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9/02/2018 10:26 PM  #1


Turn signal is still kicking my butt. Need a sanity check.

A little while ago I troubleshot my turn signal issue down to the switch in the steering column. I ordered a couple to make sure I got at least one good one. 
Installed the first one. Right front blinker was still not functioning. Troubleshot the into the switch again as the white/blue wire has no continuity through the switch. 
Put the second one in, left the switch exposed and tried it out. Smoke appeared to come out of the switch. Not good. Turned everything off. This is where it gets weird. Right rear blinker works fine, Left blinkers work fine, just not the front right blinker. Hint White/blue wire. I put ohmmeter on the blue wire and find it grounded out at the switch. The wire for the left front wire is open. I pulled the wiring to the right front turn lamp and it was an open. 

Sanity check I am looking for is the flasher module and the turn signal indicator on dash. What impact are these having on the continuity checks? I highlighted the power to the switch path in red, and the power to the front right bulb in yellow. I added the green arrows where I think I should take ohm measurements. Problem is the couple of blue circled areas where I don't know what the blinker flasher and the blight dash light will have on my measurements. 

When I measured for 12 vdc at the front right blinker socket I got nothing. I measure 12vdc coming into the turn signal switch and going out through the three other paths just fine. I have original type wiring and no cuts and hacks into the circuitry. 

​Any ideas??

 

 

9/02/2018 10:58 PM  #2


Re: Turn signal is still kicking my butt. Need a sanity check.

The turn signal flasher on my '66 is connected to the driver side vent under the dash.  It is difficult to find, but is at about 10 o'clock on the vent pipe.

I've never had a problem with any wiring harness, except for failure of the wire between the starter relay and the voltage regulator. So, I replaced both harnesses with stock replicas from Mustangs Plus.  No problems.

A couple of times the nylon prongs on thee turn indicators have broken.  Got new ones with no wires attached and re soldered them to the original wires.  Still working after more then 20 years.


Original owner - 351w,T-5, 4whl disks, power R&P
 

9/03/2018 5:07 AM  #3


Re: Turn signal is still kicking my butt. Need a sanity check.

hello , i am far away to be an electric guy but i will go to basic and check the silly things may happens like: 
Light socket  broken , bulb holder , broken wires , broken bulb , no ground , flasher relays too old ?
the smoke is not a good sign.... shortcuts in action 

Have you changed some bulbs around the car ?  
the fuse are good  ? 
hope it helps

 

9/03/2018 6:14 AM  #4


Re: Turn signal is still kicking my butt. Need a sanity check.

You should get continuity from the turn signal switch to the right front bulb; the dash lamp and flasher would not impact this reading.  The dash bulb only increases the resistance, so a check from either of the two green arrows at the switch to the bulb should be close to zero ohms.  Your check points at the green arrows are correct.
Note, for the dash lamp to function, it needs +12v on one leg, and ground on the other leg.  From the circuit diagram, it appears that the blue-white wire needs to be +12v and the green-white needs to be ground for right turns, and visa-versa for left hand turns.


65 Fastback, 351W, 5-speed, 4 wheel discs, 9" rear,  R&C Front End.
 

9/03/2018 7:23 AM  #5


Re: Turn signal is still kicking my butt. Need a sanity check.

Thanks BobE. This is a 1965 FB with pre-April wiring and Dashboard. Meaning there is a single bulb flash indicator which shows both left or right. I put LED lights in the dash and I remember that light bulb had two clustered LEDs inside with a grounding wire to complete the circuit. LEDs read differently when using an ohmmeter. I can't remember but it should read as an open. Regardless the path to the front left should read the same. I had to break away and get some sleep to get some fresh perspective on it. Think I will measuring where is goes through the firewall junction and see which side my issue is on. 

     Thread Starter
 

9/03/2018 9:03 AM  #6


Re: Turn signal is still kicking my butt. Need a sanity check.

HAD THIS ISSUE,   my cars fuze box is powered 1st thru the cig lighter fuze then flashers, weird but check all fuzes for 12 volts output ,  just a fyi   

Last edited by Don (9/03/2018 9:06 AM)

 

9/03/2018 9:19 AM  #7


Re: Turn signal is still kicking my butt. Need a sanity check.

Hey Ed, The old saying is that all electrical components are made with built in smoke, let the smoke out and it’s time to replace it!! 

Let’s see if I’m understanding you right. Left side blinkers good.Right rear blinker is good. Right front does not work. Does the right front running light function?  

“I put ohmmeter on the blue wire and find it grounded out at the switch.”
Should have this been white / blue?


I think of the flasher as a relay contact, the load from the lights causes it to open momentarily then close again. I shouldn’t give you any issues with trouble shooting if power is passing through.

If you pull the bulb from the dash turn indicator, I would think you are clear for continued trouble shooting.

The lights are grounded through the sockets. So, with a good lamp in the right front socket, you should read Ohm’s to ground from the 38C connector out to the socket cause you are reading through the lamp filament. The Ohm’s between the right side and left side should be close to the same. Neither side should read as a direct short. With good readings, I would try sending the signal from the left blinker (38A) to the right side. If it operates correctly, the wiring on the car is good and the switch needs to be re-evaluated.   

If the wiring has a reading to ground on the yellow highlighted section between the switch and the 38C connector, something is wrong with the switch, and probable the reason for the smoke!!

Last edited by Bolted to Floor (9/03/2018 9:21 AM)


John  -- 67 Mustang Coupe 390 5 speed
 

9/03/2018 12:29 PM  #8


Re: Turn signal is still kicking my butt. Need a sanity check.

leds lights sometimes give resistence issue ,  but normally when you change to leds , bulbs without add a resistence. 
I dont think idiot light give you so much trouble but .....

 

9/03/2018 12:39 PM  #9


Re: Turn signal is still kicking my butt. Need a sanity check.

Bolted you are right I meant to say White/Blue wire. Was tired last night, I did highlight the correct wire on the diagram I was chasing.
Well I found the problem. Kept chasing the issue to the front right corner. Had to tear the wiring out of the lamp assembly to directly find the problem. Less than 8k miles on these cheap -oh no I used a word I shouldn't have- Chinese made POS Scott Drake things.

     Thread Starter
 

9/03/2018 1:28 PM  #10


Re: Turn signal is still kicking my butt. Need a sanity check.

Glad you found the issue.


John  -- 67 Mustang Coupe 390 5 speed
 

9/03/2018 4:13 PM  #11


Re: Turn signal is still kicking my butt. Need a sanity check.

The good thing about difficult problems is that they leave a lasting impression/ memory and become easier the next time.


Mustang Steve Bash in Gruene, Texas September29-30, 2023
 

9/03/2018 8:59 PM  #12


Re: Turn signal is still kicking my butt. Need a sanity check.

Al I hear what your saying, but when every bit of wiring in this car is only a few years old with less than 8k miles on it, I don't expect to find anything to this level of wrong. Just cheap crappy manufacturing is all to blame on this. 

     Thread Starter
 

9/05/2018 10:32 AM  #13


Re: Turn signal is still kicking my butt. Need a sanity check.

Great troubleshooting example. Keep up the good work, guys.


Money you enjoy wasting is NOT wasted money... unless your wife finds out.
 

Board footera


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