Headlight Relays

Got a headsup for you folks. Last night I accessed and cleaned the contacts in my dimmer switch again. I've had to do this twice now since buying the car in October '99. My high beams eventually fail to come on because of the burnt contact. Lows still work and flash still works.

In performing this contact-cleaning maneuver I noticed that some of the wires and terminals also look burnt. Two of the wires going form the light switch to the dimmer switch are very noticeably darkened.

I then checked to see if maybe the PO had installed the brighter (100w) bulbs without using a relay, causing the overcurrent problem. The answer is no. They are 55/60.

Okay, the point is this: Our light switches and relays will not comfortably handle all the current going to the headlights, even if you don't have super duper bumper melting lights. I'm sorry to have to say this, but Porsche erred in choosing not to use relays for this system.

I don't want to have to buy a new dimmer switch ($125 or so) and I do want to melt bumpers, so I plan to get some 100w bulbs. Even if I stayed with the 55/60 bulbs, the relays are still necessary.

My favorite local parts guy sold me two today for $10 each. Bosch. I believe this may also be available at this (Pelican) site.

I'm only posting this because it looks like this part of the electrical system in YOUR CAR is borderline dangerous not to upgrade and the fix is easy and inexpensive. Do it.

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'83 SC

Super,

I came to the same conclusion as you several years ago, but most people tend not to believe me on this issue, insisting that I am being an alarmist. My relays are also Bosch, of the DIN ice-cube variety, and have a nice green plastic housing, but they came from a surplus electronics supplier, and hence were only $2.95 each, but there were only a limited supply avilable when I got them, so I have to buy in advance of my needs!

The mod I chose to do uses four relays, one for each headlamp filament, but has the additional benefit of being modular for each side of the car, and no wires are cut anywhere in the vehicle! There was even an unused screw terminal on the battery positive connector, where I could attach 10 gauge cables to each headlamp bucket, fused at 30 Amps for each side! I also wired an optional switch on the dash to illuminate all four beams simultaneously whenever the flasher is used, or have the high beams turned on!!! Besides burnt paint, my purpose is to burn the retinas of the idiots who pull in front and then immediately hit the brakes!

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Warren Hall
1973 911S Targa

Well, I'll consider whether I need to use four relays and I'm guessing I do not, but the direct wiring to the battery positive terminal sounds like a plan. The always-hot power supply has an inline fuse (didn't notice how many amps), so I don't have to be concerned about unfused wiring.

I'm not gonna beat the horse I killed above, but the cabling under my dash is very notably darkened at the connections. I am very convinced this is a MUST upgrade.

Thanx, Warren. Of course, I'll probably have questions for you as I look into this. by the way, in case you have not guessed, I'm a 'button on the dash' guy too. My car is bone stock and unmolested, so far, but I commonly consider things like a switch taht will run the heater fan, or shut it off. It is a vulnerable motor and not needed except during the first few miles of travel on cold mornings. Later.

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'83 SC

Hey! Part numbers and some instructions would be very helpful to a know-nothing like myself. Mind you, I am still trying to master the electric can opener...

Very interesting.

I was having a problem a couple of months ago where my headlights suddenly stopped working, both high-beams and low-beams. It took a bit of digging to finally isolate the problem to my headlight switch. The terminal that sends power to the headlights was dead. I had recently installed new H-4's, but they were the same 55/60 that were removed.

I am with Super, I think that in my case, the new bulbs were drawing heavier voltage than that switch could handle.

p.s. By the way, Warren was right again. He pointed towards the switch as the likely culprit. I was in doubt, but a simple continuity tester located the problem.

Thanks!

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John
73 911S

Don, I'll bet you thought I forgot. Teh part number on the Bosch relay is 0 332 019 150. Came in a bag with the wiring harness (plug, four beautiful wires, one with a 15A fuse). Warren uses four and I may need one for each highbeam. I believe there must be several kinds available as mine actually seems to be a starter relay setup, but this will be a minor modification.

This contraption is widely available, Don, and you likely can find them easily both and good local VW parts places or on the internet, probably at Pelican. I paid $10 each for two, and I may need one or two more. I think I'll also go crazy with the shrink tube and stuff.

I hope you're not offended as I say: The relay is a switch. It sends power to something when it gets power from another switch. So you mount the relay somewhere near your headlights and your battery and fusebox. Then you take the wires coming from the dash switches and hook them to the relay so it knows when to send power to your headlights. This way, high power, such as for headlights, does not have to go through your weak and expensive dash switches.

Power goes though both your light switch and your dimmer switch on its way to power the headlights, right now, and mine. Those of you still listening, look at the back of your main light switch. I'll bet you've got burnt looking wires there. They go to the dimmer switch. Nuf said.



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'83 SC

THANKS !!! only one question left... Which wire off the switch to I use??? It's hell to be this dumb...

Don & Super Jim,

The logical pickup point is at the fuse block, fuses 5-8, which lie electrically 'between' the switching circuitry on the dash and steering column ... and the headlamp assemblies! One fuse per filament ... one relay per filament is cheap and too easy to ignore! Local parts stores have 30 Amp relays for $4.99 (with driving/fog lighs and accessories) and circuit breakers that can replace fuses, too.

Or, you can find 40 Amp relays and sockets at this source:

http://www.hosfelt.com/Relay%20Folder/Relay%205.htm

Power leads to 100 Watt (or larger) bulbs should be 12 or 14 ga wire, and the common ground lead on H1 or H4 assemblies should be 12 ga!

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Warren Hall
1973 911S Targa

I'm still cogitating over this one, Don, so it very well may be weeks before I assemble the parts with an action plan. The relays will be easy to install and they'll go somewhere near the fuse box, I believe.

I may replace some conductors, like Warren suggests, because I do plan on using 100w high beams and I believe his assertion that 12 gauge wiring is needed. So I'll know exactly which wires to deal with, but just not yet. I'll keep you posted.

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'83 SC

U da Man!!!

I once played in a charity golf tournament for both advertising purposes and the charity is a good one. You just show up at the appointed time and you get put in a group of players. I was grouped with 4 women. Of course this did not bother me in the slightest. Every time I teed up my ball, all four members of my group appropriately yelled U DA MAN. One of the women is a pro and we won the tourney.

They all liked my car even after watching me go through the routine of stategically placing my metal driver so it will not touch the battery terminals.

A new golf club placement will have to be devised to avoid touching the relays thay I am now going to install near the headlights.

I am working on my 2nd dimmer switch in 4 years. Now I know why.
David

[This message has been edited by DAVIDM (edited 12-17-2000).]

David,

If you take a look at the web page I posted as a source, immediately below the relay is a socket which has been prewired with 24" leads, and its use would eliminate any exposed wires that could be contacted by any metal objects in the trunk. The relays also have some nice mounting tabs that can be used to secure the relays in place!

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Warren Hall
1973 911S Targa

Warren's got a message here. that place is gonna sell me shrink tube and connectors very soon.

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'83 SC

Okay: someone explain what a relay does then...I thought a relay delayed the current flow until the voltage was high enough, then let it through. How does this prevent the melting of the headlight wiring?

Just curious...I've just rewired my interior, trunk, and glove compartment lights, and it was a pain in the ass, and the last thing I'd want is anymore electrical problems!

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Kurt B
1984 911 Carrera Cabriolet
75 914 1.8

Kurt -- think of a relay as a remote control switch. The light switch on your dash is used to "energize" the relay. The relay then switches the headlight on. The advantage is that the relay carries the high current needed to drive the headlights, while the light switch on your dash carries only the current requried to turn on the relay.



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Bill Krause
'79 911SC Euro

Indeed. kurt, my 12-16 post has another brief explanation. Bottom line: With the relay system, the heavy currents needed to power the headlights will flow through the relay without flowing through the dash switches. Those heavy currents are what is killing our dimmer switches and to a lesser degree, our light switches as well.

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'83 SC

Is 55/60 watts really any, if at all, more than what came stock with the car? It would surprise me if the stock lights were less than 55w.

I ask this because my SC has had H4s with 55/60 watt bulbs in them for more than 10 years, with no add on relays, and I've never had any problems with the wiring, switches or anything else.

I've also had Hella H4s in just about every late 70s and early 80's German car I've ever owned, and have always been told that the wiring is sufficient to handle them, and have never had a problem.

I would be curious to know how the US light wiring is different, if at all, from the Euro wiring system (they Euro cars have used H4s/H1s for years). Is there a relay in the Euro car wiring?

Just my experience, FWIW.

Gotcha guys: thanks for the speedy replies. It is time for me to examine those dimmer wires then, and ensure that mine are in good order. If they are dark, fried, or in any way molested, I'll slap in a relay!

Now, I understand what happened to my 914 wiring. It was caused via the fog lights. I major burnout sent em all smoking one day...

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Kurt B
1984 911 Carrera Cabriolet
75 914 1.8

certainly would think you don't need relays on your car, with its stock headlights . . .

Whats the best kind of lights to buy. I have a 89 911. I want that M-Benz cool look on the newer cars. Is that a super-white or cool blue? Is that require a higher wattage than normal? Do we need the relays on the 89? Can we buy some good lights at the local parts store or does this require bulbs that can only be bought through Pelican or alike stores?

Mike Miller
89 911