Headlight fault!?

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Headlight fault!?

Postby sebwarner1984 » Wed Jan 30, 2019 4:49 pm

Hi everyone. Recently I was driving home from work in the dark. The headlights on my 1979 viva hc 1256 leave a lot to be desired however you soon appreciate what you have when they go out suddenly!!! This is what happened to me and it gave me the fright of my life when I think back to the winding country lane I had just come off. Had I been there I would have been in a serious car accident!! I first checked the earth connection for the headlight system which I sanded up and made good. However this has now happened another 3 times.
A garage has had a look today for me but come back with no definite reason. He has suggested it could be the switch. Has anyone else had this issue?? Can I get a switch anywhere?? Thanks in advance for your input :thanx:
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Re: Headlight fault!?

Postby droopsnoot » Wed Jan 30, 2019 7:30 pm

If your wiring is standard, you have a thermal cutout switch under the dash (mounted on the inside of the drivers door pillar) which will cause the lights to go out if the circuit is overloaded. When it cools down, they come back on again - it's a bimetallic strip, which is used in preference to a fuse just so it can reset itself.

As for the cause, do you have any higher-than-normal-spec bulbs fitted anywhere? If not, then it may be a poor connection somewhere that is increasing the load and causing the thermal cutout to trip.

(All the above is presuming they come back on their own).

Given that wiring itself can deteriorate over the years, you could also consider a relay circuit to take the load off the old loom and use new cabling for the high-current parts.

I guess it could be the switch. If yours is the centre console switch I know they can be dismantled, cleaned and reassembled.
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Re: Headlight fault!?

Postby 1972nail » Wed Jan 30, 2019 7:40 pm

As Mike says, the thermal cutout is probably tripping and resetting. The switch is probably the culprit causing the high load on the cutout. It will be a twin dial switch and they can be taken apart and cleaned with a bit of care. Reassemble with a bit of electrical contact grease.
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Re: Headlight fault!?

Postby sebwarner1984 » Wed Jan 30, 2019 9:32 pm

Thanks guys that’s certainly a direction I haven’t been down yet so well worth checking it out. My mechanic did say he tried to open up the switch to see if you could use a connection cleaner but couldn’t. However my two dial dash as you say should allow me to open it up. I’ll ask him to try again or I will. :thanx:
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Re: Headlight fault!?

Postby dann01 » Thu Jan 31, 2019 12:12 pm

I usually only suffer from this during a long trip, and have to agree that being plunged into complete darkness while driving is absolutely petrifying.

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Re: Headlight fault!?

Postby jpsmit » Thu Jan 31, 2019 2:15 pm

dann01 wrote:I usually only suffer from this during a long trip, and have to agree that being plunged into complete darkness while driving is absolutely petrifying.

Dan


Possibly a time to consider relays for the headlights - many benefits including bypassing the thermal switch, brighter lights and an easy and reversible mod.
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Re: Headlight fault!?

Postby sebwarner1984 » Thu Jan 31, 2019 3:52 pm

Possibly a time to consider relays for the headlights - many benefits including bypassing the thermal switch, brighter lights and an easy and reversible mod.[/quote]


I think you’re right of this can be done relatively easily and can give me brighter lights then I’m happy with that. :goodideasign:
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Re: Headlight fault!?

Postby Kraken » Thu Jan 31, 2019 10:34 pm

I have had a slight issue with the switch in my HC. Not sure if they are the same in later HCs (mine is mounted just in front of speedo). If my switch is pressed on too hard/far then I get a slight issue.

Thankfully I found this out whilst parked up!
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Re: Headlight fault!?

Postby 1972nail » Thu Jan 31, 2019 11:31 pm

Yes, they are the same type of switch.
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