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Mike S.
Mike S., ASE Certified Technician
Category: Dodge
Satisfied Customers: 6702
Experience:  ASE certified
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Sittting at a stoplight with left turn signal on and foot on

Customer Question

Sittting at a stoplight with left turn signal on and foot on brake, turn signal switch smoked and lost brake light and turn signals and flashers. Replaced turn signal switch and stop light switch and checked harness for loose connections and made sure grounds were all good. everything worked for two days, then sitting at stop light again with left turn on, and foot on break, and smoked the turn signal switch again.
JA: Have you checked the brake fluid? How's the level and when was it last changed?
Customer: Yes checked it it is full, but never changed it, didn't know you could. 99 Dodge 3500 cummins.
JA: Are you fixing your B3500 yourself? What have you tried so far?
Customer: I have over 40 hrs in it, bat terminals were a little corroded change and cleaned them, thought I was loosing ground there, change stop light switch again, and turn switch, both worked until I turned turn signal on and hit brake, turn switch made smoke again, then nothing.
JA: Anything else you want the mechanic to know before I connect you?
Customer: Check all connections from cab to bed and all grounds are getting connection.
Submitted: 20 days ago.
Category: Dodge
Customer: replied 20 days ago.
Never blown a fuse on either brake lights or turns or flashers, also replaced flasher, yesterday I was trying to figure it out and bypassed brake light switch, had lights if I hit the right terminal on the plug, replaced just brakelight switch, still no brake lights, turned on 4 ways, they did not work, but with 4 ways on I had brake lights. Drove home from jobsite, 70 miles brake lights worked till I sat at a long stop light, then turn signal switch smoked and no more brake lights.
Customer: replied 20 days ago.
Also thought it might be trailer brake switch after market add on, disconnected it. no help. This truck has been on jobsite for months so I would work on it for a while and track wiring for shorts breaks and corrosion, put on new stop switch and turn signal switch, try it again, and then everything works till I hit brakes with turn signal on (Either right or left) then it makes smoke from steering column from turn signal switch hole, and everything quits. Also when it makes smoke engine surges when Idling, if running.
Customer: replied 20 days ago.
Tracked wiring from turn switch, to brake light switch, it splits and goes to what feels like a control box under dash above accelerator pedal, can feel it and barely see it but can't get to it, does this box have anything to do with brakes and turn signals?
Customer: replied 20 days ago.
Fed up, with this dodge ready to part it out, or just scrap it, but it is a good truck other than this issue, only has 125,000 miles on it. bought it new, and it sits on job site for months at time, just moving around a few miles a day.
Expert:  Mike S. replied 20 days ago.

Hi, I am Mike, welcome. I'm reviewing your question.

Expert:  Mike S. replied 20 days ago.

What amp fuses do you have installed for these circuits?

Customer: replied 20 days ago.
20 amp hazard, 20 amp stop light under hood, 10 flasher on side of dash.
Expert:  Mike S. replied 20 days ago.

Ok, my manual lists them by a number but I will assume they are the flasher fuse #4, the stop fuse #5 and the turn #1 and it is in the junction block and is a 15a. The other 2 are 20a. You are ok actually with all 3 of those, even the 10a instead of a 15a for the turn.

Are you saying you never blew a fuse at any time when these switches are smoking?

Can you tell exactly what is burning up in these switches, what color wire?

Expert:  Mike S. replied 20 days ago.

Just in case I need to refer to them, here are the EXTERIOR LIGHTS wiring diagrams. Do you have an ammeter or multi-meter?

Customer: replied 20 days ago.
Never blown a fuse since this problem started. The smoke comes from the turn signal switch in the steering column. there are no wires burnt. I guess you would call the turn signal switch the controller, because it has wipers and bright switch all in one.
Yes I have ammeter and multi-meter. Checked continuity on all wires I could find in Chilton manual wiring diagram but it does not show many of the wires that are actually in the harness.
Expert:  Mike S. replied 20 days ago.

Sorry, forgot the diagram.

it's normally called a multi-function switch.

Do you still have any of the old burnt up switches?

If so, take them apart and take some photos and show them to me of what is actually burnt or melted.

Customer: replied 20 days ago.
Noticed when drove last time the cruise control quit working also, could this be tied to this problem? Or Causing it? The brake switch has to be tied into the cruise control at some point?
Expert:  Mike S. replied 20 days ago.

I think at this point you should probably have all of the codes retrieved from all of the modules and see if any refer to any of these circuits.

Customer: replied 20 days ago.
It is not showing any codes, or it wasn't last time I stopped at dodge dealer and they hooked to it.
That is a better diagram than what I have found. Let me get busy with my multi-meter and check everything for continuity and power going to, and coming out, of the multifunction switch (again). From what I have deduced so far, is that if it is not blowing fuses, it is not a dead short, I first thought it was an open ground and was back feeding power to the multi function switch. But I cleaned and checked all the grounds I could find, with this new diagram, I will go back and double check and see if I missed something.
Expert:  Mike S. replied 20 days ago.

Do you still have any of the old burnt up switches?

Customer: replied 20 days ago.
Just the one that is on it now, but I will remove it and open it up if I can figure out how to. May have to break it to open it but it is worthless anyway.
Expert:  Mike S. replied 20 days ago.

What did you do with the old ones?

Customer: replied 20 days ago.
Autozone warrantied three of them I exchanged them, if I destroy this one I won't be able to exchange it, but if it helps me get it fixed I'll buy a new one.
Customer: replied 20 days ago.
I threw the original factory one that smoked first away.
Expert:  Mike S. replied 20 days ago.

Ok, let me know what you find out.

Expert:  Mike S. replied 20 days ago.

any news?

Expert:  Mike S. replied 19 days ago.

Did that answer your question? If so, kindly leave me a positive rating, so I get credit. After all, you have already made the deposit.

Customer: replied 18 days ago.
I haven't had time to check it all out yet, I got busy with work, (That Comes First), When I get time I plan on checking all wires associated with the brake lights and turn first with continuity, then pull some amperage through them with a load test. I will break open the fried multifunction switch first, what I find in there may narrow my search. I have done this before, but I will do it again just to be sure. The wiring diagram you gave me might speed things up this time.
Surely I haven't just got three bad Multifunction switches in a row?
Expert:  Mike S. replied 18 days ago.


Expert:  Mike S. replied 15 days ago.

Any news?

Customer: replied 14 days ago.
Still working on it, no luck yet.
Expert:  Mike S. replied 14 days ago.


Customer: replied 6 days ago.
Ok, I checked all grounds, cleaned them and checked with continuity tester, did find the plug at stop light switch had been hot, showed signs of melting, so I replaced it. Unplugged multifunction switch and rigged a 12v Positive wire from battery with a ten amp fuse inline. connected to front turns and rear turns individually and they come on and do not blow fuse. No shorted or open connections. replaced break light switch, flasher relay, and multifunction switch.
They should work, but no brake lights, or turn signals. Turned on hazards and hazard relay, and multifunction switch, both smoked. No blown fuses. What now?