'55 interior lights flashing

Daves55Sedan

Daves55Sedan

Well-known member
When I pull the headlight switch knob out to the first position all the dash lights AND the parking lights flash on and off at about two second intervals. But if I pull out one more notch for the headlights, the headlamps have steady illumination, but the dash lights still flicker like they did in the park light position. The headlight switch is a repro, but it's a very old one, probably around 20 or 25 yrs old.
It cant be the dimmer, because it does work properly. I don't see how the switch can be at fault because the parking light and interior lights are on different terminals of the switch. Can't be a blown fuse because then the dash lights would not come on at all. ?????
 
Is the HL switch the one with those funky fuses? If so I'd pull the switch out and replace those fuses first. I have an after market switch in my Ford, no fuses on it.
 
Do you have the FORD SHOP MANUAL for the car?

A complete diagnostic routine is in PART 2 - CHAPTER 3 - SECTION 1 (NOV 1954)

The HDL SW has two circuit breakers within- (1) HDL - (2) All Other Lights (other than dome) - (3) - Fuse on rear of switch is for dome lamp(s).

When you say dimmer switch, are you referring to the HDL SW instrument lamp(s) dimmer rheostat or the floor mounted HDL dimmer switch?

I would post the page(s) but FIREFOX decided at some point to interrupt communications.

BTW- If the HDL SW needs replacing, they are still available NOS - B5T 11654-A
 
The headlight circuit schematic diagram in the shop manual is terrible. I am going to re-draw it so it makes more sense. However, I used the parking lights tonight again, but this time there was no flickering of the dash lights or parking lights. The wiring connections on the front fender apron are excellent. Tomorrow I am going to stick my head up under the dash to see if there is any loose wire connections at the headlight switch.
 
Does this headlight switch have a spring looking rheostat to control the dash lights brightness? If so a little WD 40 on the spring and turn knob back and forth several times may get it working again.
 
Maybe the Battery terminal contacts in the switch are getting loose or worn?


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Last edited:
50fordcoupeman said:
Does this headlight switch have a spring looking rheostat to control the dash lights brightness? If so a little WD 40 on the spring and turn knob back and forth several times may get it working again.
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Yes but the dash light dimmer does work fine and is not related to the parking light circuit. That's the conundrum.
 
dmsfrr said:
Maybe the Battery terminal contacts in the switch are getting loose or worn?
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I was thinking maybe the battery wire connection to the switch might be loose, but then if so, why do the headlights NOT flicker. Yet even when the headlights are on the dash lights still flash on and off. It doesn't make sense. I checked the battery wire connection to the terminal on the switch and it is tight and appears to be clean as new.


Maybe something is bad internally inside the switch.
 
Daves55Sedan said:
I was thinking maybe the battery wire connection to the switch might be loose, but then if so, why do the headlights NOT flicker. Yet even when the headlights are on the dash lights still flash on and off. It doesn't make sense. I checked the battery wire connection to the terminal on the switch and it is tight and appears to be clean as new.

Maybe something is bad internally inside the switch.
Click to expand...


KULTULZ said:
The HDL SW has two circuit breakers within- (1) HDL - (2) All Other Lights (other than dome) - (3) - Fuse on rear of switch is for dome lamp(s).
Click to expand...


A bad circuit breaker (or grounding in that circuit) will cause intermittent flashing as the overload causes the breaker to trip and it resets itself as it cools.
 
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