driving with lights on during the day

[Robert Thiemrodt]

Jim
Just replace your H4 bulbs with leds. See one of my posts about where to get them.

Without doing a bunch of searching, where do you get the led's from?

I also seem to have one light (drivers side) that at times puts off more of a glow, than a normal light. Upon revving it seems to wake it up, but then it seems to go dim erratically. I cleaned all wiring, including to ground, but to no avail.

I think the source Mark Roth was referring to is Classic Dynamo & Regulator Conversions, Ltd. They do sell a £ 60 six volt H4 replacement which has the little surface mount LEDs in about the same place as the filaments in an H4 bulb.

Regarding your dim driver's side head light:

Clearly, you have a voltage drop somewhere; it only takes 0.13 Ω to cost you one volt. The battery should give 6 volts, the generator at speed will bring it to about 7 volts.

It could be a dirty connector, a loose connector, or even bad wire although I suspect bad wire wouldn't be intermittent (and it's less likely than a bad connector).

People always say "clean the grounds" but a voltage drop on the positive side of the headlight will look just the same. However, if it affects both high and low beams it pretty much has to be the ground side--the positive side wiring's separate for the two beams. Unless, maybe it's something funny with the bulb.

Have you checked the fuses? On a 356A at least the drivers side high beam is fuse # 10 and low beam is # 11. Are the fuses held in tightly? I think you may be able to bend the tabs holding the fuses a bit. Are the fuses clean?

Turned on lights earlier today. Drivers side still dimmer, and at times still not illuminating at all. When I turn on high beams, they are both equal at 100%. I did feel the fuses with lights on low beam, engine off. Fuses 9 and 10 are too hot to keep your finger on them. My 9 and 10 fuses are white (8amps) my online research shows these should be 25 amps, is this correct? I certainly don't want to risk electrical fire. Help??????? David?????

[Phil Planck]

Am not able to drive my 356 yet as its only been 18 years into resurrection, but drive my 912 always with lights on.

[Jim Alton]

...

Regarding your dim driver's side head light:

Clearly, you have a voltage drop somewhere; it only takes 0.13 Ω to cost you one volt. The battery should give 6 volts, the generator at speed will bring it to about 7 volts.

It could be a dirty connector, a loose connector, or even bad wire although I suspect bad wire wouldn't be intermittent (and it's less likely than a bad connector).

People always say "clean the grounds" but a voltage drop on the positive side of the headlight will look just the same. However, if it affects both high and low beams it pretty much has to be the ground side--the positive side wiring's separate for the two beams. Unless, maybe it's something funny with the bulb.

Have you checked the fuses? On a 356A at least the drivers side high beam is fuse # 10 and low beam is # 11. Are the fuses held in tightly? I think you may be able to bend the tabs holding the fuses a bit. Are the fuses clean?

Turned on lights earlier today. Drivers side still dimmer, and at times still not illuminating at all. When I turn on high beams, they are both equal at 100%. I did feel the fuses with lights on low beam, engine off. Fuses 9 and 10 are too hot to keep your finger on them. My 9 and 10 fuses are white (8 amps) my online research shows these should be 25 amps, is this correct? I certainly don't want to risk electrical fire. Help??????? David?????

If your high beam's fine and the low beam's dim or intermittent then the problem can't be the ground (ground's common to both high & low beams)--it has to be somewhere between the fuses (where the right and left circuits separate) and the headlight.

The '64 reprint of my 356A driver's manual says fuses 12, 11, 10, and 9 should be 25/40 amp (blue). The very small cross section in the white (8/15 amp) will increase resistance and might explain them being hot.

The low beams will draw somewhere between 7.15 and 9.15 amps depending upon your bulb so the nominal 8 amp fuses are definitely marginal. You need the red fuse (~ 15 amps) as a minimum.

I wouldn't worry much about losing protection with a higher-amperage fuse: the big danger in the headlight circuit is a true short circuit (straight to ground) and a true short will draw enough current (theoretically infinite) that a 15 or 25 amp fuse will blow.

Changing the fuses will also give you clean mating surfaces on the new fuses. Those are a candidate for the root cause of the dim headlight.

So, I'd suggest:

• Check the wire clamps in the fuse box--aren't they screw clamps?
• Clean the wire ends (Würth Contact OL is real good) at the fuse box
• Clean the tabs that hold the fuses, make sure they contact the fuse firmly
• Check the connector at the headlight could it be loose or dirty (Würth Contact OL)?

I don't think a 356 has any in-line wire connectors between the fuse box and the headlight (unlike early 911s) but I haven't tried to trace the wires all the way.

By the way, when I installed H4s in my 356A, I hid two 6 volt fused relays in each headlight bucket with power coming directly from the battery. That protects the old headlight switch and headlight flasher relay and it also ensures power to the headlights. I don't have the powers of communication to describe that in detail but such an approach would probably cure your dim headlight.

[Jim Neil]

I think it's a good idea. Bought a new Harley a couple years ago, don't ride it much, but scratched a long time itch. I like the fact that if the ignition is on, the lights are on (cannot turn them off). Changed the taillight and front and rear signal lights to brighter LED, have a rack with a second built in LED taillight, and just got LED replacements bulbs for the headlight and two front driving lights. I like to do everything possible to be seen!

On the 356, I have only done H4's and Leoni relay, and the culayer taillights.

[Robert Thiemrodt]

Jim,
Thanks for all the advice. When I bought the car it came with a factory workshop manual. I dug it out and took a fuse box picture of 7-12. It is showing 9-12 as being headlights as you mentioned, however it is showing them as 8 amps. Did they just undersize the fuse back in the day? My workshop manual is for 356a 1300-1600 super. On another note, I bought a repop owners manual, and it shows 25 amp as you state. Please see picture. I'll switch to 25 amp and see how it plays out.Thanks again

[Jim Alton]

I don't think you've identified your 356 (pre-A, A, B or C) in this thread so I've been kind of guessing and using my '58 356A as an example. I honestly don't know if the fuse sizes in my '64 reprint of my 356A driver's manual are the same as in the '57 edition.

356 Headlight Evolution

The earliest 356 (pre-A and probably A) non-sealed beam headlights used a BA-20 bulb which I believe was 35 watts/35 watts. That's 5.8 amps at 6 volts so an 8 watt fuse would be adequate.

Later 356s (probably Bs and Cs) used a P45t bulb which was 45 watts/40 watts. That's 6⅔ amps low beam and 7½ amps high beam which is pushing it for an 8 amp fuse.

The sealed beam 6 volt headlights today are 50 watts/50 watts, drawing 8⅓ amps at 6 volts--too much for an 8 amp fuse.

6 volt H4 bulbs draw 55 watts/60 watts (9.2 amps/10 amps) so if these don't blow 8 amp fuses there's a problem.

Recommendation

Change fuses. Even putting in new 8 amp fuses could solve your intermittent headlight problem if it's a dirty or worn contact surface on the fuse. But, a bigger fuse could help--even a 25 amp fuse will protect you from a short circuit.

Install relays. The big advantage of relays is that they'll protect your 50+ year old switches and flasher relays.

If you take the approach I did--hiding the relays in the headlight buckets--you'll bypass most of the potential bad connections that are causing your problem now. Of course if the problem gets really bad you mightn't have enough power to close a relay.

[Robert Thiemrodt]

Jim,
Sorry about that, 58 356a. I'll start with the cleaning and larger fuses. Where are you getting the relays, and, are they just being spliced in line? Thanks for your help.

[Jim Alton]

I'm not certain where I got the relays (it was over ten years ago) but I used these: sierramadrecollection.com/Fog-Light-Relay-6-Volt-25A-Sicherung-p19621.html.

I fished 8 gauge wire from the battery positive terminal through the conduits from the trunk to the headlight buckets to power the relays.

Instead of going to the headlight bulb, the yellow and white wires go to separate relays and power out from the relay goes to the headlight bulb.

It's necessary to wire each relay to ground, too. Also, since the relays aren't fastened down all the relay terminals (except ground) have to be insulated lest they touch ground.

I really should take some photos and write something up for the registry.

-------------------

I used relays with fuses--an alternative would be to use inline fuses in the power wire from the battery, preferably close to the battery.

[Robert Thiemrodt]

Jim,
Appreciate the directions. I'll start with cleaning and larger fuse size tonight and see what happens. It's 50 degrees in Indiana, this is driving weather!!

[Robert Thiemrodt]

Jim,
Mission accomplished. Tightened down screws 9 and 10. Fuse 9 screw was loose by about 3 full turns. Fuse 10 barely anything. After tightening, the drivers side light came on full force. So I assume on the picture I sent you, left (links) refers to the drivers side headlight?

[Jim Alton]

Jim,
Mission accomplished. Tightened down screws 9 and 10. Fuse 9 screw was loose by about 3 full turns. Fuse 10 barely anything. After tightening, the drivers side light came on full force. So I assume on the picture I sent you, left (links) refers to the drivers side headlight?

Yes, I would assume the labels in the fuse box would be for the far more common left-side drive cars.

By the way, I generated a schematic of my relay setup (with Greg Bryan's headlight diagram).

[Robert Thiemrodt]

Jim,
Mission accomplished. Tightened down screws 9 and 10. Fuse 9 screw was loose by about 3 full turns. Fuse 10 barely anything. After tightening, the drivers side light came on full force. So I assume on the picture I sent you, left (links) refers to the drivers side headlight?

Yes, I would assume the labels in the fuse box would be for the far more common left-side drive cars.

By the way, I generated a schematic of my relay setup (with Greg Bryan's headlight diagram).

Relays.jpg

Thanks for schematic, and all your help Jim. Nice to have both lights on, without dimming of drivers side.

[Bill Oldham]

I dug out my old post about wiring mod to drive with lights on and have updated it. (I always drive with lights on; anything to reduce chance of getting hit is worth it.(

First of all, unless you use LED lights, DO install headlight relay. Bill Block sells the Leoni relay which installs very simply. Its well thought out and does not degrade from originality, plus your switches will thank you.

Because of electrical wear on switches, I do not recommend this improvement unless you have either installed headlight relays or installed LED headlights. But if you have, this is a VERY simple change to wiring so that your lights go off when you take the keys out. No dead batteries and no buzzers. I do not know about the wiring on T2 and earlier cars, but for all B's and C's this works. The only complication is that cars with left hand ignition switch are slightly different than the right-hand ignition switch (like my 60 T5 Roadster). What follows is a description of the change to make and two electrical diagrams (before and after the change)

Here is what you do:
A: (For a Roadster or any T5-6 with ignition switch on the right side of steering wheel)
1) disconnect battery for safety
2) the ignition switch has 3 terminals on one side labeled "30" (see diagram). One thick red wire (coming from the light switch, albeit indirectly, thru the harness) is the only thing plugged in there originally. There may be more accessories now, because this is a 6 (or 12)V always-hot supply. Unplug this wire and plug it instead to the opposite side, terminal 54 (the accessories, or radio side) There are 3 holes here, see diagram. If you do not have a radio they are probably all vacant. You can see if you moved the right wire because if you reconnect the battery, the only live 6v (or12) on the back of the ignition switch is now moved to terminals 54. (but disconnect the battery again).
3) Now you have to move one more wire:
there are 3 wires connected to the 3 terminals "30" of the light switch (red wires). One of them goes to the signal dimmer switch (i.e. to the steering wheel switch), one of them goes to the ignition switch (in fact it is the other end of the wire you just moved in step 2). The third wire into terminals "30" on the light switch is a red wire going to the top of fuse 2 (or 3 or 4) which in tern goes directly to the battery.
Unplug this wire from the light switch, and plug it into the empty spot (terminal 30) you created on the ignition switch in step 2. To be sure its the right wire, reconnect the battery and see if terminal 30 on the ignition switch is always hot, whereas terminal 30 on the light switch is hot only when the ignition is on auxiliary or run.

B :If you have a “left hand” ignition switch then its slightly more complicated.
The diagram is exactly the same, but the red wire will not reach over to the ignition switch, because it comes out of the harness close to the light switch to the right of the steering wheel. So you just make a two foot extension wire, one end female, one end male (with insulator protecting the female end) and plug the male end into terminal 30 of the ignition switch and the female end over the harness wire formerly plugged into the terminal 30 of the light switch. The little blue blip on the "after" diagram represents the connection of the extension wire to the red wiring harness wire.

Thats it ... an easily reversible modification that will keep you from draining your battery by leaving your lights on. Note that if you WANT to sit motor off with your lights on, then you still can. Simply turn the ignition switch to the left (I guess this is the "radio" position). But if you take the key out of the ignition switch, the lights are off.

You should document this and all changes neatly on a paper you keep with the car papers so future owners have a chance to figure out what you did. I suspect that Porsche chose not to wire this way simply because they did not want the headlight current going through the ignition switch (which they already had compromised by running the starter solenoid current through).