Turn signal switch

[Mike Szadaj]

Huge problems. Yesterday the turn signal switch started smoking. Today I bought a brand new one, more smoke and now nothing. I also have no brake lights. Does anybody have a schematic of the switch? The FSM just shows the wires going in and out of a circle.

 

[PurpleBeeper]

Damn....it sounds like whatever shorted the first time is still shorted. The switch itself is obvious if it's out & you're looking at it. I think the main thing to check first is that the wires on either side of turn signal switch plug are in the right locations. Then start working backwards up that wiring harness looking for melted wires & comparing vs. the wiring diagram. Maybe take a meter & check for crossed wires, power where it shouldn't be, ground where it shouldn't be, etc. Once you find the crossed/shorted wires it probably won't be too tough to fix.

 

[Mike Szadaj]

That's why I thought a schematic diagram of the switch itself would help. After I started this thread I broke the insulation off of the back of the first very smoked switch (with the second I was on the lookout and shut the key off before major damage). It looks as if the brown wire is the one that got hot. That one goes through the flasher to the ACC connection of the ignition switch. So that can be considered the source or start of the circuit. But I would like to know what wire it connects to through the turn signal switch. That would be the rest of the circuit. Maybe I should just rip/cut the burnt switch apart. I should be able to see what connects to what then.

 

[Mike Szadaj]

Big discovery today. The brown and black wires going to the passenger stop light are shorted together. Now I need to find out where. I am going to disconnect the rear light wiring harness at the driver's kick panel. I will then recheck for the short. If still shorted , the short is in that harness. If no short, it is in the dash harness. Car is at muffler shop overnight, can't do anything till I get it back tomorrow.

 

[Mike Szadaj]

Before I discovered the short, I was totally flabbergasted when one filament of the bulb was lit with the bulb socket completely out of the taillight sitting on a blanket! The rule is it must be grounded, right? I haven't figured it all out completely, but here is what was happening. If you apply 12 volts to the two small round contacts on the bottom of the bulb, one filament will light. One leg of each filament is tied together, then attached to the base of the bulb. So if you run 12 volts through both of the bottom contacts, the electricity runs through one filament, to that tie point, and then through the other filament. Because the filaments are different sizes, they have different resistance. The filament with the higher resistance lights, and the other basically acts as a resistor. So, what I think happened was somehow one of the wires acted to supply 12 volts, and the other acted as a ground. Has anyone ever seen this phenomenon?

 

[wozniakjm]

Before I discovered the short, I was totally flabbergasted when one filament of the bulb was lit with the bulb socket completely out of the taillight sitting on a blanket! The rule is it must be grounded, right? I haven't figured it all out completely, but here is what was happening. If you apply 12 volts to the two small round contacts on the bottom of the bulb, one filament will light. One leg of each filament is tied together, then attached to the base of the bulb. So if you run 12 volts through both of the bottom contacts, the electricity runs through one filament, to that tie point, and then through the other filament. Because the filaments are different sizes, they have different resistance. The filament with the higher resistance lights, and the other basically acts as a resistor. So, what I think happened was somehow one of the wires acted to supply 12 volts, and the other acted as a ground. Has anyone ever seen this phenomenon?

Im having a very similar issue with my 68 Charger. What did the fix end up being?

 

[mountain33]

Huge problems. Yesterday the turn signal switch started smoking. Today I bought a brand new one, more smoke and now nothing. I also have no brake lights. Does anybody have a schematic of the switch? The FSM just shows the wires going in and out of a circle.

I have a hand drawn diagram of switch on an earlier post titled Brake light not working. Not sure if it will help. 71 RR switch

 

[wozniakjm]

Awesome thanks! I'll check that one out as well. So far I have replaced the TS switch and have successfully fried a new one. I have another on the way but dont plan to continue that cycle. Both times, smoke came from the horn area. Now, front drivers side TS works and passenger rear TS works. All parking lights work which is leading me to it being a grounding issue somewhere. Thanks again for the sketch and any additional info you can think of.

 

[Mike Szadaj]

Im having a very similar issue with my 68 Charger. What did the fix end up being?

Finding the short, which was in middle of the wiring running from the driver side lights over to the passenger side lights, and fixing that short.

 

[wozniakjm]

Finding the short, which was in middle of the wiring running from the driver side lights over to the passenger side lights, and fixing that short.

Got it, thanks. I think mine is fixed after a day of doing end to end checks on all of the wiring harnesses related to the problem. Found a couple wires that might've been the culprit at the drivers side taillights. Time will tell but so far so good.

 

[Mike Szadaj]

The smoke from the ts almost surely is a short to ground. If you unplug the connector under the kick panel, take out all bulbs and do continuity check between each of the wires going to the stop/turn bulbs and ground (tthe frame) you should not show any continuity. If you do, that wire is shorted to ground.

 

[Mike Szadaj]

The wires going from that connector to the rear of the car that you need to check are the dark green and the brown.