Strange Headlight/Blower Behavior

Paulporsche · 08:05 AM

Yesterday I drove the car for the first time at night in weeks.

The dashboard lights seemed dimmer than usual and, while the headlights (H4s) were on, they didn't seem to give off much illumination. They were both equally bright but not very very bright at all. Using the flasher stalk switch got the blue high beam indicator to go on but the intensity of the lights didn't increase.

Here's the unusual part: With the ignition off, the fresh air blower in any one of the 3 fan positions, and the light switch on, when I hit the flash switch, I hear a click from near the dashboard blower controls and the fan light at the right of them flashes!

I haven't yet been able to locate a relay for the headlights and I don't see a relay listed for the blower motor yet it sounds like a relay is being activated when I flash the lights. The blower fans work fine when the engine is running. The signals also work fine.

I'm about to check the light wiring and grounding because that often seems to be the cause of low headlights but I'm at a loss to explain why the blower light comes on, and only when the ignition is off. When the engine is running, the stalk activation doesn't seem to do anything to the blower light.

I've also put the battery tender on just in case my battery had run low from lack of use.

Finally, I'm wondering if I have the wiring incorrectly installed at the rear of the lights themselves. I had a similar problem recently with one low light and may have mixed up some wires while working on it...

Anyone have any thoughts on this? Thanks.

Paulporsche · 08:33 AM

Can anyone confirm that this is the correct wiring for the headlights? This is from another car and not mine. Also, I suspect that my problem may be in the passenger's side bucket, rather than the driver's side as shown.

Does anyone have a passenger's side photo they can show me?Or are both sides identical?

timmy2 · timmy2's Garage

If you don't have the headlight relay kit installed on your '77 the problem may lie in the hi/lo switch. All current to the lamps goes through the switch and if the contacts are wearing out they may have developed a high resistance and are lowering the voltage to the lamps, reducing their output.

Mine let the smoke out a few years ago and I had to replace the entire unit and install the relay kit as well as a fuse on the interior light circuit.

There are numerous posts about how to repair them and install the relays to reduce the load on the switch, as well as install the in line fuse.

The relay clicking may just be due to the voltage drop in the circuits due to the high load on the turn signal switch. Could be unrelated as well.

mrdieseldude · 08-08-2014, 11:42 AM

Just so we are all clear, the head lights do not go through the dimmer. Lamp intensity is controlled by voltage. While you may want to lower voltage on the instrument lamps (e.g. to dim them)... you sure don't want to on the head lights. Are you certain system voltage was up to snuff? e.g. about 14 volts with the engine running?

Michael

Paulporsche · 12:14 PM

Thanks Timmy and Michael.

I'm surprised that I can't seem to find a relay, since I've had the H4s (not the same bulbs) in for probably 20 yrs. So I'll continue to look for one.

Glad to hear the headlight power does not go through the dimmer. BTW by dimmer do you mean the dash control for dimming the dash lights rather than the stalk switch? Or do you mean the stalk switch?

As I mentioned, I'm charging the battery now so I'll be able to check later to see if I'm getting 14v. If I am and the lights come back up then it was probably the battery. If I don't have 14 @ the lamp, I'll look into grounds and fuses, wires and connections, since as Timmy said I'm probably getting some parasitic loss through wires etc. I'm thinking the fan uses up quite a bit of power so there may be some reason why it is affected by the possible low voltage, but why when the ignition is off...?

porwolf · 12:40 PM

For comparison, here is a picture of my '79SC Euro H4 headlight wiring for the "parking light":

porwolf · 08-08-2014, 12:39 PM

And here another view of the factory wiring for US models sugar scoops:

mrdieseldude · 08-08-2014, 12:42 PM

By "dimmer" I mean the dash control for dimming the dash lights. Re: bad battery.... might not be that simple. Don't forget about the alternator and regulator; they are all part of the charging system. If any one of the three are bad, you can end up with similar problems.

Michael

Paulporsche · 08-08-2014, 12:54 PM

Thanks Porwolf. I may run a separate ground wire to that terminal you show just to be sure.

Got it, Michael. I'll tackle each in turn. The battery is something like 5 yrs old so, maybe it's simple, but we'll see.

BTW by "relay" I don't mean the round black ones on the fuse block, I mean the aftermarket one installed when people go to H4s. Is it possible that I have the round one, which 911s had through only '77, so therefore I never needed the aftermarket one?

timmy2 · timmy2's Garage

Edited my post, I was not saying the power went through the interior lighting dimmer switch. I was calling the hi/lo switch a headlight dimmer switch. Old terminology from foot switch on floor I guess.
All current to headlights goes through the hi/lo switch in the turn signal controller unless you install relays.

mrdieseldude · 08-08-2014, 02:12 PM

Quote:

Originally Posted by timmy2

Edited my post, I was not saying the power went through the interior lighting dimmer switch. I was calling the hi/lo switch a headlight dimmer switch. Old terminology from foot switch on floor I guess.
All current to headlights goes through the hi/lo switch in the turn signal controller unless you install relays.

I knew that's what you meant... just wanted to make sure everyone else stayed on track

.

Michael

Paulporsche · 08-09-2014, 10:11 AM

More related (?) issues have surfaced. The battery is now fully charged. My hazard flashers do not flash so I am beginning to suspect the relay or the stalk switch.

Is there anyone in the Toronto area who can let me try their flasher/signal relay?

It is part number 914-618-303-11-M504. I can come to you for the trial.

mrdieseldude · 08-09-2014, 03:22 PM

I'm not looking at a drawing, so don't assume I know what I am talking about..., but are you sure your car has a relay for the head lights? If not.., well, that won't be your problem. For a "down and dirty" test, can you bypass the stalk switch? e.g. take it out and use a jumper. Or, with the lights on, you can check the voltage at the back of the stalk switch (which should be the same at the head light... both should be system voltage.) That test should be easier than changing out the part. You still haven't stated what your static voltage is (other than fully charged... but what is that?).

mrdieseldude · 08-09-2014, 03:23 PM

Oh.... forgot to mention... have you checked your grounds? They need to be clean, shiny, and tight.

Paulporsche · 06:49 AM

Thanks again Mike. I didn't read your last 2 posts until after I had done what I describe below.

Apparent success. I first went through the wiring diagrams to see if there is any connection between the emergency flasher, the stalk high/low circuit and the fresh air blower, because I had also noticed that my emerg flashers weren't working. I didn't find anything that would tie the various issues together .

I then went to the garage with my meter to check voltages, but decided to try something else first. My battery tender told me that the battery was now fully charged, and the dash lights looked fine so I took the leap of faith and checked the stalk light switch to make sure that the interior connections were good. I could get a pretty good look at this through the side of the cover, without removing the steering wheel. I had done the bending fix that was posted here a few months ago and everything seemed in order.

Opening up the light buckets I noticed that the only lights lit were the smaller parking lights. I took one halogen bulb out and found that there was quite a bit of corrosion on the ground connection, so I sanded it down and reinserted but still had no illumination. The white wire connector is long gone so I just have spade connectors. I then replaced the bulb with the lower wattage one I originally had, and the bulb worked fine, both on the high and low settings.

I then checked the other bulb, which was still unlit, and found much cleaner connections so I again replaced the bulb with the older one, and I now had 2 working lights.

Right now it seems that the unlikely coincidence of both bulbs being shot at the same time has occurred. They are 7 yrs old. I'm going to hook up a 12v source to both bulbs now that they are out of the car and see what happens. If they don't work then I'll just get some replacements. If they do then I'll have to go back to the car for further investigation. Maybe I do have a relay after all, or perhaps I'm getting some voltage loss that prevents the higher bulbs from illuminating.

Regarding the clicking noise and the illumination of the fan light when the ignition is in start mode I'm thinking this has to do with the fact that during start usually various systems in the car are shut down to enable the engine to start. I'm going to pursue this further. For example, if there is a relay for the blower, did whoever installed the H4s use that relay as a headlight relay? I'm thinking that may be a possibility.

Concerning my flashers not working, I'm trying to source another working flasher/signal relay to try and see if that cures it. Since the turn signals work and the lights illuminate when the flasher switch is pushed I'm thinking it's the relay.

Paulporsche · 02:40 PM

I decided to check my battery output. Engine off: 12.77v. Running:14.26v. Battery seems fine.

I then checked the resistance between the pins of the lamps: .4ohm on all 4 combinations. I was surprised it was not infinity or zero.

I then hooked up a 12v power source to the white (+) and brown (-) pins of each of the 2 lamps, and then between the yellow and brown pins and got no illumination from either bulb.

I should check the voltage @ the connections in the buckets but I think I'll wait until I get new higher wattage lamps, and remake that one corroded wire and connector.