melting headlight connectors

[diymirage]

hey guys
im working on the family car, 2013 CX-9 with the regular halogen headlights H-11 bulbs

my passenger side bulb had burned out (i thought) and when i went to replace it i noticed the socket had melted a little on the contacts
no biggy, ran out to vatozone and bought a new one
cut the wires, soldered it on and heatshrunk the connections, all is well


about a month later, the headlight went out again and the new socket has the same melted appearance as the one i replaced

what could be causing this?

 

[Frank Mopar]

Bad ground

 

[j par]

A loose Factory Connection that caused shorting and that cause Heat and that burnt your connection. I bet if you renew it like the other one it will probably not do that again.

 

[jos51700]

Drill a hole in the fender and make a miniature little duct to route air to it.

 

[diymirage]

thanks for the replies guys

ill see if i can track down the ground, and clean it all off

@j par it is the one i replaced that melted out again, thats why instead of just replacing it *again* i figured id pick you guys brains for a cause

@jos51700 the way they set this up, there is a big cap on the back of the light and all the wiring is hidden inside of it
not sure if i want to mess with that (got to figure they put some thought into that)

 

[Slowswinger]

Take an ohm reading from the two positive sockets to the + battery and a reading from the ground plug to the - battery. Rhreeeesiztance causes heat.

 

[j par]

thanks for the replies guys

ill see if i can track down the ground, and clean it all off

@j par it is the one i replaced that melted out again, thats why instead of just replacing it *again* i figured id pick you guys brains for a cause

@jos51700 the way they set this up, there is a big cap on the back of the light and all the wiring is hidden inside of it
not sure if i want to mess with that (got to figure they put some thought into that)

Oh crap! I thought you said you fixed one and then the other one did it, my bad.

 

[diymirage]

Take an ohm reading from the two positive sockets to the + battery and a reading from the ground plug to the - battery. Rhreeeesiztance causes heat.

i tried that, and i guess my multi meter is fried
i got nothing on the plug (checked for voltage first) and when i touched it to the battery posts the wires (to the multimeter) started smoking like hilary in church

i got a different meter that tell me voltage or continuity, and that showed all is well, but does not tell me resistance

also, the H11 bulb is a single filament bulb, which only has one positive wire and one negative wire

 

[Slowswinger]

i tried that, and i guess my multi meter is fried
i got nothing on the plug (checked for voltage first) and when i touched it to the battery posts the wires (to the multimeter) started smoking like hilary in church

i got a different meter that tell me voltage or continuity, and that showed all is well, but does not tell me resistance

also, the H11 bulb is a single filament bulb, which only has one positive wire and one negative wire

Your getting the same voltage at the bulb plug as you have at the battery?

 

[Slowswinger]

Try disconnecting the battery, turn on headlight switch, and re check at the battery cables.

 

[Bobzilla]

This circuit carries a lot of amps. Resistance testing and open circuit voltage testing in this case are useless. You will need to get it working again and perform a loaded voltage drop test.
Everything plugged in and lights on, place ground lead of meter on battery negative post, then backprobe ground terminal to the light socket with red lead of meter, while the bulb is lit. Looking for very low reading, typical .1 or .2 volts or less.
Next, backprobe positive terminal of bulb while lit. Should read withing .1 or .2 volts of your battery's measured voltage.
If all ok, circuits are completely fine, and problem was loose connection in the socket, which is common these days.
Also, parts store connectors suck. Get a replacement from the dealer or find one in a salvage yard.

 

[Bobzilla]

j par is basically correct, but you need a good replacement part. The resistance that caused the heat was in the socket itself, in the form a loose connection.

 

[Tooljunkie]

#1 question, when you replaced socket, did it get a new bulb too?

The aftermarket sockets are crimped wire terminals. A proper solder job would solve it.
Terminal grease on connections will also help.