Hi Beam Warning Light

[KiwiJohn]

I am getting a fail on my 6 month inspection for the lack of brightness of the hi beam warning light.
This is the blue light dot in the tach.
I have pulled the bulb and tried to clean the lens with a soaked rag on the end of a pencil.
Shining a torch from the back shows a pretty strong blue light.
The bulb is 1.2watts so I am not expecting miracles.
I was considering a LED bulb as a replacement. However the voltage at the bulb holder is only 10.5v.
Should it be 12v? And where would I look for the missing volts?

[spuggy]

Originally Posted by KiwiJohn

I was considering a LED bulb as a replacement.

That'd probably help. Could be a useful stopgap.

Originally Posted by KiwiJohn

However the voltage at the bulb holder is only 10.5v.
Should it be 12v?

Yes, unless you have the uber-rare M480 "low voltage system", in which case you should replace all your bulbs with the Porsche-branded 10.5V bulbs all round.

heh - only kidding

It's a 12V system... Should read close to battery voltage - so more like 13.5, 14V with the motor running.

Originally Posted by KiwiJohn

And where would I look for the missing volts?

Bad grounds (there's like 17 of them), switch, connection. If your other instrument bulbs are reading a lot closer to 12V, then it's probably the tiny little contacts on the headlight stalk switch are burnt/pitted for the main beam position; clean (allegedly this is possible) or replace the stalk.

Either way, fit headlight relays, so all the current through the tiny little contacts doesn't just do it again...

[KiwiJohn]

Lots of great info there spuggy!
Thank you very much for that.
Plenty for me to work on. Thanks again.

[86 911 Targa]

^^^^
Here's the circuit.(M/Y '86).

Should be the same as your M/Y
with different wire color codes.

I'm also with the "bad ground" theory.

Good luck,

Gerry

[OldSpool87]

FWIW the LED option (vintage hue) is a nice and easily reversible upgrade. Lots of info on the forum.

[HarryD]

Try a new bulb. Much of the darkness is inside the bulb.

[KiwiJohn]

Thank you all for the very useful suggestions.
I remain in awe of the "Peliknowledge" demonstrated daily here.
The good news is that common sense has prevailed at inspection and they realised that a 40 year old car is going to show its age in places without compromising safety.
Passed
Incidentally the inspection requirements in New Zealand, are, for a vehicle first registered before 2000, it needs a 6 monthly WoF (Warrant of Fitness). Regardless of mileage run over the period.
Vehicles first registered anywhere in the world on or after 1 January 2000 need annual WoF inspections for their lifetime. For new vehicles, after an initial inspection, another WoF inspection won't be required until the 3rd anniversary of their first registration.
Cost for the inspection is about NZ$50.
However I do intend to investigate further to avoid grief again in 6 months.
Bad grounds and/or switch contacts seem to be the popular choice.

FWIW the LED option (vintage hue) is a nice and easily reversible upgrade. Lots of info on the forum

Thanks for that OldSpool87 but I was thinking of a white LED and leaving the blue lens in place.

[OldSpool87]

Originally Posted by KiwiJohn

Thank you all for the very useful suggestions.
I remain in awe of the "Peliknowledge" demonstrated daily here.
The good news is that common sense has prevailed at inspection and they realised that a 40 year old car is going to show its age in places without compromising safety.
Passed
Incidentally the inspection requirements in New Zealand, are, for a vehicle first registered before 2000, it needs a 6 monthly WoF (Warrant of Fitness). Regardless of mileage run over the period.
Vehicles first registered anywhere in the world on or after 1 January 2000 need annual WoF inspections for their lifetime. For new vehicles, after an initial inspection, another WoF inspection won't be required until the 3rd anniversary of their first registration.
Cost for the inspection is about NZ$50.
However I do intend to investigate further to avoid grief again in 6 months.
Bad grounds and/or switch contacts seem to be the popular choice.

Thanks for that OldSpool87 but I was thinking of a white LED and leaving the blue lens in place.

No sweat. FWIW most led gauge sets come with clear leds for the jeweled lights like high beam indicators.

Glad it all worked out for you.

[spuggy]

Originally Posted by KiwiJohn

Passed

Cool, the jobsworth saw reason...

Originally Posted by KiwiJohn

Bad grounds and/or switch contacts seem to be the popular choice.

Work the problem; if voltage at the bulb holder and the battery terminals is the same, there's nothing wrong in the wiring/switches. But if you've got a measured drop between the battery terminals and the bulb holder, then the problem is between the two; you can't get voltage out of a switch that isn't going into it...

A bad ground can cause the circuit to ground over (and possibly overload) some other circuit it wasn't intended to.

If you've got 10.5V at the battery with the motor running, that's a different problem


It's generally under-appreciated the effect voltage drop has on light output, and how this is caused by resistive load due to thin wiring or switch contacts. Here's some food for thought (yeh, talking about headlight output - but the physics is the same), from an automotive lighting consultant: https://www.danielsternlighting.com/tech/relays/relays.html

Power for the headlights is controlled by (wait for it) the headlight switch. In almost all vehicles built through the late '90s, and quite a few built after that timeframe, all headlamp current runs through the switch. That is: long lengths of thin wire to and from the switch, which contains tiny contacts. All of this adds up to a surprising amount of resistive voltage drop, which takes a big bite out of headlamp output.

In many cases, the thin factory wires are inadequate even for the standard original-equipment headlamps. There's a large element of automaker cost-cutting involved; it might sound like a joke to say they figure headlamps are only used at night, so that's a 50% usage duty, so they cut the wire gauge in half, but it's actually pretty close to how these kinds of decisions are often made in the auto industry where just about every last fraction of a cent that can be shaved from the build cost, will be.

And science has yet to give us the wiring, connections, and switch contacts that improve with age; in fact they do the opposite.

Headlamp bulb light output is severely compromised with decreased voltage. The drop in light output is not linear, it is exponential to the power 3.4.

10.5V : 510 lumens
11.0V : 597 lumens
11.5V : 695 lumens
12.0V : 803 lumens
12.5V : 923 lumens
12.8V : 1000 lumens ←Rated output voltage
13.0V : 1054 lumens
13.5V : 1198 lumens
14.0V : 1356 lumens ←Rated life voltage
14.5V : 1528 lumens

With headlight relays, my stock-wattage H4's went from bright yellow to white. Still want to uprate the wiring harness to the bulbs...

Not only are headlights brighter with relays, using them takes 10 amps[*] out of that path through the dash and stalk switches - which only makes their life easier/longer. Try feeling the back of the dash switch when the headlights have been on a few minutes... These are not cheap to replace.

[*] 2 x 60W = 120W @ 12V == 10A

Also, check for a fuse on the dash illumination (fed from terminal 58 on the headlight switch, IIRC). If a PO didn't already add one (if they did, you probably want to know where it is), just take a moment to consider what the aftermath of a fire in that harness would look like. An in-line 2A fuse would be easy to add while you're poking about back there with a multimeter...

Originally Posted by KiwiJohn

I was thinking of a white LED and leaving the blue lens in place.

Most places that supply replacement LED's advise a colored LED to match the lens color.

I've had eTarga's "classic" (tried the bright first but found it too "cold") gauge LED set in the car for years; my hi-beam indicator verges on distractingly bright, to the point that I've considered swapping that LED out for a cheap generic lower-output one... I do like the other warnings being in-yer-face bright though

[wreckah]

Originally Posted by KiwiJohn

The good news is that common sense has prevailed at inspection and they realised that a 40 year old car is going to show its age in places without compromising safety.
Passed

i was going to say...not passing for a 'not bright enough' gauge warning light? that would be ridiculous...not one oldtimer would get through over here if that would be the case.
I hope they check the less important stuff too, like brakes and tires and such

[JSV798]

The feed for the main beam warning light comes from fuse 8 (wt/bl cable) so the current has already had to travel from the battery to the headlamp switch back to the fuse before returning to the warning light. If you up rate to relays you will cut out the first part of this so that current for the warning light has to travel only from the fuse. Therefore it should be brighter.

[KiwiJohn]

Originally Posted by spuggy

If you've got 10.5V at the battery with the motor running, that's a different problem
With headlight relays, my stock-wattage H4's went from bright yellow to white. Still want to uprate the wiring harness to the bulbs...
Not only are headlights brighter with relays, using them takes 10 amps[*] out of that path through the dash and stalk switches - which only makes their life easier/longer. Try feeling the back of the dash switch when the headlights have been on a few minutes... These are not cheap to replace.

OK ..Relays it is then. I have searched for some sort of how to on this. Any Ideas?

Originally Posted by spuggy

Most places that supply replacement LED's advise a colored LED to match the lens color.
I've had eTarga's "classic" (tried the bright first but found it too "cold") gauge LED set in the car for years; my hi-beam indicator verges on distractingly bright, to the point that I've considered swapping that LED out for a cheap generic lower-output one... I do like the other warnings being in-yer-face bright though

I am not going to replace the dash lighting with LEDs. Although the voltage at them is lower than 12 with the rheostat turned right up. Will look for a blue LED.

Originally Posted by wreckah

i was going to say...not passing for a 'not bright enough' gauge warning light? that would be ridiculous...not one oldtimer would get through over here if that would be the case.
I hope they check the less important stuff too, like brakes and tires and such

I'm glad you also see this as ridiculous. When I returned for the recheck, I was served by a different inspector. One who has done the Porsche for me numerous times over the years. He did not, of course, ridicule his fellow worker, but a slightly incredulous shake of the head when he read the fail sheet spoke volumes

[Arne2]

Originally Posted by KiwiJohn

Will look for a blue LED.

I got a single blue LED from etarga for my '84. Just the blue one for the high beam, none of the rest. Cost was $8, but that was 7 years ago. Doesn't look like he is around anymore. So I think I'd shoot for something like these - https://www.superbrightleds.com/moreinfo/ba9s-ba7s/ba7s-led-bulb-1-led-ba7s-retrofit-car/10/

[spuggy]

Originally Posted by KiwiJohn

OK ..Relays it is then. I have searched for some sort of how to on this. Any Ideas?

Multiple ways to do it, depending on how you weight cost, your time, looks factory - or if you value function over everything else.

You could buy the round Porsche relay sockets and do this yourself using the unused relays in the fusebox panel. Timmy2 on here can mould up round relay sockets on request with heavy-duty wires, so can gang hi/lo beams into a pair of relays (most cars have a couple of spare spaces). Ultimate factory look.

The only real fly in the ointment with that approach is that you can't buy decent round relays anymore; they're all made in China, cheaply. And solid-state Bosch-type 40A Panasonic relays are about 1000x better @ $3 a pop, as opposed to iffy junk for 10x the price...

You could build the relay bases yourself, sourcing your own components.

Daniel Stern headlight relay assembly and installation thread, or buy a kit to save you crimping/assembling the pigtails e.g.: https://www.pelicanparts.com/More_Info/JWST-911-HLPR&SuperCat=Y&SVSVSI=1012.htm

They get installed the same: JWest headlight relay kit question

Or replace the antiquated (and frankly, worrying if you look at it closely) fuse panel with a modern one that takes ATO fuses and comes with integrated headlight relays. Looks stock until you take the fuse cover off.

https://www.pelicanparts.com/More_Info/911-FPR&SuperCat=Y&SVSVSI=1012.htm
Review: Classic Retrofit Porsche 911 Fuse Panel
Classic Retrofit upgraded fuse panel for Porsche 911s from 1974 to 1989

Very nice piece. Works great.

[wreckah]

Originally Posted by KiwiJohn

I'm glad you also see this as ridiculous. When I returned for the recheck, I was served by a different inspector. One who has done the Porsche for me numerous times over the years. He did not, of course, ridicule his fellow worker, but a slightly incredulous shake of the head when he read the fail sheet spoke volumes

what people do in Belgium: they go to the MOT, get failed for let's say wrongly adjusted headlights (even though they come straight from their mechanic who has just adjusted them.)...they drive 5 minutes around the block, they re present their vehicle at the station, get another inspector hopefully, and get passed.
in our case, it's maffia, bored government personnel (let's fail all alfa romeos today) and money making...but your fail takes the cake.

[bkreigsr]

How long before you are exempt from inspection?
NZ still inspecting after 40+ years?
Bill K

[KiwiJohn]

Originally Posted by bkreigsr

How long before you are exempt from inspection?
NZ still inspecting after 40+ years?
Bill K

Sadly..Yes

[Duc Hunter]

I dropped LED in my Rat Rod. Vintage color for all the gauge lighting, but NON-Vintage for the warning lights, like the high beam. Seemed brighter to me. I dont miss mine now at all!

[Arne2]

A blue LED will be much brighter with the darkened blue lens than a white LED. The blue LED in mine took it from invisible at night to very noticeable in daytime.

For reference, a blue lens doesn't tint the light blue, it filters all non-blue wavelengths out. So the blue lens lets virtually all the blue LED light pass. A white LED has very little dark blue wavelengths, so the output is quite dim.

This is why LED makers all tell you to match the LED color with the color of the lens. Same is true for red, amber or whatever. Colored lenses are filters.

[Bill Douglas]

John, on the WOF check sheet there isn't a box to tick regarding brightness. It either works or it doesn't, and in your case it does. Talk to Land Transport about your issues with the inspector.

If you live in Wellington I may have another solution for you.