Dash light issue

[booah]

Hi all,

Here's the issue: 1970 mach 1
When the car is cruising along on the freeway or or on the suburban roads, all is well.
As soon as I come to a stop, the dashlights turn off and I can hear a relay click. Then the turn back on again and so on it goes until I start moving and get the revs up.

Thought it might be because of the revs and the voltage reg etc, but while parked if I rev the engine the dashlights want to turn on and off still. The sport lights also turn on and off at the same time.

Could it be a weak relay?


any ideas?

[scott66stang]

That sounds very much like a faulty head light switch , they have a Bi-metal strip inside them which heats up and breaks contact untill it cools and recontacts when overloaded. Your high beam is proberly drawing too much current , suggest fitting a relayto the headlights especially if they are halogen.. This also turns the dash lights off and on.

[booah]

Thanks, I did just change the bulbs too.......ummmmm

[seany-boy]

on full beam or low as well? I have been lucky (touch wood) so far in that they seem to work ok on low beam but high beam they say 'goodnight' as you describe. I know I have to get relays - just still looking for a round tuit!:w

[booah]

The cutting out of the dash lights is on low beam. It has a relay but it is one relay for both the hi and the lo beams and looks like it came from noah's arc.

 Am going to change back to the lower intensity lights for tonite and see how it goes. if OK then I'll get different relays??

[booah]

Well same thing happens with the old bulbs. I'll look at putting relays in and a light switch.

Any other thoughts??

[seany-boy]

Have you checked out you headlight switch? If the same as in the 70, the dashlight have the dimmer 'coil' on the back. Mine was dirty, corroded poor tension etc so had to clean it up and 'adjust' it a little. But if it is all the lights including sports then perhaps the internals of the headlight switch is faulty as scott66stang mentioned.

[scott66stang]

I was wondering the same as seanyboy , If it was just the dash lights i would say it was just the dimmer on the light switch.  But another thought would be what is the spotlight relay wired to , possibly the dimmer switch or dash light wire or fuse? not a good option but easy to pick up the wrong wire as it would have power when the lights are turned on.

[moe]

out of curiosity, was there any voltage drop from the alternator at idle?

[booah]

Ok I'll look at the way the sport lamps are wired up. They come on with the headlights, there was no seperate switch for the lights.

Its been converted to RHD back in the olden days and wiring is not pretty.

I also replaced one of the sport lamp bulbs(burnt out), maybe just enough draw to cause havoc now?

[seany-boy]

also just a thought, when did it start doing this or always been doing it?

[Frank70]

There should a switch for the sports lights.

So I would say it is either those or the light switch as the others have suggested.

I have a spare light switch that is a bit crusty but essentially works if you are in Melbourne.

Cheers,
Frank.

[booah]

Thanks for the offer Frank, but I'm in Perth. I'll take this one apart first and see what I have.

I'll check the voltage drop at the alternator too.

I was looking for the original sportlamp switch but their as rare as hens teeth, if anyone has a spare, let me know.

[moe]

could try Barry at early pony parts, might have a lead on a switch.

[seany-boy]

they are very rare, I saw this on ebay and it looks identical to my sportslamp switch- obviously different label- but not sure if they are actually the same. It may still go for the same money but maybe worth watching or seeing if he has a buy it now price in mind if you think it would work
http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&item=230384777879

[booah]

Thanks Sean, I'll watch it. Haven't had a chance to check any of the above yet but will let everyone know when I get it resolved.