Electrical issues

[mybd911]

Could anyone help me locate the horn and high beam bypass relays in a 1968 - 912 chassis. I am experiencing low voltage (6.5V) to my low beam.
Thanks Merle

[911pcars]

Originally Posted by mybd911

Could anyone help me locate the horn and high beam bypass relays in a 1968 - 912 chassis. I am experiencing low voltage (6.5V) to my low beam.
Thanks Merle

There's a horn relay in the circuit. If the circuit is okay (even if the horn is malfunctioning), you should hear the relay "click" as it makes contact. The relay is typically in the area behind the instruments.

All source voltage for the headlamps is controlled by the headlight switch behind the steering wheel. 6.5 volts at the low beams indicates a voltage drop in the system, typically a bad ground wire, dirty/loose connection. If both headlights are equally affected, that usually indicates an issue further upstream (e.g. the headlight switch or even the circuit fuse).

Probe the source wire at the headlight with a voltmeter at convenient breakout locations (harness connector, switch, etc.) until you find where the source voltage is normal (12+ volts). The excessive resistance creating the voltage drop will be between that location and the load/load ground.

Sherwood

[mybd911]

Thanks Sherwood. Their are two relays in front of the clutch and brake pedals do you know what they are for.
Thanks Merle

[911pcars]

Originally Posted by mybd911

Thanks Sherwood. Their are two relays in front of the clutch and brake pedals do you know what they are for.
Thanks Merle

I've got a 69 911, but not sure the electrical layout is the same. Can you post a photo for the forum to see?

Sherwood

[mybd911]

You will have to excuse me for my lack of technical awareness, but I do not know how to attach a picture. I will have to have my grand children teach me the ropes.
Thanks Merle

[911pcars]

Originally Posted by mybd911

You will have to excuse me for my lack of technical awareness, but I do not know how to attach a picture. I will have to have my grand children teach me the ropes.
Thanks Merle

Wayne has to have a basic tutorial somewhere on uploading photos. My elementary steps:

With a dig. camera and your computer:
1) Take a digital photo
2) Upload the file(s) into a file folder in your computer
3) With appropriate imaging software, convert to 72 dpi. Resize to a pixel width of approx. 700-900 pixels. Record the file name and location (file folder or equiv.) for reference for below

This image is 800 pixels wide:


On a thread such as this:
3) Mouse over and click on Click here to Upload a Photo. It's below this text window
4) A Pelican Parts window will pop up on your monitor.
5) Click "Browse" to locate and select the photo you want to upload from your computer to the PP forum servers. The selected file name will appear next to the Browse window.
6) Click on "Upload Now". An image code identifying your file will be inserted into this text window. After selecting "Submit Reply" or "Preview Post", the image will appear at the end of your text. If needed, you can move the image code anywhere within the text box before selecting "Submit Reply". You can also edit a previously submitted reply, but that's another lesson.

Hope this helps.
Sherwood

[mybd911]

Thanks Sherwood. Here goes I have no idea weather this will work.

[donporfi]

Check for corrosion on the connectors, fuse boards, grounds.

[911pcars]

Well done Merle. A wiring diagram will help you ID the relays via the wire color codes:
PorscheWiringDiagrams

Locate the horn, then follow the current path back to the horn button and the fuse box via the relay and in-between harnesses.

Sherwood

[mybd911]

Thanks to all for your input. I have been tracing and investigating my issue for the last few days. You will not believe what I found for the high low beam problem. Someone inadvertently installed the connector to the right hand headlight upside down.
In my investigation of relays and their locations; the one shown on the left of my picture is actually the bypass relay for the high beam signal (#43). The relay on the right is the warning signal relay (#46). The horn relay (#42) is located in front of the battery. A lead had disconnected and thus the horn problem solved.
Thanks to all Merle