Driving light wiring help

[RGHarvey]

I would appreciate help. I have installed the Russ Thompson turn signal using the schematic from MK4build site (Russ Thompson Turn Signal [FFR Roadster]) in my Mk4 roadster build, assigning the stalk button to toggle the high/low beams [I am using the Ron Francis harness]. I want to add driving lights, with a wrinkle. I want to use a 3 position toggle switch on the dash:

Position 1: driving lights on – with high beams only (i.e., driving lights turn off when I hit button to go to low beams and back on when I hit button for high beams again)
Position 2: driving lights off
Position 3: driving lights on – with low beams Sort of fog lights - yes, I know that the fog light pattern is different from the driving light pattern; just trying to use what I have. I don’t have any preference as to whether or not the driving lights stay on with switch to high beams, but I assume they would not stay on.

I would like the driving lights to be on a separate circuit/fuse from the headlights. I have added a hot lead from the driving lights to the front harness (runs to dash) and a separate ground for the driving lights. I have also isolated a switched hot lead from the Ron Francis fuse panel to use for power.

My problem: how do I interconnect the button switch on the stalk of the RT turn signal and the hot lead to the wiring for turn signal set-up to accomplish my goal?

Thanks for advice.

[Bob Gruen]

You'll need a relay for the driving lights.

Take the high beam + to the terminal that corresponds to 'On' for the three position switch.

Take the low beam + to the terminal that corresponds to 'On' for the three position switch.

Take the 'common' terminal of the three position switch to one side of the coil of the relay. Ground the coil on the other side of the relay. The relay's contacts should now be able to control the lights.

It is a VERY good idea to run a relay for each of the light pairs, running heavy gauge wire directly from the battery, through an inline fuse, and to the lamp terminals. You can read up on this at Stern lighting. I did this with the terrible lighting on an older 911 and it worked wonders for only $50.

Bob

[RGHarvey]

Thanks for the help. I'll add a relay to the circuit. I'm still not sure how to control both the high beams and the driving lights using the button on the stalk.

Bob

[Big Blocker]

" My problem: how do I interconnect the button switch on the stalk of the RT turn signal and the hot lead to the wiring for turn signal set-up to accomplish my goal? "

Using Bob's above description for adding a relay, when you press the Russ Thompson TS button to toggle between High and Low beams, you effectively toggle the VW "switching" relay to energize either the High or Low circuit . . . since it's tied to the power going to the High or Low bulbs, it will pull in the relay to your "Driving lights" if the toggle switch is in position 1 or 3 in your description of how you want it to work. Position 2 will act as an off switch for your Driving lights.

The Driving light will go out when you switch from High to Low or Low to High, depending on your toggle switch position selection:
Position 1 = High beam and Driving lights (will go out when switching to Low).
Position 2 = Switch between High and Low, NO Driving light available.
Position 3 = Low beam and Driving lights (will go out when switching to High).

HTH

Doc

[Thumper135]

If I’m following this correctly, you want to have a toggle switch on the dash that runs the driving lights and have it get its power in conjunction with the RT High / Low beam button on the stalk? I’m guessing this is so you can have the driving lights ON in (let’s say) the High Beam setting and have them go off when you have to go back to the Low side without having to manually turn them off with the switch, and then have them available in the LOW setting as well. If this is where you are going with this, you will definitely want a relay to keep things in check and I can get you a diagram this afternoon if you want one.
PM me if you want a drawing of this.
J.D.

[OSU Cowboy]

Bob - thanks for the Stern Lighting link ... that information helped me a lot in terms of integrating relays into the Ron Francis harness.

David

[AC Bill]

Curious..why do you even want your driving lights turned on, when running the low beams? Is it just for the look?

You certainly won't win any friends driving at night with that combo. For some reason I see a lot of fancy pick up trucks doing that, and the driving lights are still bright enough to be offensive. Not dissimilar to having the hi-beams turned on.

[Frank Messina]

Originally Posted by AC Bill

Curious..why do you even want your driving lights turned on, when running the low beams? Is it just for the look?

You certainly won't win any friends driving at night with that combo. For some reason I see a lot of fancy pick up trucks doing that, and the driving lights are still bright enough to be offensive. Not dissimilar to having the hi-beams turned on.

Good point Bill. You frequently see people around here driving in town with every light blazing away. Very un-cool and annoying to other drivers.

Frank

[Big Blocker]

from Bob Gruen's description above . . .



Doc

[rich grsc]

Originally Posted by AC Bill

Curious..why do you even want your driving lights turned on, when running the low beams? Is it just for the look?

You certainly won't win any friends driving at night with that combo. For some reason I see a lot of fancy pick up trucks doing that, and the driving lights are still bright enough to be offensive. Not dissimilar to having the hi-beams turned on.

If you read the post, he would like the option of using them as fog lights. They most likely won't work well as they have the wrong pattern and color.

[RGHarvey]

Rich,

You're right (as is Thumper). I know the pattern is wrong, but thought it might be better than nothing; I've read that color doesn't really have much of an impact on visibility. I'd use this option when traffic permits; that's part of the reason for switch position 2.

Doc, and others, thanks for all the help. Looking at Doc's diagram, am I correct that the headlights and driving lights are still on the same circuit (fuse)? If so, how do I separate them? I have identified a separate circuit that I could use for the driving lights. My thought is that I'd like to have redundancy (i.e., headlights or driving lights, if the other fails). Haven't calculated load of 4 lights (I need to do this). Maybe this is going one yard too far? (Suspenders and 2 belts)

Bob

PS After looking at the diagram for awhile, can I just send the lead from relay position 30 to new power source?

[mn2deep]

Originally Posted by RGHarvey

My thought is that I'd like to have redundancy (i.e., headlights or driving lights, if the other fails). Haven't calculated load of 4 lights (I need to do this). Maybe this is going one yard too far? (Suspenders and 2 belts)

Bob

PS After looking at the diagram for awhile, can I just send the lead from relay position 30 to new power source?

I'm not following the new powersource question, but I can tell you, if you lose power to the hi or low beams, you will then, not be able to trigger the relay to power the driving lights. The power to your headlights is being used to trigger the relay.

[d42davis]

The headlight switch has it's own internal circuit breaker - no fuse. It's a thermal device which can auto-reset when it cools.
Your new circuit needs to have a fuse between terminal 30 and the 12 volt source.
As RGH said, your relay is activated by the headlights. If they aren't working, your relay has no power to activate.

[Thumper135]

Here are the two I have on file, I’m sorry it took a couple of days to get to them. The one is almost identical to Docs with the five post relay. The other uses two four post relays, but does the same thing.

[Thumper135]

RG, I took a good look at these (a friend did them for me) and it looks to me like the single relay would be the way to go on this. The other does the same thing, but I can’t see any reason to run the two relays. It just looks like a lot of extra wiring to me. Sorry about that, I decided not to use driving lights on mine, so I never really looked at the differences in these. Personally, I would use the single set up like Doc posted as well.
Good luck with the build.
J.D.

[RGHarvey]

I think I've got it! Thanks again for all the help. As a new builder, I really appreciate the advice!

Bob

[RGHarvey]

Hi Doc,

Since our last exchange of messages, I have found a driving light that has an integrated fog light as well. So, I need to modify the wiring diagram you were kind enough to send me. I haven't worked with relays before this project, but have tried to read up and understand your diagram. I've attached my attempt to revise the wiring - same goal in mind for the switch (which I subsequently added to my dash - almost permanently). Not as good with the drawing of wiring diagrams.

The way I see it, the center position of the switch sees current only when the lights are on, and then from only one source (hi or lo beam); then connecting the other switch poles to the relays would effectively isolate the driving and fog lights on separate circuits. I'm not sure if I have caused any problem attaching hi and lo beam leads together on switch position 2. If I understand the operation of the relay correctly, feeding power back to the VW relay shouldn't be a problem because it's going to an open position.

Do you see any problems with this arrangement?

Many thanks,
Bob

[d42davis]

" I'm not sure if I have caused any problem attaching hi and lo beam leads together on switch position 2."

Yes a problem. As shown, your Hi and Low beams will always be on at the same time regardless of Hi/Low switch position. This can be fixed by adding a diode between Low and terminal 2 , and between Hi and terminal 2.

[Big Blocker]

the toggle switch will be your isolation for either "Driving" or "Fog". The way I see it, you are applying power to the VW switch from your headlight switch.
The headlight switch applies power to [both] HI and LO terminals of the VW switch. True, only one set of contacts are closed, allowing power thru the VW switch, but your Hi and LO wiring is tied together at the terminal.

I'd follow d42davis' advise and add the diodes. Make sure the diodes are sized accordingly for the amperage draw of the lamps, your drawing does not reflect a relay controlling them so full power is traveling thru your switches.

Running power to an "open" set of contacts will work, just not the way you've drawn it here, that's how I've wired my turn signal circuit so I can get both upper and lower rear lights to come on for both brake or TS. Living in Vegas, I wanted as much light showing as possible in our bright sun.

I'm assuming that you are using the RT stalk button to trigger the VW relay.


Relay 101
Think of a relay as a toggle switch, controlled by electricity instead of your finger. The 86 contact is your "electrical finger" (85 being grounded). When you apply power to 86, you are toggling the switch from off to on.
The other terminals of a relay are for controlling your device. Fused power is always available on 30. When you "electrically finger" the relay on, power from 30 is applied to 87, effectively turning on your relay controlled device.
The difference/advantage is: your activating switch doesn't have to handle the high current loads of your device.
Think of a simple Fan circuit: (Scenario 1) fused power to switch to fan to ground (20 amp draw travelling thru your switch. (Scenario 2) fused power to a remotely mounted relay (very close to the fan for optimal voltage availability) relay terminal 87 connected to fan, fan grounded. Activate relay with a 200Ma circuit, fan comes on, switch only sees 200Ma, not 20 amps. Fan gets full voltage instead of a lower voltage due to line and switch resistance.

Doc

[RGHarvey]

Many thanks to d42davis and Big Blocker! The cloud just lifted - I see now how the connection at the open switch would result in powering up both hi and lo beams. I'll add the diodes for isolation. I think 3 amp diodes should do the trick. Yes I'm using RT's turn signal set-up.

Bob

[Big Blocker]

Bob,

Since your diodes are going to be on the load side of the circuit, I'd check the amperage draw before buying 3 amp diodes . . . headlights(2) (on HI) normaly draw approximately 10 amps.

Doc

[d42davis]

The diodes are only providing power to operate the relays. The relays will draw less than an amp.
DD

[RGHarvey]

As I thought about the problem, I was leaning toward Doc's solution. Even though the feed is to the relay ultimately, the connection of hi and lo beam feeds at pin 2 of the toggle occurs prior to the relays, hence it would seem that the full headlight current could flow back to the VW relay. Hence, I think I should use a diode that is the same amperage as the fuse for the headlight circuit (i.e. 15 amp).

[Big Blocker]

d42davis is correct, the diodes will only be providing directional control to the relays that control the driving /fog lamps . . . lower amperage, smaller type diodes will be enough, no need for 15 amp ones.

Doc

[RGHarvey]

However, isn't the flow I'm trying to restrict the full headlight power that is being fed through the VW relay? I'm missing something. The full headlight power goes from the headlight switch, through the VW relay, then to the headlights, correct? If so, then that is the same power that could flow back from terminal 2 of the toggle switch to terminals 56A or 56B of the VW relay, isn't it?

Bob

[Big Blocker]

of the VW relay, where you are "taping into" the power to drive the relays, you are only drawing the power that the relays require . . . about 200 - 300ma. A 1 amp diode would be more then enough. Full power is going to your headlights, partial power is going to the toggle switch. If the toggle switch is in the OFF position, there is no draw. If the toggle is in either of the two positions for Fog or Driving, the draw is what the relay draws . . . Fog and Driving are getting their power from a dedicated source, as are the headlights.

Doc

[RGHarvey]

OK, I think I'm close to getting it. But, if the switch is in the 2 position, why isn't there the full flow back to the VW relay? I'm using the wiring from Mk4build site (diagram attached). Looks like the terminals 56 A&B feed directly to the hi and lo beams, so would be at full current of headlight draw wouldn't they?

[d42davis]

You need to reverse terminals 86 and 87 on the relay. 85 is coil ground. 87 is coil power from the switch. 30 connects to the 12 volt source for the dr/fog lights. 86 provides that power to the dr/fog lights when the coil is energized.

[RGHarvey]

D42davis, thanks. However, the diagram on my relays (PN 961-1A-12DM) shows terminals 85 and 86 controlling the coil, and terminals 30 and 87 as the switched circuit. Maybe it's different with other relays.

Still don't get why I'm not getting full lighting load at terminals 56 A or B when opposite terminal (56 B or A) is energized. Hence, need for larger diodes.

[d42davis]

OK I thought the relay terminal arrangements were pretty standard. As long as you coil is attached to ground and the switch terminal 1 or 3, you should be OK.
Remember that the power for the headlights is coming from the dashboard headlight switch (thru the VW relay,) not thru your dr/fog switch and relay. Power for your dr/fog lights is coming from the 12 v bus and should be fused. Power for the relay coils is coming from the headlight circuit, but is much less than an amp.