2015 turn signal switchback bulb issue

[omar302]

@TheWizard

Saw that too, good point. I would also say you're probably right, but disconnecting the parking light input from the headlight would also kill the side marker. 

[Nick Halstead]

9 hours ago, TheWizard said:

But you're right - there is no plug-and-play way to make switchbacks work.

through time and money, we can make all kinds of things work most people (on this forum) aren't too keen on getting off the straight plug n play modding field.

[TheWizard]

11 hours ago, omar302 said:

@TheWizard

Saw that too, good point. I would also say you're probably right, but disconnecting the parking light input from the headlight would also kill the side marker. 

 

Yes, that could be a problem.

 

There's another possibility... the schematics don't show the internal workings of the headlamp assembly but they do show that there are three separate ground wires on each side.  I wonder if instead of disconnecting the input power it might be possible to disable the parking light by disconnecting one of those grounds?  It's a long shot but might be worth a try if someone has the time (and inclination) to experiment.  Testing could be done with jumper wires rather than modifying the factory wiring (unplug the connector and run small sections of wire (or even a test light) between the connector pins and a chassis ground point.

 

[omar302]

On 12/6/2018 at 4:31 PM, TheWizard said:

 

Yes, that could be a problem.

 

There's another possibility... the schematics don't show the internal workings of the headlamp assembly but they do show that there are three separate ground wires on each side.  I wonder if instead of disconnecting the input power it might be possible to disable the parking light by disconnecting one of those grounds?  It's a long shot but might be worth a try if someone has the time (and inclination) to experiment.  Testing could be done with jumper wires rather than modifying the factory wiring (unplug the connector and run small sections of wire (or even a test light) between the connector pins and a chassis ground point.

 

 

Found out how to do it. Stumbled on the below video, just did the opposite and worked. Basically, the ForScan changes are (from the 2015-18 F150 sheet):

 

726-29-02

xxx*

xxxx

xxxx

Front Turn Position Lamps Cfg: 0=Turn_Only, 1=Turn_Position Edit to explain: 0: (stock) The front signal bulb will function as a turn signal bulb only. 1: The front signal bulb will function as a turn signal (at full brightness) and as a parking light (reduced brightness)

 

Now with the ignition/engine on i have the small LED side markers on & the signature lights on the bumper. Now the issue with this is when turning the parking lights on with ignition/engine off, the signatures lights don't come on, so there would only be the LED side markers.

 

 

Edited December 8, 2018 by omar302

[tmarsh]

On 12/5/2018 at 2:11 PM, TheWizard said:

Good point! However, I have downloaded the lighting schematic and it shows separate wires at the headlamp assembly for turn signal and parking lights.  I don't have an Edge of this year to look at but I wonder if the two inputs are managed within the headlamp assembly to control the single filament bulb.  The schematic shows a blue/green wire as turn signal input at the left headlamp and a yellow/purple wire as turn signal on the right side.  Both sides have a separate blue/gray wire for parking light input.  That would mean that disconnecting the blue/gray wire on each side should prevent parking light activation in the bulb and allow the separate wire on the switchback to control the white circuit.

 

 

I thought this too, not the case. The BdyCM controls voltage to the turn signal, there is no inner workings to the headlight assembly. The parking light wire in the headlight connector is only for the side marker. The turn wire goes straight through to the turn signal bulb to supply it with the two voltages for marker and turn.

[TheWizard]

That's what I expected after omar302 mentioned that disconnecting the parking light power wire disabled the marker light.  It made more sense that the lowered voltage was coming from a computer module rather than being handled inside the headlight housing.  Thanks for confirming that. 

 

At least the ForScan changes provide a nondestructive (and reversible) method of achieving the desired results.  That means that one of the 7443 sockets with a separate white side power wire could be used to make switchbacks work.