Page 1 of 4

Headlight fix

Posted: 08 Nov 2018 08:21
by bertvorgon
This weekend I am going to try to find out why BOTH my headlights went out suddenly on the last drive.

We did the wire/harness wiggle, could hear the relay working, I had four way flashers and parking lights.

First thing I will check is power to the fuse box for the headlight feed. I sure hope that is all it is, that the wire has broken under the fuse box.

In looking at the wiring diagram, the red power wire taps into the white power wire somewhere in the harness, I hope there is no issue back down the pipe.

Re: Headlight fix

Posted: 08 Nov 2018 17:58
by JasonLee
Good luck with it Keith. It will be nice to get that mystery solved and done with.

Re: Headlight fix

Posted: 08 Nov 2018 19:34
by icehouse
Did you try high beam? The the factory hi/low relay has issues with galvanic corrosion. Most 510's 70-73 don't have high beams due to the relay issue. Maybe you bump the lever into high beam? Since each fuse is for each side of the car it can't be the fuse, or at least less likely. I've also seen the switch fail. Are you running higher wattage bulbs? Maybe your alternator overcharged and blew them out. I had that happen once on a Datto truck I had. Burnt out the bulbs and ruined the relay.

Re: Headlight fix

Posted: 09 Nov 2018 06:10
by bertvorgon
NO high beam either.

I will also check voltage at plug, but to have TWO lights go at once even, I'm not that lucky. I have standard wattage bulbs.

Alternator is fine, I have a voltage meter.

Fuses were fine.

Re: Headlight fix

Posted: 09 Nov 2018 08:17
by icehouse
Okay my guess is the switch at this point. Only other option I can imagine besides the switch is the ground, I can't imagine the ground just braking off for no reason, it also joins with the alternator ground so it's even less likely to loose both.

Re: Headlight fix

Posted: 09 Nov 2018 08:34
by Byron510
When we did a quick check on the last drive - the switching side of the circuit was working fine. I could clearly hear (and feel thanks to the old mechanical part) that the relay was switching from one circuit to the other just fine - at least the relay was working. Checking that the contact point were actually moving power was not confirmed.

Since the relay does switch the grounds in this system, this would have to be verified.
However checking that power was getting to the lights from the fuse box would be a first step. Simply checking at the light plug would confirm this, and working backwards to the fuse box if no power is present.

Once the source is confirmed, then checking of the grounding circuits is necessary.

Keith, you keep you car so damn clean, it wouldn't surprise me if all that washing has affected a ground somewhere in the system :-)

I agree with Jeff, hopefully it's a simple problem to locate and repair. The 510 harness was so simple in the first place and the funny thing is that your 'tech upgrades' themselves have likely doubled the amount of wire in your car! Keep us posted.

Byron

Re: Headlight fix

Posted: 09 Nov 2018 08:42
by bertvorgon
Thanks Guys,.....I feel overwhelmed by what it MIGHT be.

Monday is the day, as I am going to get a 3 day permit and drive to Andy's to check things out.

How..where would one check the grounding circuits?

It was instantaneous when the lights went out, no flicker, just wham..OUT!

Re: Headlight fix

Posted: 09 Nov 2018 12:19
by 510rob
My money is on a failed relay. Easy fix is to replace it with a modern relay clipped into place with an adapter harness.

Just because the relay clicks with power doesn't mean that the high current contact still works.
510 headlight wiring.JPG
510 headlight wiring.JPG (75.31 KiB) Viewed 258 times
1) turn off your headlight switch.
2) disconnect the headlight relay connector from the headlight relay.
3) jumper a wire from the red/white stripe wire (at the headlight relay connector) to some ground on your car (use a piece of 16awg wire for the jumper)
4) turn on the headlight switch and see if the headlights work.

Repeat 1-4 but jumper the red/black stripe wire to ground and see if the other headlights work.

If the lights work, then your problem is either the relay, or the ground that the relay is attached to. But if the relay moves (clicks), then it has some ground.

Measure continuity between the black wire (at the headlight relay connector) to a ground somewhere.

check those and report back.

Re: Headlight fix

Posted: 09 Nov 2018 13:38
by bertvorgon
Thanks Rob!

With meter in hand I will go......plus 5 gallons of gas and ONE match.....

Re: Headlight fix

Posted: 11 Nov 2018 17:35
by Idoxlr8
Iā€™d give up Keith and just sell it to me for what I think is fair.šŸ‘

Re: Headlight fix

Posted: 11 Nov 2018 21:20
by icehouse
510rob wrote: ā†‘
09 Nov 2018 12:19
My money is on a failed relay.
We betting a dinner at our favorite Mexican restaurant?

I've never seen the relay fail in a way high and lows both don't work. The way it's constructed the relay looses connection though the 87b side of the relay, the 87a side as far as I have seen doesn't have an issue. Even my tan car has a "bad" relay I just re-pinned the headlights so only the outsides come on but in "high" mode. haha.

It's gotta be the switch!! Come on! Daddy needs a yummy dinner :)

Re: Headlight fix

Posted: 11 Nov 2018 21:48
by 510rob
icehouse wrote: ā†‘
11 Nov 2018 21:20
510rob wrote: ā†‘
09 Nov 2018 12:19
My money is on a failed relay.
We betting a dinner at our favorite Mexican restaurant?

I've never seen the relay fail in a way high and lows both don't work. The way it's constructed the relay looses connection though the 87b side of the relay, the 87a side as far as I have seen doesn't have an issue. Even my tan car has a "bad" relay I just re-pinned the headlights so only the outsides come on but in "high" mode. haha.

It's gotta be the switch!! Come on! Daddy needs a yummy dinner :)
you are on.

There is a copper braid that bridges the 30 terminal to the floating contacts. That braided lead can, over 40+ years of movement, break!

Then neither path works.

Keith, I might need that relay as proof!!!

Re: Headlight fix

Posted: 11 Nov 2018 22:07
by icehouse
510rob wrote: ā†‘
11 Nov 2018 21:48
icehouse wrote: ā†‘
11 Nov 2018 21:20
510rob wrote: ā†‘
09 Nov 2018 12:19
My money is on a failed relay.
We betting a dinner at our favorite Mexican restaurant?

I've never seen the relay fail in a way high and lows both don't work. The way it's constructed the relay looses connection though the 87b side of the relay, the 87a side as far as I have seen doesn't have an issue. Even my tan car has a "bad" relay I just re-pinned the headlights so only the outsides come on but in "high" mode. haha.

It's gotta be the switch!! Come on! Daddy needs a yummy dinner :)
you are on.

There is a copper braid that bridges the 30 terminal to the floating contacts. That braided lead can, over 40+ years of movement, break!

Then neither path works.

Keith, I might need that relay as proof!!!
Keith we need the proof!!!!!!

Re: Headlight fix

Posted: 12 Nov 2018 08:51
by bertvorgon
In another few hours I will be heading over to get the 510 and zip over to Specialty. I spent an hour yesterday looking at the wiring diagram,
trying to follow Mr. Electron's path.

I really do hope that if it is anything, it will be the relay. To get at my light switch now is a major mining expedition.

I also hope that Tracey has a relay that I just could plug in to try.

Soon we will know.....

Re: Headlight fix

Posted: 12 Nov 2018 09:11
by RMS
if she don't I do. I also have a 73 front harness if its worst case.