trailer wiring

I just wired up my trailer hitch and wanted to add a new thread about this. I did a search and only found one post that was VERY helpful.

Here it is....

http://forums.tdiclub.com/showthread.php?t=143774&highlight=trailer+wiring

Basically, just buy a modulite module from etrailer.com, then connect up the wires as follows:

wire grey/black to brown tail line on modulite
white/black to the left turn on modulite
green/black to the right turn on modulite.
12V from plug in trunk (dark wire) to power on modulite
connect the ground from the modulte to one of the taillight bolts
***Leave the brake wire unconnected

Everything works great. Nothing is dim.

Thanks for this! I will be doing mine soon.

Thanks to user "artificer" for doing all the leg work!!!

BTW - I connected everything up on the left side since that is where I could get to all the wires except 12V. I just ran a separate 12V line from the power plug on the right over to the modulite on the left.

Bump!

I wired mine up last night like it says here. I put a plug though between the car and the modulite so that it can be removed when not being used. The plug tucks into the brake light access panel so it is hidden when the modulite is not installed. I installed it in the passenger side brake access, and it draws 12V from the power socket on that side.

Bump! Dead links

Keven said:

Bump! Dead links

Click to expand...

Type "etrailer modulite" into the google search field, then hit the seach button.

Over to the other thread ...

http://forums.tdiclub.com/showthread.php?t=143774

Just purchased a modulite (w/pwm) from etrailer and installed it per instructions above. Brake and turn signals work fine until I turn on the running lights. Then the trailer lights are on full and hitting the brakes or turn signals has no effect. I think this is because the modulator can't see the difference between the 2.7 volts that powers the running lights and the 12 volts used for brakes and turns (gives the trailer lights full brightness from either singal). Because the tail lights are powered over the same wires as the turn signals I can't figure out a way around this problem.

I have not seen this issue addressed in the many threads on this topic and am wondering if anyone has any insight or if there's something I'm not getting.

thanks

John

It is possible that you are the first one to have bought the PWM-capable Modulite and reported on results. You are having the problem that I suspected would happen all along.

If your trailer has no lighting on the "Brown" wire other than the left and right taillight housings themselves, just wire it up the way I did it (and documented in the other thread). No Modulite no signal converter no nothing. Signal to outer left bulb and outer right bulbs go to green / yellow on the trailer connector (I've forgotten which is left or right), white trailer connector wire goes to ground, brown goes to nothing.

jrone said:

Just purchased a modulite (w/pwm) from etrailer and installed it per instructions above. Brake and turn signals work fine until I turn on the running lights. Then the trailer lights are on full and hitting the brakes or turn signals has no effect.
John

Click to expand...

What module did you buy? Is there a separate wire for the parking lights? Are you wiring it up for 2 wire or 3 wire?

Michael

I have the same problem mentioned by jrone. My trailer has side marker lights, and I'm not sure if I need to do something about that (one post said something about cutting a wire on the trailer?).
Any help or direction to more information would be greatly appreciated.

karltinsly said:

I have the same problem mentioned by jrone. My trailer has side marker lights, and I'm not sure if I need to do something about that (one post said something about cutting a wire on the trailer?).
Any help or direction to more information would be greatly appreciated.

Click to expand...

-Karl,

What's the part number of the Modulite module that you purchased? The newest one, "Upgraded Protected Modulite Kit - 119176" should get these voltage issues right.

-darren

According to my receipt, I got the 119190 kit, which includes the 119190 harness. It's the one they list for the 2009 Jetta. Do you think I got the wrong one? I might just need to hook it up differently, though no time to do that until Friday.

Hmm. I also did not ground the brake wire -- just didn't hook it up. Could that be the problem? The post I was using as a guide just said don't hook it up.

The 119190 appears to be the same as the 119176 but it can handle more current (presumably a good thing) so I think you are OK on that.

What do you mean by "did not ground the brake wire?" I'm looking at the diagram for the 119190 and it shows a single ground which must be hooked up or you would be getting nothing. Are you referring to the hot lead for the brake light? You will definitely need that and without it you won't get brake lights.

To avoid confusion, should you be reading older threads on this subject -- The trouble that folks had with prior generations of Jettas was caused by the fact that the brake and running light use the same bulb.

Our cars have discreet brake and running lights, so the only issue we have to be concerned about is the fact that the CECM sends just enough current to light the bulb, not enough to light a trailer bulb as well. If the current draw goes too high or low the dash will warn you of a burned out light.

The Modulite module passively senses for current on the wires and triggers a relay to direct voltage from somewhere else (in my case, the 12V socket in the rear) to the correct trailer lights.

Hope this helps!

-darren

karltinsly said:

Hmm. I also did not ground the brake wire -- just didn't hook it up. Could that be the problem? The post I was using as a guide just said don't hook it up.

Click to expand...

The other post is based on an older, non-PWM module. The one you have is more advanced. I've never seen the wiring on a 2009 Jetta, so you have to help me out a bit if you want my help.

What bulbs/filaments do the turn/brake/parking lights go to?

As an example: my 2006 Jetta has marker lights that go full on when the parking light is on. The turn bulb filaments are also used as low voltage parking lights, turn and brake.

If I was going to connect this module up to my trailer, I would try just the turn signals, and ground the brake light. If the low voltage turned on the trailer parking/perimeter lights dimly, I would ground the brown as well. If it didn't turn on the parking lights, I would connect the brown to the cars marker lights.

Clipping the trailer lights: I would suggest that you don't do it. Depending on how the module works, the main lights will all be using the same filament. The perimeter lights should still be controlled by the parking light circuit of the trailers wiring. This is a guess, since I don't have the module, and the instructions are... brief. More lights are never a bad thing.

Michael

darren:

looks like I started posting just as you did. The "ground the brake light" is from the modules instructions. If the same filament is used for turn/brake, you don't want to use the brake signal input into the module, so you ground it. On mine, I just didn't connect it with the old module.

On my 2006 Jetta, the same filament handles parking, turn, and brake signal. This module will convert that to the standard everything on its own filament of most trailers. If you ground the red brake input and brown parking input, it still might send the signals, but only on one filament of each rear turn light. Not sure, since I don't have the module, or the newer car.

Michael

artificer said:

darren:

looks like I started posting just as you did. The "ground the brake light" is from the modules instructions. If the same filament is used for turn/brake, you don't want to use the brake signal input into the module, so you ground it. On mine, I just didn't connect it with the old module.
[..]
Michael

Click to expand...

Gotcha, then Karl has been following the wiring instructions for previous generation of Jettas (and perhaps current sedans -- I don't know) that use a combined taillight/brakelight. In the JSW they are discreet and the brake wire definitely needs to be hooked up (to either side).

Thanks for the help, Michael!

-darren

Thanks, Darren and artificer. I understand better now about how the modulite works. Do you know which wires I need to hook up to in my car, then?

karltinsly said:

Thanks, Darren and artificer. I understand better now about how the modulite works. Do you know which wires I need to hook up to in my car, then?

Click to expand...

Here are my scribbles made at the time of install:

From driver's side taillight
Brake: black/red (2nd from top) to Modulite Red
Left Turn: black/white (2nd from bottom) to Modulite Yellow
Running Lights: grey/black (top) to Modulite Brown

From passenger's side taillight
Right Turn: black/green (2nd from bottom) to Modulite Green

From passenger's side 12V power
black/red to Modulite "fat" red wire (battery+)

And obviously ground it to one of the Jetta ground points -- they are everywhere which is pretty cool.

No promise that this is mistake free. The kit from eTrailer came with a wire tester so you might want to use it. That said, I am pretty sure that this worked on the first try.

Good luck!

-darren

Thanks, Darren -- that should be a big help. I'll let you know how it goes when I get a chance to fix the wiring on Friday.

I still need to run the brake wires from the front before I can actually try towing my trailer, but it will be good to get the lights working.

After much mind-puzzling and knuckle-banging, I have finally gotten all the wires run (to the cockpit fusebox) and the brake controller mounted. Just have to hook everything up. One question -- where do I hook up for the brake signal to the controller? I don't see a switch attached to the pedal (its probably higher up than I can see). Any recommendations on where to get the brake signal? Thanks!

karltinsly said:

One question -- where do I hook up for the brake signal to the controller? I don't see a switch attached to the pedal (its probably higher up than I can see). Any recommendations on where to get the brake signal? Thanks!

Click to expand...

I would have thought that the brake controller would be designed to trigger off the brake light. Trailers with brake controllers on the trailer do. What do the installation instructions suggest? Can you post a model number for this controller so that I can look up the wiring diagram?

Thanks!

-darren

p.s. - I'm looking forward to seeing your Bosal towbar installation photos!

Yes, I ended up triggering it with the brake light. The installation kit I bought came with a two-conductor cable that I ran from the back to the fuse box. I used one wire for the brake power, and the other I spliced into the brake light wire going into the Modulite to trigger the controller. Towed the trailer around the block a couple of times. Works like a charm.
I look forward to putting up the hitch install pics soon!

I'm glad it worked. What will you be pulling with this?

-darren

A Fleetwood Cobalt popup camper. They're made by Coleman now -- you can check it out at http://www.colemantrailers.com/cobalt. Loaded weight is around 1500 lbs. I'll probably buy a utility trailer eventually too, since I'll be getting rid of my 1998 Explorer altogether. Still need to be able to haul the occasional piece of furniture or large appliance.

Sweet - that's camping in style!

-darren

Here's a link to my web album with the pics. It looks like I will have to upload each pic individually if I use the photo functionality here on TDIClub, is that correct?

http://picasaweb.google.com/karltinsly/DropBox?authkey=8UWElz7fYBY&feat=directlink

Funny, when I was editing those pics, I realized I didn't have any pics of the installing of the hitch frame. Oh well, those are covered pretty extensively in the other thread.

Karl,

Awesome job with the photos. Thanks for the annotations too! You might want to add some photos of the towball mounted and something showing how it mounts. It probably deserves its own thread, too since no-one has posted photos of the Bosal mount on a JSW yet.

IMHO, it's easier to see what's going on with a non-black chassis. The parts stand out a lot better than in my photos.

BTW: Where did you route your wires from the front to the back of the car?

-darren