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Well, the tail light housings need to be grounded. If these are mounted in the truck bed then grounding the truck bed will enable the lights to work. Current for lighting flows through one wire to the light, thru the filament and out to ground.
You can test this by measuring voltage between the power wire and the truck bed. If you are grounded you should get ~12 V. Also test between the power wire and the frame. If you get ~12 V here but not against the truck bed, install a ground strap between the truck bed and the frame to establish a ground.
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Brake lights do not work when tail lights are on?
On a toyota tacoma 2003 SR5 when the tail lights are turned on the brake lights come on and when the tail lights are of the brake lights work just fine what could be the problem. If the truck has a trailer plug, inspect the plug and plug wiring for damage and corrosion.
When Headlights come on dash and taillights do not on my 93 chev truck?
Check your fuse for tail lights. I think the dash and tail lights are on the same fuse so you know when your tail lights don't work. Might have a short or an open in that circuit.
Your tail lights wont work when your headlights are on The brake lights dont work at all Fuses are fine Headlight switch is good What is wrong with your tail lights and brake lights?
I suspect either a faulty ground circuit, or a much easier fix, faulty bulb/bulbs. You might be surprised the havoc a grounded out bulb will cause an electrical system.
Why would the rear lights not work if the brake lights do on a 1986 Toyota truck?
Check the tail light bulbs. These bulbs do double duty. Thet are both the tail light & the brake light. Tail light part might be burnt out.
Chevy truck tail lights do not work and the turn signals flash too fast?
bulbs are to small Check the fuses.
What is the problem if all tail lights brake lights and turn signals work on a 1999 Ford pickup and the tail lights on the horse trailer don't work?
I would first check the grounding between the truck and the trailer. If the ground is good then bulbs would be the next thing to check.
Your head lights and tail lights do not work Brake lights work Fuses are ok?
94 mercury grand marque dashboard, hazard, and tail lights do not work?
Why the tail lights on a 1979 ford farmont stationwagon wont work but the break and turn lights do?
Try checking your grounds to make sure your wires are grounded properly. I had this problem on a 1983 Cougar one time. .
Why does your tail lights only work when you press on the brake?
Are you saying your tail lights themselves do not work and only the brake lights work. If that is the case, check the fuse, and then check the tail light bulbs.
What does it mean when the brake lights work on a 2006 Escalade but the tail lights do not work?
The tail lights and the stop lights work off of different circuits. The stop lights work when the brake pedal is depressed while the tail lights work when the light switch is turned on. Look for a burnt fuse or a bad connection.
What is the problem when head lights are on and the tail lights dont work but the brake lights work?
If the headlights are on and brake lights work but not the tail lights, it is possible there is a short in the electrical wires. Another cause for this could be that the tail light bulbs are burned out. Most vehicles have more than one bulb inside the tail lights to control different lights at the same time.
Why would Brake lights for semi-truck work but not on trailer Trailer works with different truck?
Try the tractor with a different trailer, the pig tail is most likely not connecting properly.
