Tail light fuse keeps blowing!

[RockOcean]

Hi ya'll been trying figure out why my tail light fuse keeps blowing.

I have an automatic SR5 with 280k on it. And have checked the following:


- All bulbs on that fuse
- Wiring going into the hatch
- Tow hitch wiring was removed 2 years ago
- Fuse box wiring
- All wiring behind dash and gear selector
- License Plate and Tail Light wiring
- Tail Light Relay

I have read the Tail light fuse keeps blowing? thread a number of times that info is not helping fix this issue.

I'm really at a loss and for the first time in a long long time can not fix something myself and have to take it some where. Any input on something I may have missed would be greatly appreciated.

It first did it 2 months ago and then went a whole month with out it blowing. Some times it will last 10 mins or so but most of the time it blows instantly as soon as the parking lights are turned on.

 

[spartacus]

Check inside the wire loom connected to the hatch.

 

[nissanh]

Check the trailer wiring harness connector. It is probably rusted/shorted.

 

[2TH4IST]

There is a sub harness on each tail light (bulbs to harness to gromet to interior connector). I had a issue with my right tail light that would blow fuses. I'd take a look there, unfortunately you do need to take both rear panels off to access the sub harness connectors.

 

[brillo_76]

Hi ya'll been trying figure out why my tail light fuse keeps blowing.

I have an automatic SR5 with 280k on it. And have checked the following:


- All bulbs on that fuse
- Wiring going into the hatch
- Tow hitch wiring was removed 2 years ago
- Fuse box wiring
- All wiring behind dash and gear selector
- License Plate and Tail Light wiring
- Tail Light Relay

I have read the Tail light fuse keeps blowing? thread a number of times that info is not helping fix this issue.

I'm really at a loss and for the first time in a long long time can not fix something myself and have to take it some where. Any input on something I may have missed would be greatly appreciated.

It first did it 2 months ago and then went a whole month with out it blowing. Some times it will last 10 mins or so but most of the time it blows instantly as soon as the parking lights are turned on.

You probably have a bare wire somewhere in this circuit. rubbed the insulation off and dead shorting to ground. Or a pinched wire where the insulation is broken shorting. That happened to be on the trailer hitch.

What happens when you disconnect the module for the hitch completely? Sometimes they can short internally too..

 

[phattyduck]

Time to start unplugging things and see when the fuse stops blowing. I'd start with the plug up in the ceiling near the hatch along with the each tail light. The gauge cluster is another possible culprit, though it can also be any of the interior backlight connections...

-Charlie

 

[RockOcean]

Just a friendly reminder as stated in the original post:

Tow hitch wiring was removed 2 years ago

 

[RockOcean]

Check inside the wire loom connected to the hatch.

This has been checked.

 

[RockOcean]

There is a sub harness on each tail light (bulbs to harness to gromet to interior connector). I had a issue with my right tail light that would blow fuses. I'd take a look there, unfortunately you do need to take both rear panels off to access the sub harness connectors.

This has been checked

 

[RockOcean]

You probably have a bare wire somewhere in this circuit. rubbed the insulation off and dead shorting to ground. Or a pinched wire where the insulation is broken shorting. That happened to be on the trailer hitch.

What happens when you disconnect the module for the hitch completely? Sometimes they can short internally too..

I will disconnect that and see thank you!

 

[RockOcean]

Time to start unplugging things and see when the fuse stops blowing. I'd start with the plug up in the ceiling near the hatch along with the each tail light. The gauge cluster is another possible culprit, though it can also be any of the interior backlight connections...

-Charlie

Good call! I will unplug the tail gate connector and see. I did check all of the interior back lights except for the cluster will also do that.

 

[RockOcean]

Hell yeah, thank you phattyduck!

I started by unplugging the tow hitch module and the fuse blew.

I then disconnect both the White and Gray connectors that go into the hatch. Boom fuse did not blow! (One trouble with diagnosing this has been that when the fuse first blew, it went a month with out blowing again.. Then was very random when it would blow) So I went for a quick spin and it held til I got back. I then plugged in the grey connector and the fuse blew - BINGO!

So I take it that it has to be the license plate light wires right? Pretty sure that is the only thing in the hatch on the tail light fuse? I don't have a helper right now so I don't know exactly what else the grey connector powers in the hatch.. But as long as I have taillights I really don't care about anything else for the time being.

Thank you all! Goes to show how multiple threads on the same topic can be beneficial. Is there anyway to merge threads or something like that?

 

[brillo_76]

Just a friendly reminder as stated in the original post:

Tow hitch wiring was removed 2 years ago

I thought you may have just removed the trailer hitch wiring to the hitch itself and left the module in place... As lots of aftermarkets modules connect to the passenger side instead of drivers side. When the drivers side modules fail. We cant get replacement driver side unless used somewhere. :-(

Glad you found it.

What year of 3rd gen are you working on? I didn't see it listed in this thread just its a sr5 v6

 

[2TH4IST]

License plate lights are on that connector. The connectors name is BR1 dark gray, pin #9, top roof left. On my 2000 that wire is green in color. It then goes to connector BS1, pin #9 green, dark gray connector by rear hatch control box. Then goes to connector L1 (bulb receptacle) pin #2 green. The white/black wire at bulb is ground, which goes back through connector BS1 (pin 3) BR1 (pin 3) and grounds at left quarter panel inner (BH).

Hope this helped.

 

[RockOcean]

I thought you may have just removed the trailer hitch wiring to the hitch itself and left the module in place... As lots of aftermarkets modules connect to the passenger side instead of drivers side. When the drivers side modules fail. We cant get replacement driver side unless used somewhere. :-(

Glad you found it.

What year of 3rd gen are you working on? I didn't see it listed in this thread just its a sr5 v6

It's a 1996.

 

[RockOcean]

License plate lights are on that connector. The connectors name is BR1 dark gray, pin #9, top roof left. On my 2000 that wire is green in color. It then goes to connector BS1, pin #9 green, dark gray connector by rear hatch control box. Then goes to connector L1 (bulb receptacle) pin #2 green. The white/black wire at bulb is ground, which goes back through connector BS1 (pin 3) BR1 (pin 3) and grounds at left quarter panel inner (BH).

Hope this helped.

Thanks for that info!

 

[RockOcean]

The bad wire was indeed going to the license plate lights. It got damaged where the wire loom attaches to the drivers side lower part of the hatch via a tie-wrap.

 

[brillo_76]

Glad you isolated to the exact location. I haven't seen a lot of these wires damaged inside doors and hatches yet. I seen a lot of folks have issues with them in the drivers door jam and rear hatch jams. Just out of curiosity does it l looked like some damage it working in the past or did it just wear out from vibrating or rubbing against something. Mostly, if not messed with the factory wiring only gets damaged where it moves around a lot However, I have seen really crappy wiring repairs that damage other wires by not fixing things correctly so wires do not rub together anymore. As well as rodent damage... Hopefully, this repair will forever solve your tail light fuse issues.

 

[RockOcean]

Glad you isolated to the exact location. I haven't seen a lot of these wires damaged inside doors and hatches yet. I seen a lot of folks have issues with them in the drivers door jam and rear hatch jams. Just out of curiosity does it l looked like some damage it working in the past or did it just wear out from vibrating or rubbing against something. Mostly, if not messed with the factory wiring only gets damaged where it moves around a lot However, I have seen really crappy wiring repairs that damage other wires by not fixing things correctly so wires do not rub together anymore. As well as rodent damage... Hopefully, this repair will forever solve your tail light fuse issues.

I would say that the tie-wrap was not cinched down enough so over the past 300k miles the wire loom was slowly rubbing away and that wire was on the outer corner so it was the one to go. If the tie wrap was cinched down more as to not let it move at all I think it would have lasted longer.

 

[brillo_76]

I would say that the tie-wrap was not cinched down enough so over the past 300k miles the wire loom was slowly rubbing away and that wire was on the outer corner so it was the one to go. If the tie wrap was cinched down more as to not let it move at all I think it would have lasted longer.

Interesting.. I have a few over 300K. I haven't seen that one yet. Might be a factory mistake without the tie wrap not tight enough. Next time I am in a rear hatch I will look at my wire looms. I don't recall anyone else ever having reporting this on the forum here that I can recall at least since 2015 anyways. Most likely why you couldn't find it. However, since you shared the experience. That information will hopefully help others.

Also the tailgate circuit changes in 1999 all the EWD diagrams. 1996-1998 the wire goes directory from the turn on switch to the relay on the Red white wire. From 1999 to 2002 the red white wire from switch goes to the combination meter then it color changes to red green wire then to the body ECU and then to the relay. The rest of the circuit wires all stay the same across entire generation. This is why I was wondering the year of the rig.

Thanks for the feedback.