Trailer Lights - Help Appreciated!

Boiler_Up · 04-11-2019, 07:41 AM

I will be calling the RV Dealership today, but I would rather not drive an hour each way to get this resolved.

I have a 2019 2100BH. When I went to pick it up at the dealership I had a wiring harness problem with the TV. They messed with the TT rear tail lights for quite some time to get it to work until we realized it was my TV issue. When I came back with my TV wiring working we hooked it up during the day and everything seemed to be working.

I just tested it with a buddies truck and here is where I currently stand:

1. Auto Lights on during the day = no headlights, just running lights. The trailer functions normally it seems (although dim braking and turn lights I think). Turn signals, braking, etc. tested.

2. Turn ON the headlights for the TV and the TT running lights remain on just like #1, BUT the brake lights remain ON like they are in full brake mode only really bright. If I turn on a turn signal, I can BARELY see it flickering almost like you can see its trying to function but its being overridden by the brake signal thats being sent.

I would say I would be concerned its my vehicle wiring harness, but this is exactly what happens on my buddies TV when he hooks up to it.

Easy fix? Or am I destined for another half day wasted trip to the dealership... or possibly having to leave it there for extended stay?

Wingchop · 04-11-2019, 09:55 AM

The first thing I always check with 12v systems is to make sure you have a good ground connection on both the TV and TT, a bad ground can give you all kind of weird results.

The second thing I'd do is get a 12V trouble light and check your TV connector and make sure its wired correctly, very cheap and easy to do.

If both of those steps don't solve the problem, then you know the TT has a wiring problem.

BobC · 04-11-2019, 10:32 AM

Quote:

Originally Posted by Wingchop

The first thing I always check with 12v systems is to make sure you have a good ground connection on both the TV and TT, a bad ground can give you all kind of weird results.

The second thing I'd do is get a 12V trouble light and check your TV connector and make sure its wired correctly, very cheap and easy to do.

If both of those steps don't solve the problem, then you know the TT has a wiring problem.

Alternatively, if you have a friend with a TV and/or TT that are known to work properly, you can switch around in order to determine if you have a TV or TT issue.

Boiler_Up · 04-11-2019, 10:33 AM

So I did purchase the Curt 7-Pin wiring tester. Unfortunately it does not function on the BMW because of some overly complicated lighting system. I DID however, test my buddies truck and it seemed to be functioning just fine. (this is the truck I tested with and the TT exhibited the same issues as it did with mine)

I have no idea where to start looking for grounding issues. I could open up the trailer lights they had open to see any obvious signs of grounding. Otherwise I guess I have no other choice than to take it back to the dealer.

Sigh..

BobC · 04-11-2019, 05:46 PM

Sorry about the unnecessary mention about trying a friend's truck. I'd read your posting earlier in the morning and responded with my first response without re-reading your post.

If it's a bad ground, the primary suspect is the main ground connection. It could either be a bad connection between your TT's electrical cable and the frame or it could be a fault within the cord itself. The first thing I would do is to disconnect the cable from the frame, clean everything and re-connect. If that fixes things, you're good. If not, check the cable itself for continuity between the plug's ground pin and the frame with a multi-meter. A cable issue could explain why things worked and then didn't work since the problem could come and go as the cable flexes (so flex it as you test it). I don't know how or where your cable ends are connected to the trailer wiring but, if you can get to it, check all the cable wire ends to their corresponding plug pins.

If the above all checks out, you're going to have to open up your tail lights and start checking everything there with a multimeter. However, the first thing I'd do is to remove and re-set each bulb to make sure that isn't the problem. Tail lights can be wired in some confusing ways so work methodically.

Good luck.

MainelyScott · 06-16-2019, 07:39 AM

Quote:

Originally Posted by Boiler_Up

I will be calling the RV Dealership today, but I would rather not drive an hour each way to get this resolved.

I have a 2019 2100BH. When I went to pick it up at the dealership I had a wiring harness problem with the TV. They messed with the TT rear tail lights for quite some time to get it to work until we realized it was my TV issue. When I came back with my TV wiring working we hooked it up during the day and everything seemed to be working.

I just tested it with a buddies truck and here is where I currently stand:

1. Auto Lights on during the day = no headlights, just running lights. The trailer functions normally it seems (although dim braking and turn lights I think). Turn signals, braking, etc. tested.

2. Turn ON the headlights for the TV and the TT running lights remain on just like #1, BUT the brake lights remain ON like they are in full brake mode only really bright. If I turn on a turn signal, I can BARELY see it flickering almost like you can see its trying to function but its being overridden by the brake signal thats being sent.

I would say I would be concerned its my vehicle wiring harness, but this is exactly what happens on my buddies TV when he hooks up to it.

Easy fix? Or am I destined for another half day wasted trip to the dealership... or possibly having to leave it there for extended stay?

I just had this happen on mine ( due to me fiddling around with the taillights trying to add a center brake light) I had inadvertently switched the two wires on the taillights, I have bulbs on mine. One filament is for the brake/turn signal the other for running. I suspect that with the guys fiddling around they got the wires switched.

golden13 · 06-24-2019, 12:26 AM

What the heck is a "TV?" I thought for a minute you were talking about your television!

BobC · 06-24-2019, 11:30 AM

Quote:

Originally Posted by golden13

What the heck is a "TV?" I thought for a minute you were talking about your television!

Tow Vehicle

golden13 · 06-24-2019, 11:38 AM

LOL! I guess it was obvious, but not to me! Just curious, maybe you know the answer.

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