Tow car behind motorhome how to get car's tail lights wired?

rjenkinsgb said:

In the car, both side brake lights will be wired together. You mean I should wire them together, or you're saying from factory they should already be wired together?
Likewise both tail lights, with the same feed for those operating the instrument lights, from the sound of it. Probably

Does the car have separate lamp filaments for tail & brake? I'm familiar with UK wiring but not that sure of the US wiring.. The car has two red bulbs on each side. The top red bulb is a small single filament bulb. The bottom red bulb is a larger bulb with two filaments. Top one is marker, bottom one is a "second" marker on one of its filaments, and the brake/stop light on the other filament.


Edit: Found an article that includes the relevant wiring diagrams for a 2006 CR-V:

Brake Lights Not Working?: 3 of the 5 Brake Lights Will Not Work ...

3 of the 5 brake lights will not work when I compress the brake. They do however light up when I turn the headlights on but when I hit the brake only...

www.2carpros.com

According to that, they have twin filament lamps for separate tail and brake wiring, in addition to the separate indicators. ok

Also, front and rear indicator and side (marker) lights will presumably be linked so the converter will be running two or more bulbs on each output. ok

From the description, you may have the converter "brake" output connected to the tail lights rather than brake lights?? I'll check and report back
If that diagram is correct and it uses separate lamp filaments, only the tail lights could backfeed to the cluster? I'll check and report back

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Diver300 said:

The converter ground, the RV ground and the car ground all have to be connected together. Yes, I wired it to the 7 pin connector on the RV hitch, it goes to the 6 pin connector on the car, and that goes straight to the car's negative battery post.

On the converter, the "left/brake" and the "right/brake" are inputs have to be connected to those lights on the back of the RV. The "left", "right" and "brake" are outputs that have to be connected to the indicators and the brake light on the car. I have the yellow left/brake, the green right/brake, and the brown taillight/marker wires from the 7 pin connector on the RV go to the 6 pin connector on the car, and it turn those yellow and green and brown wires go to the rear of the car by the tail light. The

"left", "right" and "brake" outputs are those I think I get stumped on.

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It is worth checking that there is no problem lighting the car indicators and brake light from a 12 V feed when the car is in the state it would normally be when being towed. Yes I have put power to each pin on the front of the 6 pin car connector and I can get all bulbs on the car to light up that way.

The tail lights, ignition feed and reversing light will correct directly from the RV to the car without any connection to the trailer. Yes, I have the brown 'tail/marker' wire from the 6 pin connector on the car going all the way through the car to the back and have "tee'd" it into the appropriate wire on the OEM/factory car wiring.

The hazards on the RV may not work with the 2 to 3 wire converter. Hmm

On a 2 to 3 wire converter, some behaviour depends on what was happening before. When both lights turn on at the same time that could either be the brakes coming on or the hazards starting a flash, and the converter may not know which is correct. Hmm

The inputs that the 2 to 3 wire converter sees are like this:-
Both off. No braking or indicating. Noted
Both on. Braking, or braking and indicating during the illuminated phase of the indicator flashing. Noted
One on. One side indicating, or the braking and the other side indicating during the off phase of the indicator flashing. Noted

The converter has to work out what to do depending on what happened before. Trying to include hazard light operation as well would be very difficult. Noted

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You mean I should wire them together, or you're saying from factory they should already be wired together?

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Diver300 said:

I'm not sure where the connectors are and it doesn't really matter. The connectors are there so that you can separate the car from the RV, but the connections will be the same wherever the connectors are positioned.

The 2 to 3 wire converter is expecting a ground that is connected to the RV ground and the car ground. Make sure that the grounds do connect together when the car is joined to the RV.

I suggest you get a bulb and connect one end to ground. Connect the other end to a connection on the RV and check that it causes the bulb to come on when the RV brakes are applied, and that causes the bulb to flash when indicating left and does nothing when indicating right. That connection needs to go to the "Left/brake" input on the 2 to 3 wire converter.

Similarly, find a connection on the RV that causes that bulb to come on when the RV brakes are applied, and that causes the bulb to flash when indicating right and does nothing when indicating left. That connection needs to go to the "Right/brake" input on the 2 to 3 wire converter.

On the car, find the wire that causes the left rear indicator to light when 12 V is applied to it. The left front and left side repeater indicators may light, they may not, it doesn't matter. That wire is connected to the "left" output of the 2 to 3 wire converter.

On the car, find the wire that causes the right rear indicator to light when 12 V is applied. The right front and right side repeater indicators may light, they may not, it doesn't matter. That wire is connected to the "right" output of the 2 to 3 wire converter.

On the car, find the wire that makes all three brake illuminate when 12 V is applied. If only one or two illuminate, find all the wires needed to illuminate the three brake lights, and put diodes on each one, with the cathodes connected to each wire, and join all the anodes together. If there was only one wire, don't bother with diodes and connect the wire that illuminates the brake lights to the "brake" output of the 2 - 3 wire converter. If there was more than one wire, connect all the anodes to the "brake" output of the 2 - 3 wire converter.

I hope this helps.

If you are still stuck, post some photos and diagrams.

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