Odd 7 to 4 wiring problem

[mcewena]

I've recently installed a brake controller on my RV as I'd planned to tow a trailer. I have confirmed it's working with a 7 pin LED tester.

Now I'm flat towing a car and I just want marker/brake lights, when I put in a 7 to 4 adapter and use a 4 pin LED tester I get left and right signals, tail lights but no brake lights even though the 7 pin tester showed the brake light working. I've tried 2 different 7 to 4 adapters.

Any ideas?

Thanks,

[RinconVTR]

gijoecam wrote:

RinconVTR wrote:

gijoecam wrote:
Maybe I'm mis-reading something... But the 7-pin connector is showing a left turn, a right turn, and BOTH when the brake is applied, right? There is (or should be) no separate BRAKE signal on a standard 7-pin adapter, and if there is, somebody has it wired wrong.

Did you word that wrong accidently? 4 pin brake lights are a combination of left/right at the same time. You said that, but its a little confusing. 7 pin to 4 pin have this wired within so the brake lights work, but the brake signal is not present.


http://www.etrailer.com/faq-wiring.aspx

I wouldn't say 'wrong' necessarily, but maybe 'poorly'...

I should have written, "There should be no separate BRAKE LIGHT signal in a standard 7-pin connector."

Yes, there is a BRAKE feed from the controller, but it does not power the brake lights on the trailer. What I wasn't understanding is the way the tester works. The BRAKE signal it indicates is for the feed to the trailer's brakes, not the brake lights on the trailer. Hitting the brakes on the tow vehicle should illuminate the left and right signal feeds at the 7-pin simultaneously.

Exactly!

[gijoecam]

RinconVTR wrote:

gijoecam wrote:
Maybe I'm mis-reading something... But the 7-pin connector is showing a left turn, a right turn, and BOTH when the brake is applied, right? There is (or should be) no separate BRAKE signal on a standard 7-pin adapter, and if there is, somebody has it wired wrong.

Did you word that wrong accidently? 4 pin brake lights are a combination of left/right at the same time. You said that, but its a little confusing. 7 pin to 4 pin have this wired within so the brake lights work, but the brake signal is not present.


http://www.etrailer.com/faq-wiring.aspx

I wouldn't say 'wrong' necessarily, but maybe 'poorly'...

I should have written, "There should be no separate BRAKE LIGHT signal in a standard 7-pin connector."

Yes, there is a BRAKE feed from the controller, but it does not power the brake lights on the trailer. What I wasn't understanding is the way the tester works. The BRAKE signal it indicates is for the feed to the trailer's brakes, not the brake lights on the trailer. Hitting the brakes on the tow vehicle should illuminate the left and right signal feeds at the 7-pin simultaneously.

[enblethen]

Thanks for the update!

[RinconVTR]

mcewena wrote:
I added a 3 to 2 converter up stream of the 7 pin connector and all is good.

That's great news, which also confirms Gijoe was right. The 7 pin on the TV was wired wrong.

[mcewena]

I added a 3 to 2 converter up stream of the 7 pin connector and all is good.

[RinconVTR]

gijoecam wrote:
Maybe I'm mis-reading something... But the 7-pin connector is showing a left turn, a right turn, and BOTH when the brake is applied, right? There is (or should be) no separate BRAKE signal on a standard 7-pin adapter, and if there is, somebody has it wired wrong.

Did you word that wrong accidently? 4 pin brake lights are a combination of left/right at the same time. You said that, but its a little confusing. 7 pin to 4 pin have this wired within so the brake lights work, but the brake signal is not present.


http://www.etrailer.com/faq-wiring.aspx

[RinconVTR]

mcewena wrote:

TubaPete wrote:
Sounds like your tow vehicle has seperate lights for turn and brake (amber and red, maybe). A 4 pin combines turn and brake into one light on each side. You need to install a wiring adapterin your vehicle to combine the two lights on eahc side into one. You can get it at almost any big box store, e.g. Walmart, that carries automotive supplies.

You mean the 7 to 4 doesn't include that function?

Thanks.

It absolutely does.

You don't need a converter (or anything else!) when you already have a working 7 pin wired on the TV.

[mcewena]

gijoecam wrote:
Maybe I'm mis-reading something... But the 7-pin connector is showing a left turn, a right turn, and BOTH when the brake is applied, right? There is (or should be) no separate BRAKE signal on a standard 7-pin adapter, and if there is, somebody has it wired wrong.

My 7 pin tester looks similar to the link in post 5 above, it has a separate brake signal (middle bottom row) however that's the trailer brake power signal (blue). I was assuming the blue trailer brake wire would also be used for any 7 pin trailers brake lights as well as the brakes themselves. So when the turn signal lights on the tester didn't come on but the brake signal did I didn't see that as a problem.

I see now from tailer wiring diagrams that that wouldn't be the case and the 3 to 2 adapter should be wired upstream of the RV's 7 pin trailer connecter regardless of trailer/car type being towed.

[gijoecam]

Maybe I'm mis-reading something... But the 7-pin connector is showing a left turn, a right turn, and BOTH when the brake is applied, right? There is (or should be) no separate BRAKE signal on a standard 7-pin adapter, and if there is, somebody has it wired wrong.

[mcewena]

enblethen wrote:
No, the adpater is built for standard connector wiring.
You need something like this one from Roadmaster.
Converter

Many thanks all!

[enblethen]

No, the adpater is built for standard connector wiring.
You need something like this one from Roadmaster.
Converter

[mcewena]

TubaPete wrote:
Sounds like your tow vehicle has seperate lights for turn and brake (amber and red, maybe). A 4 pin combines turn and brake into one light on each side. You need to install a wiring adapterin your vehicle to combine the two lights on eahc side into one. You can get it at almost any big box store, e.g. Walmart, that carries automotive supplies.

You mean the 7 to 4 doesn't include that function?

Thanks.

[mcewena]

TubaPete wrote:
Sounds like your tow vehicle has seperate lights for turn and brake (amber and red, maybe). A 4 pin combines turn and brake into one light on each side. You need to install a wiring adapterin your vehicle to combine the two lights on eahc side into one. You can get it at almost any big box store, e.g. Walmart, that carries automotive supplies.

MH brake and signal lights are separate. I have an led tester just like that and it reports things work as they should (although the back up light flashes slowly)

I have a 4 to 7 adapter like this http://www.amazon.com/Reese-Towpower-74607-Wiring-Adapter/dp/B000CPI6VI/ref=pd_sim_sbs_auto_3 and a 4 pin tester like this http://shop.trailerlightcheck.com/Vehicle-Wiring-Tester-LCV101.htm connected to it just to rule out the marker wiring.

[TubaPete]

Sounds like your tow vehicle has seperate lights for turn and brake (amber and red, maybe). A 4 pin combines turn and brake into one light on each side. You need to install a wiring adapterin your vehicle to combine the two lights on eahc side into one. You can get it at almost any big box store, e.g. Walmart, that carries automotive supplies.