headlight help, part 2

[Rtrorkt]

A couple of questions for the brain trust.

Left headlight quit working. Right is fine. Am I correct in the idea that fuses 10and 12 are left side low and high beam? Have put a new set of H4's in. The left side worked for 60 miles then quit.

If not the fuse, then any suggestions would be welcome

Second, the guy that designed the little spring holders for the lights should be shot

[Rtrorkt]

I am thinking the fuses are fine. Does the three prong connector go bad? How could I tell?

[pete3799]

Give the fuses another check. When i was getting ready to get an inspection sticker last year my driver side was out. Pulling the fuse out and cleaned the terminals was the fix.

[Rtrorkt]

Thank you. Have done the fuses and made sure the fuse block connections are tight. Have no continuity across the connector which I suppose suggests a break in the wire somewhere.

Had new H4's put in and took out a set of HID. Should be less power draw I am thinking. Anyway, driving to Carmel in August the left light just quick. Looked the fuses then and they looked ok. Been sitting in my garage while I try to sort this.

I hate electrical issues.

I can see the wire comes from the bucket through the body, then is wrapped with other wires that disappear into a back grommet that goes back into the fender. I suppose I can run wires from the correct fuse directly to the connection and see if that works. Again, I am assuming 10 and 12 on the fuse block, which in my car are two blocks. I have counted from the top. 7.5A fuses.

[Walter_Middie]

Rtrorkt,

I assume you are working on the 1969 912 in your signature.

Yes, you have 2 fuse blocks. The 10th fuse is RH High beam (blue wire?) and fuse #12 is RH low beam (Yellow wire?). The colors blue and yellow are used on my 1975 911, yours may be the same.

If both your high and low beam do not work - they have separate +12V wires - the problem may be something common to both high and low beam like the ground wire.

I'd run a separate ground wire from a battery or known good ground, directly to the headlight connector and see if they both work. If they do work - then you need to find where the ground wire is not making good contact.

[rothaus]

Not sure what year 911 you got, however, look for the yellow wire for the low beam and white wire for the high beam. There must be one wire each coming from the switch and 2 on the other side of the fuse going to the headlights. Yo can check with the voltmeter if you have 12V on both sides of the fuse. If you have 12V after both fuses, the issue must be further down in the wiring going to the headlight.

Image here from another post of an early 911


Hope this helps.

Cheers
Engelbert

[Rtrorkt]

Originally Posted by rothaus

Not sure what year 911 you got, however, look for the yellow wire for the low beam and white wire for the high beam. There must be one wire each coming from the switch and 2 on the other side of the fuse going to the headlights. Yo can check with the voltmeter if you have 12V on both sides of the fuse. If you have 12V after both fuses, the issue must be further down in the wiring going to the headlight.

Image here from another post of an early 911


Hope this helps.

Cheers
Engelbert

Thank you. I have not figured out how to add an arrow to pictures posted, so I will try to describe my question. Upper left of your pic is where the wires from the lights come through the fender from the light bucket. Upper center is where the wire loom goes back into the fender. Is that a connector there? Or just a grommet? Looked at a video showing a wiring loom and it looked like this is a connector. Will be looking further into wiring today.

[rothaus]

Originally Posted by Rtrorkt

Thank you. I have not figured out how to add an arrow to pictures posted, so I will try to describe my question. Upper left of your pic is where the wires from the lights come through the fender from the light bucket. Upper center is where the wire loom goes back into the fender. Is that a connector there? Or just a grommet? Looked at a video showing a wiring loom and it looked like this is a connector. Will be looking further into wiring today.

See the arrow, that a plug and can be unplugged. You can check if you got 12V there and also if you have continuity from the plug to the headlight.

[Rtrorkt]

not that anyone really cares, but I finally got my multi-meter to work properly. Discovered that fuses that looked good were bad. Go figure. Now I just need to find out why they blew.

[PeteKz]

NOTE TO ALL: After many heat cycles the thin metal strips on the fuses crack. They may look good to the eye, but are not making contact, or are contacting intermittently. It's just a poor design, but what all German cars used back then, and which Porsche carried forward after other makes went to newer fuses.

Bottom line: One of my former friends over on a Mercedes mailing list came up with a plan. Change your fuses at least every 10 years. And if you're having any strange electrical problems, try swapping the fuses first.

[Rtrorkt]

Thank you. Working with an expert we determined that somehow there is a ground in the headlight bucket with one of the wires grounding there. Have changed my fuse box to the blade type. The blown fuse was hard to see without my multi meter.

[David Inc.]

Originally Posted by PeteKz

NOTE TO ALL: After many heat cycles the thin metal strips on the fuses crack. They may look good to the eye, but are not making contact, or are contacting intermittently. It's just a poor design, but what all German cars used back then, and which Porsche carried forward after other makes went to newer fuses.

Bottom line: One of my former friends over on a Mercedes mailing list came up with a plan. Change your fuses at least every 10 years. And if you're having any strange electrical problems, try swapping the fuses first.

Yep. My power windows failed one day with a fuse that looked absolutely perfect. I swapped the fuse as a test and they went right back to normal.