trailer lights

rogerhrt · 06-28-2009, 04:22 PM

I have a 2004 Titan with tow package. I tow a tent trailer which all of a sudden one side of my lights dont work ( turn signal,brake,etc.) My lights work just fine in the truck. Problem is the tent trailer only, and just one side. Running lights and other turn signal, brake etc work fine. Someone told me there is a fuse for for each side in the truck . Does anyone know if this is true and if so where they are and which one . Ive found the fuses in the truck and relays under the hood with one fuse.
Thanks for any help, Roger

**loufish** · 06-28-2009, 09:51 PM

The turn/brake lights for the trailer are run by the Body computer, which because of a popular TSB years ago should have a sub-harness installed at the computer. This sub-harness has 2 fuses, one left and one right.

Do a search, there threads which have a few pics that will help...

Smokinnitro · 06-29-2009, 08:40 AM

Check out this thread should get you fixed up

Trailer Lights and Wiring Harness

Fairgame53 · 07-12-2009, 06:27 AM

Man, I thought you guys had me on the right track with fuses and relays, but nope. I've replaced my towing relay, the Jideco brand brown relay that controls the tow plug. The blue relays indicate they control turn signals which i have as well as brake lights. There are two fuses in the relay box by the battery and they are both good to go. I've done all the test light and ohms meter stuff and can't get power to JUST the running lights AND the pos/neg terminals in the tow plug. It's gotta be simple--just not for me!

**loufish** · 07-12-2009, 09:33 AM

Here we go....again......

The BCM runs the trailer turn/brake lights left & right. IF your truck has had the TSB completed there will be a sub harness located right next to the BCM(above the brake pedal area)that contains fuses for the left/right signals(trailer only, not the truck itself)those fuses need to be checked.

If both fuses are good, then you need to check each one for power when hitting the brakes. If there's no power to one of them then either theres a wiring issue(sub harness wire or sub pin bad) or the BCM is bad.
If you truck does NOT have the sub harness, you will need to check the 2 wires coming out of it for power like above.

This is only after double checking you have no lights at the 7 pin connector

You had all the lights at one time, so there's no missing relay.....AND relays rarely go bad compared to fuses...

**loufish** · 07-12-2009, 09:46 AM

Quote:

Man, I thought you guys had me on the right track with fuses and relays, but nope. I've replaced my towing relay, the Jideco brand brown relay that controls the tow plug. The blue relays indicate they control turn signals which i have as well as brake lights. There are two fuses in the relay box by the battery and they are both good to go. I've done all the test light and ohms meter stuff and can't get power to JUST the running lights AND the pos/neg terminals in the tow plug. It's gotta be simple--just not for me!

Just re-read your post.....Your killing me here!

Now it's just the running lights that don't work?

Quote:

Problem is the tent trailer only, and just one side. Running lights and other turn signal, brake etc work fine.

Here the running lights work fine.....So you lost ALL the lights on one side of the trailer - No running, turn, or brake?

And you checked for power for each pin at the 7 pin connector?....If you don't know that one of the 7 pins are the ground circuit....step away from the truck & get some help...

Blitz · 07-15-2009, 01:05 AM

This must be the day for this problem......

I went to pick up a car hauler today and got everything connected - no lights on trailer. 2004 CC SE.

I did find that the 10A fuse under the hood was blown. Fixed it - no better. This was the first time I have tried to tow anything.

I came home and searched the forums. Here's the scoop:

I have the TSB related fuses under the dash by the BCM. They are good.
I have all the relays needed
The running lights are working. There is 12V at the trailer plug.
No brake lights, no turn signals.

I don't know else to look. I've checked every fuse.

The truck does not have a brake controller installed, but I found the plug for it behind the dash. Is the brake controller necessary for the lights to function?

One of the posts above said to press the brake to see if the 2 fuses by the BCM power up. Mine are hot all the time.....

Help.

mjw357 · 07-15-2009, 05:16 AM

Quote:

Originally Posted by loufish

Just re-read your post.....Your killing me here!

Now it's just the running lights that don't work?

Look again, Lou, not the same guy posting.

**loufish** · 07-15-2009, 06:21 AM

Quote:

Look again, Lou, not the same guy posting.

Aw...man.....your so right...

..........but he's still killing me!

Quote:

I don't know else to look. I've checked every fuse.

Go back to those 2 BCM fuses and check that you have turn/brake voltage there...If yes, then take apart the 7 pin connector and find the corroded/damaged wires...

If you have nothing at the fuses, then double check the sub-harness at the BCM...if still good, you BCM is bad...

Didn't I just write almost the same thing a little while ago...

Blitz · 07-15-2009, 07:24 AM

Quote:

Originally Posted by loufish

Go back to those 2 BCM fuses and check that you have turn/brake voltage there...If yes, then take apart the 7 pin connector and find the corroded/damaged wires...

If you have nothing at the fuses, then double check the sub-harness at the BCM...if still good, you BCM is bad...

I've disassembled and cleaned the harness to no effect.

As I said, the 2 fuses at the BCM have constant power. It makes no difference if the signals are on or the brake is pressed....

**loufish** · 07-15-2009, 08:55 PM

If you are checking the correct fuses, and they're always "hot" the BCM is bad....