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Discussion Starter · #1 ·
Does anybody know of a fuse or relay that controls one side of the trailer wiring on an 05? The truck lights are OK, it's just the trailer connector that has no power. I have the BT package, so the wiring is all factory. My little trailer seems to have developed some kind of wiring problem, after a long trip after dark, the 10A fuse for the running lights is often blown. After the last time I took it out, the left turn doesn't work. It did before towing, I always check the lights.
 

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I have an 06 and there are 2 relayas under the hood on the pass side. I would check them.
 

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Your problem sounds like the wiring on your trailer is bad. That is the only reason the 10 amp fuse would blow. But you need to check this recall to see if your truck is included:

http://www.nissanhelp.com/Recalls/Titan/2005.htm

If you have bad trailer wiring it could have damaged your BCM. This recall will give additional fuse protection to stop that problem.
If your truck is included in this recall take it to the dealer for the fix, but you still need to check out your trailer wiring. I think you have a problem there.
 

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SHIFT_I did it the hard way... I earned it.
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Towing a trailer this weekend I had a similar problem. Same issue with the lights, but no fuses blown. I had the tow hitch wiring recall done several weeks ago. Wonder if something got screwed up doing that?
 

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I have the same problem towing my boat after I let the dealer talk me into buying the relays for the trailer lights,I didn't have the tow package before I did that and I had no problems at all with my lights. The tech told me that my lights should not working without the relay's but they were.I would check my lights before we hit the road and everything was fine. I forgot to disconnect the harness before putting my boat in and blew something and every since then I've had problems with my trailer lights. I would turn the truck lights on and everything would die. Turn the lights off and I would have brakes and signals, but no running lights. I took it to the dealer and they told me that I needed the relays in order to have lights. They put in the relays and did the recall on the BCM. They thought that that was the problem but somehow it reversed itself. I would have running lights and no brakes or signals . They replaced the BCM harness and the BCM and it still didn't work. So they ordered another BCM and asked me to leave my truck so that they could troubleshoot my system. While the truck was there I had them to install the brake controller so that I would have it when I needed it. I go to pick my truck up and the BCM wasn't replaced because thier computer was broken. Needless to say I'm still haveing problems with the lights.
 

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LDOTITAN said:
Towing a trailer this weekend I had a similar problem. Same issue with the lights, but no fuses blown. I had the tow hitch wiring recall done several weeks ago. Wonder if something got screwed up doing that?
There are added fuses in the harness that is installed when you have the recall done. Look for blown fuses there. However, if fuses are blowing that means you have a problem with the trailer wiring.
 

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I lost the right turn/stop on my trailer. I checked the signal at the 7 way plug on the truck and nothing there either. I then checked the fuses and nothing was blown so I had to take it to the dealer. It turns out that if you have the BCM wiring harness put in from the recall that there are some fuses in that harness mess and that is what blew on me.
 

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I am currently having the same problem, no blown fuses. I did just have a new B C M installed at the dealer and after reading the service manual it says that the BCM controls the trailer wiring signals. Crazy! I am taking it to the dealer cuz it sounds like their problem..
 

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scr38 said:
There are added fuses in the harness that is installed when you have the recall done. Look for blown fuses there. However, if fuses are blowing that means you have a problem with the trailer wiring.
Any way to show me where in the box these would be? I wouldn't be able to tell the new fuses from the old ones.
 

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LDOTITAN said:
Any way to show me where in the box these would be? I wouldn't be able to tell the new fuses from the old ones.
The added fuses aren't in a box. They are in the added wiring harness that plugs into the BCM. This harness should be secured with a wire tie next to the BCM. The fuses are in a inline fuse holder in the harness.
NOTE: This harness with fuses is present only in vehicles that have had the trailer wiring recall done. See attachment for location of the BCM. It is above the accelerator pedal.
 

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SHIFT_I did it the hard way... I earned it.
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scr38 said:
The added fuses aren't in a box. They are in the added wiring harness that plugs into the BCM. This harness should be secured with a wire tie next to the BCM. The fuses are in a inline fuse holder in the harness.
NOTE: This harness with fuses is present only in vehicles that have had the trailer wiring recall done. See attachment for location of the BCM. It is above the accelerator pedal.
I'll check this out. Thanks.
 

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Discussion Starter · #15 ·
I guess that I'm not the only one with weird trailer light problems. Like I said in my post, I suspect there's a wiring problem with one of my trailers and that's why it blows the 10A fuse under the hood. I just haven't had a problem with the brake lights before. The little trailer with the wiring problem is a small flatbed and you can see the truck's taillights, but my toyhauler is wider than the truck and I don't like the idea of running without all of the brakes and turn signals working. I have read that the 06 models have a separate relay for the left and right sides of the trailer, but I don't know if the 05 do something similar. It sounds like the "upgrade" is to add more fuses in obscure places of the wiring harness, but I expect that I will contact the dealer about it, thanks for the info scr38.
 

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I have done some research this morning on the trailer wiring recall and changes in the 06 Nissans.
I stated in posts above that there are added fuses in the harness that was added in the recall. I now think that is NOT correct. I was told in the past that there were fuses in the added harness, but I talked with a Nissan parts man and two techs this morning and they say that there are no fuses in that added harness. The harness contains relays and diodes, which prevent feedback (which could damage the BCM) to the BCM from trailers that are wired improperly.
On 04 and 05 models with Big Tow the turn signals were controlled directly from the BCM. There was a relay in the box under the hood that provided power for running lights to the trailer, and a second relay that provided 12 volt power for the trailer (to power 12 volt devices on a travel trailer). There was a 10 amp fuse for the trailer running lights in this box. If you had a non Big Tow vehicle and added the hitch and trailer wiring you had to add the two relays to provide running lights and power to the trailer.
This changed for the 06 models. They don't have the added harness at the BCM. The circuits were redesigned. There are now three relays in the box under the hood for the trailer. One for the 12 volt power, one for left turn and one for right turn. The 10 amp fuse for the running lights is still there. This redesign solves the feedback problem due to incorrect trailer wiring without having to install the added harness at the BCM.
Our trucks' trailer plug is wired to the RV standard. This is not the same as some non RV commerical trailer wiring. The function of each pin is on the cover of the trailer socket. Check to be sure your trailer is wired the same way.
I hope this may help with some of the trailer wiring problems.
 

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I understand everything you said scr38 and I thank you for that information, but in my case I had running lights,turn signals and brakes on my truck and I didn't have the big tow package nor did I have the relays installed. The tech at the dealership didn't believe me until I had my wife tell him that she was standing there telling me that I had l/r signals,brakes and running lights as she would let me know if the trailer lights were working properly. They've gone over my truck with a fine tooth comb and they still can not tell me anything as far as why after the relays were installed am I having the problems that I'm haveing with the trailer lights. I even had them install a brake control module thinking that that would cure the problem but it didn't and I'm trying to find the time to take the truck in to have them troubleshoot the system again and also replace the BCM again. I use my truck for work so I just can't drop it off for a day,but eventually I'll get the time and I'll let you guys know the outcome.
 

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05Titanman said:
I understand everything you said scr38 and I thank you for that information, but in my case I had running lights,turn signals and brakes on my truck and I didn't have the big tow package nor did I have the relays installed. The tech at the dealership didn't believe me until I had my wife tell him that she was standing there telling me that I had l/r signals,brakes and running lights as she would let me know if the trailer lights were working properly. They've gone over my truck with a fine tooth comb and they still can not tell me anything as far as why after the relays were installed am I having the problems that I'm haveing with the trailer lights. I even had them install a brake control module thinking that that would cure the problem but it didn't and I'm trying to find the time to take the truck in to have them troubleshoot the system again and also replace the BCM again. I use my truck for work so I just can't drop it off for a day,but eventually I'll get the time and I'll let you guys know the outcome.
I don't know what hitch you added since you didn't have the Big Tow package. I also don't know what trailer socket you used or where it was wired in. But if you bought the Nissan socket and the short harness that attached to the existing trailer harness; and wired the trailer according to the pinout on the Nissan socket cover, you would have stop lights and turn signals but no running lights. The socket pin for the running lights has no power to it until you add the relay.
 

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Discussion Starter · #19 ·
Had it in to the dealer to fix the problem. A fuse was blown in the BCM auxiliary wiring harness, under the dash, on top of the steering coulmn. Probably the first place I should have looked for a fuse. Next time something goes out, I'll probably want to have the tires dismounted to check for a fuse there.
 

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Those two new fuses are in a bundle with a ty-rap around it. They are under the dash on the drivers side by the BCM. You would think the dealer would alert you to this after they do the recall work.
 
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