Brake light wiring help

[Woodwharf]

Hi I recently have had to install new brake lights on my 1983 fleetwood southwind Motorhome and I'm having trouble figuring out what the different colored wires are. I know the yellow wire on driver side and green wire on passenger side are for the turn signal and I'm assuming the black wire on each side is ground. But I also have 3 white wires. And that's where I'm getting confused. One of the white wires is thicker gauge then the other two. Could this thicker gauge white wire be for the brake light itself? Or is this the reverse light? When my friend is following me she says the light are dim and hard to see in the daylight. So if anyone has any input on this I would greatly appreciate. Thank you in advance.

[George3037]

Most all of the tailight wiring I have seen and done is:

As you determined,
Yellow and green wires for turn signals.
White for ground.
Black (or is it really Brown?) is for tail lights.

Very easy to check out with a voltmeter or a 12V test light and a helper.

[dougrainer]

Woodwharf wrote:
Thank you for the replies so far. The tail light assemblies on my motorhome were cracked and faded being its an 83. And the bulbs themselves were not grounding anymore so I had to replace the entire brake light/taillight assembly. And on my coach the brake and turn signal are red. But on my motorhome there are 5 wires for each side of the brake/ tail lights. 3 whites a black and yellow and green for each side.

1. 3 whites are all connected together for the ground
2. You have a universal taillight/brake assbly
3. IF you have the reverse light as part of the assbly, that usually is the YELLOW
4. The BLACK would be the Turn/Brake
5. The GREEN would be the running light.
6. With no pic but your description, you have a 3 light taillight assbly. The MIDDLE is usually the clear Reverse/Back up and the 2 outer are a dual bulb for Running and Brake/Turn. Doug

[D_E_Bishop]

It is kind of hard to explain in detail but if all your lights are working but as your friend said they are dim or if activating the right turn for example also activates another light, you have a missing ground some place.

If you are correct about the green and yellow, the black will be the tail light wire and as Doug said the three whites are going to be chassis grounds. The heavier white is most likely the ground from the chassis and the lighter gauge whites are most likely from other lights.

This is where a VOM or a DMM is invaluable. A VOM is an analog VOLT/OHM meter and a DMM is a digital multi meter. A test light can be used in lieu of a meter in many cases.

Using the OHM scale on the meter, touch one lead to a know chassis ground and the other to each of the white wires in turn, one will read zero and the other two should show a raised resistance to ground. The two with raised resistance feed lights somewhere else in the RV. The one without resistance is the chassis ground. Assuming you have standard dual filament light bulbs in the fixture, turn the tail lights on and touch the chassis ground to the common from the new fixture and the black from the RV to one of the colored wires from the fixture and then the other, The brightest light is the brake/turn light and the dimmest is the parking light.

Doug is usually right and so connect the three white wires on each side to the common from the fixture. Connect the black from the RV to the tail light wire and the yellow and green to their respective brake light wires.

Check what you have done and make sure all the brake/turn lamps, tail lights and DOT lights are operating. They should be. The license plate light should also be illuminated.

Then report back on your test so we know we helped.

[Woodwharf]

Thank you for the replies so far. The tail light assemblies on my motorhome were cracked and faded being its an 83. And the bulbs themselves were not grounding anymore so I had to replace the entire brake light/taillight assembly. And on my coach the brake and turn signal are red. But on my motorhome there are 5 wires for each side of the brake/ tail lights. 3 whites a black and yellow and green for each side.

[dougrainer]

White is ground. ALWAYS on Motorhomes and RV's. IF you do have reverse lights then black will be reverse. UNLESS The black is part of the New Light assbly. Then it will be ground and connected to those white wires. You have 3 whites because they daisy chain the ground to the upper clearance lights and probably to other rear 12 volt appliances. Doug

[midnightsadie]

I though white was all ways the ground?? I,m a old guy so maybe things have changed.

[FIRE_UP]

Woodwharf wrote:
Hi I recently have had to install new brake lights on my 1983 fleetwood southwind Motorhome and I'm having trouble figuring out what the different colored wires are. I know the yellow wire on driver side and green wire on passenger side are for the turn signal and I'm assuming the black wire on each side is ground. But I also have 3 white wires. And that's where I'm getting confused. One of the white wires is thicker gauge then the other two. Could this thicker gauge white wire be for the brake light itself? Or is this the reverse light? When my friend is following me she says the light are dim and hard to see in the daylight. So if anyone has any input on this I would greatly appreciate. Thank you in advance.

Woodwharf,
I'm a bit confused here. When you say you had to install new BRAKE LIGHTS, exactly WHAT did you need to install? I mean, did both brake lights go out on your coach, at the same time? Let me ask you, do you have AMBER turn signals or RED ones? If your brake lights were not functioning, it's highly possible your turn signals weren't either.
But, we need a bit more info on just what you mean by needing to replace the BRAKE LIGHTS.

If you talking about the tail lights on your coach, again, if you have Amber turn signals, then you'll have a totally separate set of lens's back there for brake lights and, that means more wires. But, if your turn signals are RED, then you'll have only three wires for each side. One wire for tail/marker lights, one wire for turn/brake, and one possibly for ground. Need more info.
Scott