Topic: 1970 hood scoop turn signal lights

[Hipo giddyup]

  I'm having a heck of a time with the hood scoop mounted turn signal lights. We bought a repro turn signal light harness for the hood scoop, but every so often one will not light. I ended up rechecking the voltage, bulbs, etc and finding out its likely a loose bulb in the socket. I understand its repro but any time you shut the hood its a gamble whether one or both will work. I just did this again yesterday, pulling the bulb then reseating it, and when I put the right turn signal on, the light started blinking fast and then stopped (only in a few seconds time). I unhooked the hood scoop socket on the right and it was warm? It had blown a fuse. I replaced the fuse but now when you turn the key on it blinks fast, doesn't make a flasher sound, and will not stop ie. moving the turn signal stalk back to the middle or even left turn signal position changes nothing. The only way to stop this is to unhooking the turn signal switch harness or unplug the flasher. Of course I have no turn signals now!! Any ideas what could have happened? Or where to start in finding the fix? The flasher is new and turn signal switch is a brand new Scott Drake, and we only have a few thousand miles on the restoration of the car.

Other features still work on the turn signal switch such as the horn, and wipers, radio thats on the fuse,etc.   :'(

[midlife]

I would first unplug the hood scoop turn signals and see if everything turns back to normal.  If it does, the problem lies in that system.Doublecheck that the ground is good (remember you sometimes need to sand the paint down to get good contacts). 
Sounds like you have a possible short in that socket on the RHS...

[Hipo giddyup]

Adding more, I left it unplugged, full harness connection from the harness plug at the firewall. Same thing, right blinker keeps blinking with the key on, moving the stalk does nothing to change it. I'm worried something  got fried in the turn signal switch or the flasher is fired?/ If I unplug either it of course stops. Strangest thing I have ever ran across.

[midlife]

Start by removing any RH turn signal bulb on the outside of the car.  If it doesn't change things, put it back and start on another bulb.  If that still doesn't change things, remove all bulbs and add them one by one until you find the culprit.

[mtinkham]

I had a problem with a 70 convertible that I had. Signals would blink fast, some didn't work, the rear lights didn't blink at the same time as the side lights or dash indicators (If I am remembering correctly).

The front signal light assemblies were not adequately grounded...the paint I used to replicate the plating was quite the insulator!

[jwc66k]

At this point:
- Remove the harness and bench test it, with and without bulbs. The wiring diagram is in the "1970 Mustang Electrical Assembly Manual" (AM 0033), pg 86, installation is on pg 23. Pay close attention to the sockets. That means use an ohmmeter. The harness should work electrically when plugged in and while sitting on the fender, with a towel between the harness and the fender (scratches).
- Buy another harness and bench test it before you install it.
- Check the flasher. Some are rated for only two lights. You got three.
Jim

[Hipo giddyup]

Thanks for the replies. I will look into the flasher (I had the emergency flasher), maybe it got messed up? I also replaced the rear tail light as it was not blinking while the others were. But, I ran out of time last night to test it, etc. I will check the connections to the dash cluster and the ground off the main harness, doesn't hurt.

I am wondering, since there is power coming into the turn signal switch, yellow wire, I assume you can direct that power to different leads on the harness to equate to the left or right turn signal working? Maybe that would rule out if the switch is bad by bypassing it?
 
I will report back with findings, hopefully this will help others!

[Hipo giddyup]

I only had a short time to look at the car today. I replaced the bulb , rear right taillight, but no difference. I will say that when I put the flashers on, the rear tailights flash but not the front. Still , when I have the key on, the right flashers blink fast, no flasher sound, and the stalk doesn't affect anything if you switch left, neutral, right. If I can test the switch in the car, that could be the culprit? as everything goes through the switch.

[jwc66k]

I only had a short time to look at the car today. I replaced the bulb , rear right taillight, but no difference. I will say that when I put the flashers on, the rear tailights flash but not the front. Still , when I have the key on, the right flashers blink fast, no flasher sound, and the stalk doesn't affect anything if you switch left, neutral, right. If I can test the switch in the car, that could be the culprit? as everything goes through the switch.

At this point:
- Remove the harness and bench test it, with and without bulbs. The wiring diagram is in the "1970 Mustang Electrical Assembly Manual" (AM 0033), pg 86, installation is on pg 23. Pay close attention to the sockets. That means use an ohmmeter. The harness should work electrically when plugged in and while sitting on the fender, with a towel between the harness and the fender (scratches).

Please do it right. I am a former US Navy Electronics Technician with a EE. Test as I said.
JIm

[Hipo giddyup]

Are you referring to the hood scoop wiring harness Jim? It is not even hooked up yet I'm still having these issues. If you are referring to the turn signal switch , I'd like to see about testing it in the column. The bottom of the harness is totally exposed and all the column is doing is holding up the harness. Lol
 Now if you are referring to the main dash harness, I'm honestly trying to be less invasive. Midlife went through all of the original harnesses just a few years ago, so if I remove the original , I would likely put back a new one if I go to all that trouble.  If the original harness failed I would probably not invest anymore in repairing it again.
  I will start with checking grounds at the front turn signals, the removing each bulb as said by others. I would like to figure out how to test the turn signal harness while in the column but if it is not going to work, then I'll remove it to test.
I appreciate all the feedback on this issue. Just super frustrating.

[Hipo giddyup]

  Ok, some info back since I had a few hours to fool with the car. I followed midlife's suggestion and removed the right side bulbs, rear, two markers and front parking light. I put one bulb back and tested, same result, it has a quick flash, and NO sound from the turn signal.. very odd. I also cleaned the ground connection at the RH front turn signal to the bumper just for added measure, no change.

 I noticed that the "Belt" light when the key is switched on, and under dash courtesy lights are lit as normal but they have a slight flash to them also. yikes. Again, as soon as the key is on, or in ACC position the right hand lights flash quick.


Now, I google searched for a wiring diagram for the turn signals and ran across this previous post where you guys helped another here with their turn signals not working.

https://www.concoursmustang.com/forum/index.php?topic=15633.15


 I actually followed a lot of this testing and tested the ts harness whilst still in the column, unplugged.

I got this..

With t/s lever down I used ts blue wire (flasher #10) to grn/white (LH front #3) and got 0 with my meter on ohms 200. Then blue (flasher #10) to grn/org (LH rear #8) and 0 again.

With t/s up from the blue (flasher #10) to white/blue (RH front #2) I got 4.8. Then blue (flasher #10) to orange/blue (RH rear #9) 4.8.

This is with the t/s switch not attached to the steering column.

I also checked the RH wires front and rear in this harness when the TS lever was down (left side), and the RH front had 4.8? I checked in neutral position and ts up position and it always has 4.8 ohms? Seems like the switch is grounded or fried??? 

[Hipo giddyup]

Just wanted to give a follow up to where I am with this issue. I purchased a new TS switch and replaced it, doing an ohms test (checked out ok) on the new switch  before hooking into the main harness. All looked good and after connecting, I have turn signals back again!!  However, the turn signal flashing was much faster than normal, but this was at least working on both sides, all lights - in the dash and external. Emergency flashers working perfect. So, I decided to replace the TS flasher, maybe it get a jolt from when the hood scoop harness failed? I replaced it with a new one and now everything is back to normal.

I will be contacting NPD about the failed hood scoop harness, hoping to get a replacement. For now, no hood scoop harness.

Lastly, when I checked the old TS switch, it seems like the lower portion of the actuator, white lower portion where the TS stalk moves the upper switching between left and right, does look a "dark" yellow on the ends. Kinda like it is discolored from heat? but not sure, can't imagine that much heat would've been created is just about 5 secs, but I will say that the right turn signal socket in the hood scoop was warm when I pulled it like it was grounded out?

Thanks for everyone's input with this. And hopefully this could help others with such a weird issue.

[midlife]

Maybe I missed it, but why do you think the repro turn signal harness has failed?

[Hipo giddyup]

Hey Midlife,  from my prior post.


 I actually followed a lot of this testing and tested the ts harness whilst still in the column, unplugged.

I got this..

With t/s lever down I used ts blue wire (flasher #10) to grn/white (LH front #3) and got 0 with my meter on ohms 200. Then blue (flasher #10) to grn/org (LH rear #8) and 0 again.

With t/s up from the blue (flasher #10) to white/blue (RH front #2) I got 4.8. Then blue (flasher #10) to orange/blue (RH rear #9) 4.8.

This is with the t/s switch not attached to the steering column.

I also checked the RH wires front and rear in this harness when the TS lever was down (left side), and the RH front had 4.8? I checked in neutral position and ts up position and it always has 4.8 ohms? Seems like the switch is grounded or fried???


I performed the same test with the new switch and was getting 0 (using 200 ohms setting) for all selections. (hope I understood and did this correct. )  I installed the new switch and now back to normal. I did nothing else but to remove/install the harness. Screws retaining the harness were not loose, didn't see any loose rivets or wirng in the old. thoughts?

[midlife]

I'm sorry, but I was asking about the Hood Scoop Harness being bad and the reasons for it.  You said:
I will be contacting NPD about the failed hood scoop harness, hoping to get a replacement. For now, no hood scoop harness.
I understand that the turn signal was bad.  Did you mean that NPD gave you bad turn signal switch or a bad hood scoop harness?