The headlamps are controlled by the Front Electronic Module and instrument cluster. The headlamp and multifunction switches are hard-wired to the instrument cluster. When the headlamp switch is in any position, the instrument cluster sends a command to the FEM through the communication network. The FEM processes this information and outputs the appropriate command to the headlamps (which are hard-wired to the FEM). This is the same for the low beams, high beams and flash-to-pass position.

To answer your question, both the high and low beams receive voltage from the Central Junction Box. The FEM supplies the ground to complete the circuit and illuminate either the high or low beams.

doug7740
1955 Thunderbird Blue

Headlamp Circuit.jpg
 
Here is where I send my control modules to be rebuilt.


doug7740
1955 Thunderbird Blue
 
The headlamps are controlled by the Front Electronic Module and instrument cluster. The headlamp and multifunction switches are hard-wired to the instrument cluster. When the headlamp switch is in any position, the instrument cluster sends a command to the FEM through the communication network. The FEM processes this information and outputs the appropriate command to the headlamps (which are hard-wired to the FEM). This is the same for the low beams, high beams and flash-to-pass position.

To answer your question, both the high and low beams receive voltage from the Central Junction Box. The FEM supplies the ground to complete the circuit and illuminate either the high or low beams.

doug7740
1955 Thunderbird Blue

View attachment 28975

To test the circuit, is it okay to put a temporarily jumper to ground on the #3 BLK/RED headlight wire to see if the high beam will come on?
 
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Davy did you ever find a cure for your problem, it’s sounds exactly what’s going on with my 2004. Any input would be appreciated
thanks Joe Dawson
 
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To test the circuit, is it okay to put a temporarily jumper to ground on the #3 BLK/RED headlight wire to see if the high beam will come on?
Yes, if you back probe terminal #3, BLK/RED headlight wire, and jumper it to ground the high beam should illuminate. Fuse #9 of the Central Junction Box supplies voltage to both the high and low beam headlight bulbs, but you stated that only the low beam bulb had voltage and there wasn't any voltage at the high beam bulb. If that is true than there is an open circuit at the junction point inside the right headlight.

doug7740
1955 Thunderbird Blue

Open Circuit.jpg
 
2002 no dashlights, shifter indicator lights or lights on steering wheel. Whats the problem?
 
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it seems all connected: the windows wont drop and rise when opening/closing the doors anymore. at first sometimes they would sometimes they wouldn't which is strange .now they dont at all. the horn stopped blowing and then started again, then stopped again. the steering wheel can rise & lower, come toward you but not go back in. the driver side window wont lower even when pushing the button now.. im not going to attempt lowering the ragtop anymore in fear it wont come back up, it was stopping last time i did. The last mechanic i took it to said hydraulic fluid and other fluids were fine. other than that no mechanic wants to touch it, say it would take too many hours to find a diagnosis but they are honest they arent familiar with working on these at all. even at the ford dealership they said their mechanics have no knowledge of these and are only trained on vehicles 2012 and up.
 
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it seems all connected: the windows wont drop and rise when opening/closing the doors anymore. at first sometimes they would sometimes they wouldn't which is strange .now they dont at all. the horn stopped blowing and then started again, then stopped again. the steering wheel can rise & lower, come toward you but not go back in. the driver side window wont lower even when pushing the button now.. im not going to attempt lowering the ragtop anymore in fear it wont come back up, it was stopping last time i did. The last mechanic i took it to said hydraulic fluid and other fluids were fine. other than that no mechanic wants to touch it, say it would take too many hours to find a diagnosis but they are honest they arent familiar with working on these at all. even at the ford dealership they said their mechanics have no knowledge of these and are only trained on vehicles 2012 and up.
I merged your post with and existing topic that already answers your question. Start reading on page 1.

 
This happens on and off , headlights flicker, then go out, along with tail lights and dashboard-speedo. Turn signal indicator on the dash still works. Super dangerous, as during daytime driving I believe my signals are working..... Problem solves itself eventually, until next time. Where to start troubleshooting?
 
This happens on and off , headlights flicker, then go out, along with tail lights and dashboard-speedo. Turn signal indicator on the dash still works. Super dangerous, as during daytime driving I believe my signals are working..... Problem solves itself eventually, until next time. Where to start troubleshooting?
Sounds like the issue is on the side of the positive fuse box that is not on the ignition switch. If it was a grounding issue then the whole vehicle would be affected. Also, it seems as though none of the lights that run through the computer are affected. I would be looking for a wiring issue between the battery and fuse box. Turn on the headlights and start jiggling.
 
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