugs are popular with trailers. But all the motorhomes I've ever seen use round connectors, 6 or 7 pole. Therein lies the problem.

You missed this in my link above: FOURTH - 4-FLAT TO 7-WAY INTERFACE:

Kirk W · April 11, 2021

To me, your symptoms make me suspect that the installer connected something wrong.

brooksrimes · April 12, 2021

18 hours ago, Zulu said:

You missed this in my link above: FOURTH - 4-FLAT TO 7-WAY INTERFACE:

Thanks for the post. I didn't know all there were all those pictures going down the page. No offense, but I don't like the way that looks and its exactly what I was trying to avoid.

Ray,IN · April 14, 2021

On 4/11/2021 at 8:30 PM, brooksrimes said:

Thanks for the post. I didn't know all there were all those pictures going down the page. No offense, but I don't like the way that looks and its exactly what I was trying to avoid.

You sound like you desire a clean minimalist look on the rear cap right?

Your issue is simple enough to do IF you supply a drawing of what you have in mind and component locations you do desire. We will require a wire color schematic/chart for your towed vehicle.

Like the title of an old Hank Williams song; if you've got the money we've got the time.

Edited April 14, 2021 by Ray,IN