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Discussion Starter #1
Hallo,

I own a rav4 from 2003.
I frequently use a trailer with my RAV 4 and recently I have problems with one of the light circuits. The left rear light from the trailer doesn't work. Also the left and right front light and the left number plate ligt are connected to this same circuit. None of these lights are working. These lights are connected to pin 58L (12V) and pin 3 (mass) from the trailer socket.
With all 4 lights disconnected, i measure 12 Volts DC on the wires, or at the connector (58L and 3). When I connect one of the bulbs...and it doesn't matter which one..the voltage goes to 0!
I tried to connect a bulb directly to the female trailer connector from the car by using 2 wires and connect the bulb to pin 58L and 3. This gives me the same result. So without a bulb I have 12V and when i connect a bulb to the circuit, this pulls the 12V to 0. With these facts I can conclude that the problem should be somewhere in the car wiring and not in the trailer.
But what is pulling down the 12V??
Any suggestions?

Thanks in advance.

Sven
 

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The problem is most likely in the ground circuit otherwise depending on how you're measuring the 12V going to 0 you'd be blowing a fuse.
 

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Discussion Starter #3
Thanks for your reply.

I've found the problem, it was an oxidized contact in the cable harness in the car. This had a very high resistance. Without connecting a bulb, i measured 12V..but with a bulb...all the voltage went to the high resistance.

regards, Sven
 

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Yep, an oxidized contact will do it. And thanks for letting us know the outcome. Many times we never hear and that discourages our trying to help.
For testing 12V circuits I like my old probe with it's filament bulb since it puts a load on the circuit to see if power is "really" there.
 
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