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Ask Ted Ritter Your Own Question
Ted Ritter
Ted Ritter, Toyota Master Tech
Category: Toyota
Satisfied Customers: 4183
Experience:  Toyota Master Tech, ASE Certified
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I have a 2003 Toyota ghlander equipped with towing package.

Customer Question

I have a 2003 Toyota Highlander equipped with towing package. The tail light' license plate lights and front fog lights do not burn. I changed the bulbs in the tail lights and license plate sockets. The tail light bulbs were burnt. I replaced the blown fuse in the interior fuse panel but it blows every time change it.
Submitted: 1 year ago.
Category: Toyota
Expert:  Ted Ritter replied 1 year ago.

hello, thanks for posting

Electrical issues can be a bit difficult to solve here but let me give it a try, there is obviously a short circuit to ground causing the fuse to blow, which I assume is the 'tail'fuse located in the inside fuse box,

First disconnect both wire harnesses to both tail light assemblies, turn the headlights on, does the fuse still blow?

If yes, the short is further to the front, if not the problem is in one of the light assemblies, the problem can also be caused by a faulty towing hitch wiring, so if it has a towing hitch please let me know.

If further diagnosing is needed a volt/ ohm meter would be a great help. let me know how this goes for you.

Customer: replied 1 year ago.
It does have a tow package. I will have to run to Autozone and grab some more 10 amp fuses and electrical contact cleaner. I'll let you know when I have done what you instructed.
Expert:  Ted Ritter replied 1 year ago.

Thanks for the reply

I just realized that you said it had a towing package in your first post, if the fuses still blow try disconnecting the towing harness from the chassis harness and see if it fixes it, if it does you most likely need to replace the towing electrical converter box or possibly have it redone, depends on what system it has aftermarket or factory.

Customer: replied 1 year ago.
Ted
I disconnected the wiring harness from both tail lights; fuse blown. Then I disconnected the factory wiring harness from the connection in the black box underneath the vehicle; fuse blown. What next? Could the license plate lights be the culprit?
Customer: replied 1 year ago.
Also, before I reconnect the previous items, would it be a good idea to spray them with electrical connection cleaner just for good measure?
Expert:  Ted Ritter replied 1 year ago.

Thanks for the update

Yes the license plate lights are on the same circuit so they could be the cause as well. Go ahead and use the connector cleaner. If it's not the license lights go to the front of the car and disable tha parking light/ side marker lights, they are also on the same circuit.

Customer: replied 1 year ago.
To unplug the parking light/ side marker light, I need to unbolt the entire headlight assembly correct? If I'm looking at the correct plug, it is behind the side walk of the engine compartment. To remove this assembly, I will need to loosen the front bumper cover and pull the grill out?
Expert:  Ted Ritter replied 1 year ago.

Ok, let's see if we can avoid doing all of that, I think you can reach in from behind to get to the connector and unplug it if not, let me know. Is the tail fuse the only one that blows? Does it blow as soon as the headlight switch is turned on or before?

Customer: replied 1 year ago.
The fuse blows as soon as I turn the headlights with on. The fuse that keeps blowing is # ***** on the interior panel. I cannot reach the side marker connector from inside the engine compartment.
I recently replaced the OEM hazed and yellowed headlight assembles with non-OEM ones but I am not sure that the tail lights weren't working before I replaced the headlight assemblies.
Expert:  Ted Ritter replied 1 year ago.

I understand, does it have fog lights, they are also on the same fuse, also try to remove the tail light relay under the hood and see if the fuse stays intact.

Customer: replied 1 year ago.
Ok... Some progress
I was able to access the corner light connections via inside the shell well covers. After I removed the connectors, the fuse no longer blows. I guess the fault lies in the new lights. I'm going to go to Autozone to see if I can purchase replacement bulb fittings. The fog lights are operable now as well.
Expert:  Ted Ritter replied 1 year ago.

Great, looks like you have found the problem, the white/black wires are ground the other green wires should not be grounded

Customer: replied 1 year ago.
Ok. I'll have to buy the new fittings tomorrow. I will let you know if all the lights come on when I get it all back together.
Expert:  Ted Ritter replied 1 year ago.

Ok, keep me posted.