Help with headlight/driving light rewire project

Stevehose

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3) I didn't add heavier gauge wire but cleaned all wire/light contacts thoroughly. Big difference after relay installed.

4) If you PM me your email address I will send you a 72 e9 pdf diagram.

Sorry can't help with the first 2 questions.
 

HB Chris

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The Hella reflectors can discolor after time, one of my H1s turned frosty and I replaced it. Use Steve's diagram, terminal 30 is power from battery, 87 goes to the lights, 85 and 86 are the trigger from hi/lo switch and ground, doesn't matter which is which. I didn't change any wires but they are kinda thin, 16g I think. In 74 BMW upgraded the wires I believe and added fuses and lo beam relay.
 

afeustel

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FUSE Size for High Beam and Horn Relay

Installed a relay for the low beams on the E3 and also fused the direct power from batt terminal to all three relays.

Question is what size Fuse are folks using for the relays? I have a 15 amp in the new low beam circuit which seems to be fine (i.e. it works well and did not blow fuse). However, the 15 amp installed for the high beam and horm relay (these are on a common power line) blew immediately upon activation.

If I apply direct power from + batt to the #87 terminal in the relay connectors, I can turn on the high beams (+plus the filament in the lows) and if I do the same to the horn relay connector, I can make the horn blow. Also, I can hear the high beam relay activate when I pull the trigger (stalk switch) and also the horn relay activates when I push the horn.

Lights are H4 (low) and E1 (high).

So, should I expect that the fuse needs a higher rating and if so, what is an acceptable max fuse size for the high beams?

Thanks
Drew
 

Stevehose

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So your 15 amp blew when you activated the horn by itself? I am running 15 amp fuses in both high and low beam circuits - have you checked all grounds and is there any high resistance/shorts going on in the wires or switches? I suppose you could try a 20 amp fuse but seems to me that if it is blowing at 15 then there wouldn't be enough headroom at 20 and wouldn't want that much draw all the time but I am not an electrician.
 

HB Chris

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Something is wrong if the 15 amp fuse blows. Also, power is terminal 30 and 87 goes to headlights but that doesn't really matter, they can be reversed. Give each relay it's own fuse and see which one blows.
 

afeustel

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Right, 87 goes to the lights so when I connect power directly to the 87 female in the connector, the lights come on.

What is odd is that the relays seem to be triggering just fine from the horn and stalk switch. Also, did not really change anything on the high beam side except to add the fuse.

Low beam wiring got addition of fuse and relay. Is there a way to estimate what current is being drawn by the E1 highs and H4 filament together?

Will go back and check wiring.
 

61porsche

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Total

watts/12 +25%= approximate safe fuse. Don't know which H1s you're running? 500 or 1000?

Are you wiring them parallel? I've also seen them triggered off the negative for the highs.

Horns go bad, horns get wet, horns build up huge resistance best to meter them.
 

afeustel

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Saga resolved

So here is how the investigation went (2 evenings):

Undo everything from the day before (mostly the electrical and friction tape that made my work near the battery look so awesome and tidy). Disconnect all headlights and horns and remove all relays. Remove steering wheel and steering column bottom cover. Access the underdash wiring and drop down some of the harnesses and access backside of fuse box.

Get to work checking all circuits for continuity and shorts. Renew grounds behind headlights.
Install battery and check for voltage at the relay(s) switch wire(s). Check voltage out at the lights with meter and utilize test light to see that all seems to be working.

Install 15 amp fuses and relays and activate relays and check 12V test light at highbeam sockets near lights.

Connect one high beam light and actuate. Fuse OK.
Connect both high beams and actuate. Fuse OK.
Connect both high beams and one low beam (high filament) Fuse blown.
Install 20 amp fuse and try again. Fuse OK.
Connect both high beams and both low beam (high filaments). Fuse blown.
Install 25 amp fuse and try again. Fuse OK.

Hook up horn, horn works, Fuse OK.

Verdict: All wiring checked out fine with no shorts. 15 amp fuse not sufficient to carry load for all high beam filaments (highs and lows). Seems to work just fine with 25 amp fuse.

I think the high beams are just really high watt lights...no kidding, they light up the road like daylight.

Thanks to those who posted with suggestions.

Drew
 

61porsche

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Drew

you should have just said you wanted to go gator hunting and that's what the realys were for!;)
 

afeustel

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With all the rain we have been getting, the road is likely where they will be hanging out!
 

sfdon

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For a little extra info on the '74 wiring diagram- keep in mind that good old Hans and Frans decided to ground the new low beam relay with the high beam filaments. Sounds wacky but it works. White ground wire connects to the fog relay and the high beam relay pin 87. When the high beam is on the the others won't work because they see a positive voltage at the ground side. Seems a little Italian to me.
 

deQuincey

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god knows why I am using this thread to ask questions..., well probably someone else knows why too

the fact is that i would like to understand this rewiring issue a little bit

so i can see that the lowbeam wiring goes straight from the switches in the dash and column to the bulb, without any relay, right ?

steve is adding a relay for the lowbeam, but it is not strictly necessary, and only the addition of the highbeam lights to the lowbeam ones means the need of a relay to support 4 H1 lights electric consum

well, as you probably have guessed, I would like to add two additional lights to my standard setup, but my intention is to use them independently, not necessarily together with the high beam

i will use a relay to operate them and a switch in the lower dashboard to turn them on or off

so, from where do you recommend me to tale the signal (+) ? from the main lights switch in the left side of the dashboard ?
 

Stevehose

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I have both the low beams and driving lights with their own relay to go along with the stock hi beam relay for a total of 3 relays.

I relayed the low beams for safety (no more big amps coming into the dash switch) and as a result they are brighter from the direct to battery connection.

I relayed the driving lights because they were 100 watts each and are activated by the wire from high beam relay and I want them on a separate circuit. That relay is hidden under the light access panel.

In your case it's easy, just run a wire from a fused positive voltage source to the driving light dash switch then on to the relay positive input, and run a fused wire from the battery to the hot input of the relay and the output to the driving lights. Ground the lights to the battery preferably, if not then a good body connection. Ground the other relay connection from the switch input.

The low beam relay is a great mod and highly recommended.
 

deQuincey

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ok, that will be a nice way to go, but i will need a relay support for placing the additional relay for the lowbeams in the relay tray behind the battery

any idea where to find one of those supports ? it seems that they are NLA...
 
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Stevehose

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For the relay socket try coupeking, carl nelson, coupeguy, or Double 02 salvage. Also maybe someone here has one (I got lucky-thanks Hbchris) so try the classified WTB

ok, that will be a nice way to go, but i will need a relay support for placing the additional relay for the lowbeams in the relay tray behind the battery

any idea where to find one of those supports ? it seems that they are NLA...
 

oldcoupe

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Headlight Fuses

Just a comment about fuses:

The one thing you don't want is for lights to go out at speed at night because the fuse rating was marginal, so I used, from memory, 30 or 40 amp fused relays for each of the high and the low sets.

I'd prefer a burning smell from the wiring than my lights going out suddenly, although if the system is wired correctly, what's to go wrong in the normal course of events......?

If something causes a short, like a crash or a dropped spanner, then the fuses will blow anyway.

More than happy to be corrected - this is a safety issue.
 

deQuincey

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I relayed the driving lights because they were 100 watts each and are activated by the wire from high beam relay and I want them on a separate circuit.


now, looking at the diagram i understand this, there is a spare free connection that comes out from the signal of the highbeam relay, see number 15:

conexionluces_zpscc89a5e5.jpg


see detail here:

detailfreeterminal_zpscf532931.jpg


it seems good to use this free available positive signal to activate a relay

the only pity is that you are always joining driving lights with high beams, and thus other combnations are not possible
 

deQuincey

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to install a relay for the lowbeams,

i know, it is a good idea, but how to do it with a limited fuss ?

lets see the diagram, point 14, according to the blue books is a "welded joint"

releparacortaas_zps129711ca.jpg


steve, can you tell me where to find this point ? it will be the perfect place to pick up the positive signal that can feed the new lowbeams relay, but in principle i do not want to dig into the whole lenght of cables, removing the black tape to find it...
 

Stevehose

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Correct, I wanted mine activated by high beams so this works well.

it seems good to use this free available positive signal to activate a relay

the only pity is that you are always joining driving lights with high beams, and thus other combnations are not possible
 

Stevehose

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I am not sure but see if the yellow wire is accessible under the driver side headlight cover plate coming from the harness. It probably goes to that headlight then carries on across to the other, maybe cut it before the first light. I am traveling so I can't see mine till end of week.

steve, can you tell me where to find this point ? it will be the perfect place to pick up the positive signal that can feed the new lowbeams relay, but in principle i do not want to dig into the whole lenght of cables, removing the black tape to find it...
 
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