Turn signals not working, blowing fuse

-
hotrod swinger

hotrod swinger

Well-Known Member
Joined
Mar 6, 2020
Messages
656
Reaction score
470
Location
Sooke
1973 Dart

headlights work
Brake lights work
Hazards work, including indicator
All bulbs are functional

turn signal switch gives me nothing, no lights, no clicking, no indicator

UPDATE: Fuse blows as soon as the key is turned on.

just looking for guidance as to where I should continue diagnosis
 
Last edited:
When the turn signal is switched to either side with the brakes pressed what does the brake lights do.
 
hotrod swinger said:
the brake light turns off on that side
Click to expand...
That's a good sign.

Have you replaced the TURN signal blinker mechanism?

There are 2 blinker mechs on for flashers and one for turn signals.

I 67s the turn signal blinker is to the right of the ash tray
Someone recently mentioned in the 70s it is closer to the fuse block. Do t know for sure.

Any chance you put in LED bulbs?
 
For a single bulb tail light that is correct.
Since the inside indicator isnt lighting up. I'd look see if there is voltage at the flasher unit.
 
Looked a little more closely and I have a blown fuse at #2. What the hell, I went for a drive today and it was working just fine and quit on me in the middle of my drive.

Replaced the fuse, turn signal is off and it blows when I turn the key on.
 
Dana67Dart said:
Is 73 separate bulb for turn signal?

I feel like the "unbecoming your parent" progressive ad people
Click to expand...
Wasn't sure, so I just wanted to be clear about it.
Looking at a '73 FSM now. Looks like the same setup on our '67s excpet of course the sidemarkers.
And the sidemarkers for the Dart/scamp are wired with a seperate feed unlike the Valiants. Go figure.
 
Last edited:
This is a colorized version of the turn signal operation.
The orange represents the switch contacts signalling left.
The contacts connect the power from the flasher unit to the wires on the left side.
upload_2022-1-9_15-53-18.png


When the brakes are applied at the same time, power goes through the stop switch, through the hazard switch to the cener contact of the turn switch and right side rear wire.

Turn signal flasher unit gets power from the keyed accessory circuit. No fuse. The flasher itself is essentially a circuit breaker.
Brake lights get power from the main splice. Key off doesn't matter. If that fuse is good, they get power.

I think you're familiar with this but if not
upload_2022-1-1_13-31-34-png-png.png
 
Last edited:
Thanks very much for setting that out. Now, where are the most likely areas for a short causing my fuse to blow?
 
hotrod swinger said:
Thanks very much for setting that out. Now, where are the most likely areas for a short causing my fuse to blow?
Click to expand...
I thought it was the turn signals not working. [There's no fuse on them.]X see next post
What fuse opened? Never mind. You said 2.
Hold on.
 
Last edited:
Mattax said:
There's no fuse on them.
Click to expand...
oops-gif.gif
Looks like I'm wrong about that. Earlier cars didn't have a fuse on them but the FSM says your '73 does.
upload_2022-1-9_16-20-10.png


If I'm reading right, that fuse is shared with the heater.

Since its failing as soon as you turn on the key, first check that both the heater fan and the turn signals are off.

If the fuse opens with both switches off, then probably one of the wires between that fuse and either switches is contacting ground.

EDIT
Looking at the wiring diagram, Fuse 2 should simply be A/C.
The fuse list from the shop manual then gets read like this.
upload_2022-1-9_16-40-50.png


So Turn and Stop are on the same fuse, number 3; along with the reverse and heater fan.
 
Last edited:
FYI, the heater was off this entire time.

I tried disconnecting the turn signal switch, and fuse blew again as soon as I turned the key on.
 
hotrod swinger said:
FYI, the heater was off this entire time.

I tried disconnecting the turn signal switch, and fuse blew again as soon as I turned the key on.
Click to expand...
I updated my post. The only thing the FSM shows for that fuse is A/C.

What happens when the car is started without that fuse?
 
OK. So it is the stop light and turn signal fuse.
hotrod swinger said:
The car starts fine without that fuse.
Click to expand...
I was trying to narrow down what didn't work when Fuse 2 opened.
Now knowing its fuse 3, the program (factory info) still makes sense.
And just as a heads up, the wiring diagram shows the stop light switch on fuse 4, which makes sense. Fuse 4 is always hot, key on or off.

We know:
Fuse 3 opens with Turn signal off, radio off, heater off.
Therefore it has to be shorting between the fuse and those switches. Right?

I'd be tempted to go to the flasher unit first. See what it looks like and if nothing obvious, disconnect it and see if then probe for a ground on each side of the flasher connector.

Do have the shop diagram?
I know its a pain to read but its helpful in showing what connects to what.
 
Thanks Mattax, I have the FSM and diagram and yes it can be a pain in the *** to follow lol.

Took your advice and swapped in a spare turn signal flasher. Everything is working again, yay!

I tried swapping the turn signal flasher earlier in the diagnosis but it didn’t work because the fuse had burned out, duh.

Thank you very much for the assistance.
 
hotrod swinger said:
Thanks Mattax, I have the FSM and diagram and yes it can be a pain in the *** to follow lol.

Took your advice and swapped in a spare turn signal flasher. Everything is working again, yay!

I tried swapping the turn signal flasher earlier in the diagnosis but it didn’t work because the fuse had burned out, duh.

Thank you very much for the assistance.
Click to expand...
Great! Maybe internally the flasher grounded to the housing.

ya. Its helpful though when getting into the nitty gritty.
Following black wire D1 from the flasher, it goes to the bulkhead C2, position 8. From that junction it changes to white wire B1:BangHead: . Whodda guessed that.
B1 to the radio connector where it joins with X1, red* 14 ga wire. Follow that back to the heater switch where it joins with C1, Black* 14 gage that comes from fuse 3.

I've not spent a lot of time with the later wiring and between the color changes and the location at the end of the line makes figuring out the relationships harder. The diagram is a big help even though its a pain.
 
Last edited:
hotrod swinger said:
I didn’t know a bad flasher could blow a fuse
Click to expand...
Hey I didn't know the flashers were on a fuse. I have owned '74 and '75 A-bodies. Maybe I knew and forgot. LOL.
Maybe heavier wire to the flasher was used in the early cars. I'd have to look at the diagram. But doesnt really matter as you solved it.
 
Regretfully I am back to square one. Blowing fuses. Worked for a few minutes, now it’s the same issue.

this is really discouraging. Am I going to have to take my dash apart.

this is really bumming me out.
 
hotrod swinger said:
Regretfully I am back to square one. Blowing fuses. Worked for a few minutes, now it’s the same issue.

this is really discouraging. Am I going to have to take my dash apart.

this is really bumming me out.
Click to expand...
Maybe some wires moved around with the flasher out.
I think you can narrow where to look.
Use the ohmmeter or continutiy check on the flasher unit that was removed.
The two terminals should have continuity. The feed terminal should not have continuity to the shell. If it does, then that was a problem.

Next, remove the fuse and see if there is continuity between the fuse terminal and ground. If so, then at least you know for sure its a short to ground your hunting.
So knowing that, now go ahead and disturb the flasher wires. Remove the new flasher unit and take a probe to the flasher connector feed terminal. Take the other probe to ground. If there's continuity, then that wire is grounding.
If not, then check th eother side of the connector. That side is going to the turn switch and we know column connectors and wires can get damaged.
 
You moved the flasher. Bare wire. Cant be that hard to find.
 
by any chance are the bulbs all correct and correctly installed?
I have seen this happen in several ways;
a bulb inserted wrong
A wrong bulb installed.
An already internally shorted bulb installed.
If it was me, I'd start by removing all the bulbs, and see if the fuse still blows.
What's odd to me tho, is that if a short to ground exists anywhere after the flasher, it usually makes the flasher , flash much faster than usual.

I have seen quite a few aftermarket signal switches, melt, and then the contacts recede into the plastic. This usually only affects the rear stop and tails; but who knows.........
 
You must log in or register to reply here.
-

Back
Top