Front blinkers not working

[TexasEd 211]

I've put my car back together. The hood scoop and front valance blinkers do not work.  They have a good ground but not getting any voltage to the harness when the blinkers are on.  

I had the engine bay harness out and re-installed (Disconnected at the firewall).  My dash blinkers work and the rear blinkers work. Ignition, engine temp, marker lights, headlights, etc all work.

Thoughts are that somehow two pins in the square firewall block could have a problem, the think that bothers me is why just those two? 

Any other troubleshooting tips?  @Midlife do you have thoughts?

Secondary problem is that my driver side valance blinker is a 69 with 3 wires and the passenger side is a replacement 70 with 2 wires.  I'll probably need to replace it.  I don't think it will work correctly even if the voltage was getting the the three wire plug.

[Midlife 840]

1970 is incompatible with 1969 front valence blinkers. 

The biggest possibility is that your turn signal is not putting out signals to the front, but the dash blinkers are on the same signal line.  Disconnect the hood scoop harness and try again...

[RPM 1,269]

We are so blessed to have Randy and the udder electrical engineers here. Thanks to all y'all.

[TexasEd 211]

2 hours ago, Midlife said:

1970 is incompatible with 1969 front valence blinkers. 

The biggest possibility is that your turn signal is not putting out signals to the front, but the dash blinkers are on the same signal line.  Disconnect the hood scoop harness and try again...

Thanks, Randy.  I did that a few times.  I tested the harness with volt meter and the hazards on and no voltage at the hood blinkers or valance blinkers. 

I had a front end accident in about 1990 and I think the lower blinkers was replaced.  Both are in sad shape so maybe I’ll get repros.

I’m somewhat resigned to needing to disconnect the block at the firewall and check all the pins but not excited about it.

How long is the turn around for a harness rebuild?

[Midlife 840]

My usual turn-around time is less than it takes for packages to transit to me.

With front end damage in the past, I'd focus upon checking the continuity of pins from the firewall block to the valence and hood scoop pins.

[kblagron 30]

I had an issue on my rear blinkers, and it ended up being that the receptacle that the bulb goes in was 180 degrees out.  I just had to spin the contacts in the receptacle around, and they started working.  Might be worth checking!

[TexasEd 211]

On 1/4/2025 at 8:53 AM, Midlife said:

My usual turn-around time is less than it takes for packages to transit to me.

With front end damage in the past, I'd focus upon checking the continuity of pins from the firewall block to the valence and hood scoop pins.

What do you mean by this?  Take the plug off and to a test from the block to the end connector?  Or is this something about testing from the wiring at the blinker controller to the end without unplugging.  Sorry if it’s supposed to be obvious.

[Midlife 840]

Disconnect the green plug from the firewall/fusebox.  Then do a continuity check for the row with the large pin and 4 smaller pins in a row.

[Mach1 Driver 612]

Guys, it would be easier to discuss on VMF where Ed already has a post going:

https://www.vintage-mustang.com/threads/69-front-blinkers-not-working.1228947/?post_id=11028934#post-11028934

The meaning may become obvious with pictures. That's why I didn't bother posting here.

[TexasEd 211]

OK, that's what I thought you meant.  Before I disconnect the square connector from the fuse box I'm going to try continuity from the flasher module to the plugs at the front of the car.  I can use the tail lights to see if I'm correct.  But at this point I'm already 90% sure I have a problem in that firewall plug to fuse box.  Need to just bite the bullet just reluctant because everything else works and so many pins go through it.

[Mach1 Driver 612]

2 hours ago, TexasEd said:

OK, that's what I thought you meant.  Before I disconnect the square connector from the fuse box I'm going to try continuity from the flasher module to the plugs at the front of the car.  I can use the tail lights to see if I'm correct.  But at this point I'm already 90% sure I have a problem in that firewall plug to fuse box.  Need to just bite the bullet just reluctant because everything else works and so many pins go through it.

Yeah, and its in such a convenient location (NOT). Yes that should work; disconnect the battery, turn signal on, unplug the front light and connect to the correct wire and the output side of the flasher with your ohmmeter, and you should get continuity if all is well. 

[TexasEd 211]

So I pulled the firewall harness off today.  I'll post pictures on the other site.  

1. I had one pin that was low.  I think it was for the brake warning light that I've never seen come on or not sure I have one.
2. One of the pins for the LH Front turn signal was not in the connector at all, the pin did not go through the plug.  
3. Got it hooked back up also figured out I had some wiring wrong with the hood scoop harness.
4. Everything works now.