Trailer running lights on Sequoia not working - brake/signals do

[pjwalleye1]

My trailer brake/signal lights work but running lights do not. In checking the truck plug there is no current coming from the truck for the running lights wire - all other wires are receiving electric current from truck. Ground is fine.

Is there a fuse on the vehicle specifically providing current to the running light plug that may have tripped or do I have to take this to dealer?

Thanks for any advice!

[Nick Kuhn]

Could be some damage to the running light wire prior to the connector on the truck. Check the voltage and not the current. If you are seeing voltage at the plug but no current, then there is an open circuit on the trailer. If you are not seeing voltage at the plug then there is either an open circuit or a short in the truck wiring.

[Jim Almquist]

I had the same problem on my 4Runner and it was a fuse under the hood. I first looked at the fuse panel inside the truck thinking that is were it would be and when they all checked out I thought it must be the trailer but that tested good as well. The fuse will only affect the running lights at the trailer plugin and not the actual running lights.

[Whisker Trout Slayer]

I have the same problems as well. I have a Chevy truck and there is a fuse under the hood. I changed it and it blew about 1 mile down the road. I need to fidn out why is it blowing.

I am thinking of changing the fuse and then hooking up to my brother in laws snowmobile trailer and towing it around some early evening and see if it blows again.

If it does where do I look at on my truck?

If it doesn't I know I have to look somewhere on my boat trailer but where?

Any help is appreciated as I know nothing about trailer wiring and circuitry and that type of elecrtical stuff.

[SkunkedAgain]

In my experience, 90% of the time it is a grounding issue. If you have gone through and determined that it is not a grounding issue, then you are likely wrong!

A bad ground will cause lots to work incorrectly (blink opposite), lights not to work, and fuses to blow.

[Jim Almquist]

WTS make sure to try that other trailer before you start tearing things apart. If it test OK then you will know that the wiring in your trailer is the problem and you can go from there. It is easier to replace the whole wiring harness sometimes then it is to find the problem but the very first thing to do is make sure the white wire that is your ground on your trailer has a good clean connection to the frame.

[shizzy]

I had the same issue on my Ranger. It was also a fuse under the hood. Mine was labled "tow/haul"

[Jeremy airjer W]

Bad grounds don't generally cause fuses to blow.

PJ, you can check your owners manual for the tow fuse locations. If you don't have one they are available in PDF form from the Toyota HSOforum. If there is no power on the pin for the connector than the fuses are the first place I would start looking.

[Dale_Gribble]

Im experiencing this with my F150 also, checked the fuses, not them. Gona rewire the trailer anyway because its a mess, ill let you guys know if i find anything in the truck thats causing it.

[LightningBG]

I've had this problem a couple times. Always ended up being a fuse.

Mine is under the back seat in the envoy.

[SkunkedAgain]

So what does replacing the fuse do if you don't get to the bottom of what caused the fuse to blow in the first place? I'm with most of you that the fuse is likely blown, but he's gonna keep blowing them unless he finds the underlying problem.

[Jim Almquist]

Blowing the fuse is usually caused by some type of short to ground. In my case my trailer seemed fine because I never had a problem with either my Suburban or my Tundra when backing my boat into the water but my 4Runner would blow the running light fuse to the trailer. Now I just unplug the light to save a fuse. Why the other 2 trucks would have no problem is beyond me.

[LightningBG]

So what does replacing the fuse do if you don't get to the bottom of what caused the fuse to blow in the first place? I'm with most of you that the fuse is likely blown, but he's gonna keep blowing them unless he finds the underlying problem.

Very true. For Pjwalleye it seems like a one time or 1st time deal, so the fuse is where I would look.

For Whisker, there is something else that is causing it to blow, could be a lot of things.

I'm no expert, but I am a tinkerer. These are the steps I would take, but I cant say they are the "proper" steps.

1. Try another trailer that you know works. (borrow one)

2. Test the plug (may be a moot step, but I'd do it)

3. Depending on what type of trailer, I'd rewire. A big boat trailer or ice house is going to be a pain, a small utility trailer, sled trailer, or little boat triler isn't too bad. Wiring kit cost about $20.

4. Replace lights themselves.

In my experience, if items are replaceable, its cheaper to just replace them than having an "expert" try to track down the problem spot.

[delcecchi]

In the case of a boat trailer one might be able to find the suspected problem by looking at the wires all over the trailer. If they go into a tube, look where they go in. If you connect a multimeter on the resistance scale (R x 1) from the hot wire to ground and go around wiggling and pulling on wires and watch for a change you just might find it.

Worth a try anyway.

[Big Buck Buster]

In the case of a boat trailer one might be able to find the suspected problem by looking at the wires all over the trailer. If they go into a tube, look where they go in. If you connect a multimeter on the resistance scale (R x 1) from the hot wire to ground and go around wiggling and pulling on wires and watch for a change you just might find it.

Worth a try anyway.

This will work, but you have to have all the lights disconnected from the circuit. With the lights connected, you will get a resistance reading from all the bulbs.

[SkunkedAgain]

I usually find that there is a hinge point, a pinch spot, or a hole where the wires have rubbed the frame enough to get through the insulation and cause a short via contact with the trailer frame. Sometimes it's even a mouse that chewed on a section of the wire hidden in the trailer frame.

[Xplorer]

pjW/WTS,

On my '10 tundra the fuse for the taillights is under the hood, and is called "tow tail" on the diagram on the underside of the fusebox cover. It is a 30 amp low-profile mini fuse.

[Jeremy airjer W]

but if the resistance goes up while you wiggle the wires the short to ground has been removed. If the resistance goes down when you wiggle the wires the short has occurred.

[pjwalleye1]

Found the blown fuse in the engine area - there were 3 blocks of fuses and a 'tow running lights' 30 fuse was indeed blown! Thanks for everyone's input!

[shizzy]

So what does replacing the fuse do if you don't get to the bottom of what caused the fuse to blow in the first place? I'm with most of you that the fuse is likely blown, but he's gonna keep blowing them unless he finds the underlying problem.

I replaced the blown fuse on my truck three years ago and it hasnt blown since. it is possible a P.O. was hooked to a lousy trailer and popped it.

[Whisker Trout Slayer]

I have switched the fuse twice and it still blows about 5 minutes down the road.

[Jeremy airjer W]

If it blows with your trailer attached than you need to start looking at the wiring on your trailer.

[chris63]

If you do allot of trailering (especially down bumpy washboard dirt roads)you should check ALL your wiring on your trailer.Sounds like you have a frayed wire shorting to ground which in turn blows the fuse on your truck.c63