Headlight Switch question

[gregg hake]

In my restoration, I am trying to get the headlights (LED) to turn on. I am having zero luck.

In the schematic, I have voltage at the input (terminal 30), and when I pull out the knob 1/2 way, I see 6 V at terminal 57 (feeds the relay). When I pull the knob out all the way, (and Lights should come on) I see no voltage on 57...and obviously no clicking on the relay.

As a test, I manually apply voltage to the relay (using 57) and there is clicking, so I assume the relay is OK.

Am I supposed to see zero volts on terminal 57 on the light switch when it is pulled out all the way?

[Brad Ripley]

You need Joe's book, see page 6, "Driving - Parking & Flashed Lights". Answer to your question is, Yes.

[David Jones]

Greg, the question on LED headlights not turning on has come up before. I would suggest you check the input voltage polarity to the light source. LED's MUST have the polarity correct unlike "normal" light bulbs. Just to be sure, use a jumper from the battery +ve to the LED and be sure the correct lead is grounded and see if the LED turns on, then make sure the polarity of the incoming power is correct for that LED light. Note that the relay clicking only means the relay is working and as that is not polarity sensitive it will have nothing to do with the light functioning. all the relay does is switch power from Hi beam to Lo beam so one of the beams should light up. Testing at the light connector will show if the power is getting there and will indicate which terminal is getting power. I am going to guess your problem is incorrect polarity at the connector. Just switch the ground to another terminal of the LED and I suspect one of the LED's will light up.

[John Weyand]

Looking at the schematic--#57 is the parking lights. That will not have voltage at full out position (only half out). It appears that # 58 is the headlight terminal.

[Jim Karaba]

# 56 is the headlight terminal

[Hugo Karasawa]

The headlight relay is for the flash high/low switch. Check how this switch works in Greg Bryan's article which appeared in the 356 Magazine January-February 2015 Volume 38 - 5 .

If you pull half way the switch, the park lights terminal 57 have 6V, if you pull all the way you do not have 6V at terminal 57. See the diagram.

The terminal for the headlights is 56 .

[Hugo Karasawa]

Did you do a complete paint job ?
Like David Jones said, you have a bad ground. You need to scrape the paint at the grounding points.

[gregg hake]

Thanks for all the input, gentlemen.

I will begin checking things tonight. My car is a complete strip down and repaint, so there is a pretty thick layer of paint on everything. I have been very conscientious about scraping things where grounding is required so I think I am OK there. The polarity of the headlight connectors is a possibility as I get zero lights right now.

My harness is "new" although I purchased it from Y n Z 20 years ago and just got it in place in the past year.

My big picture problem, besides the polarity, is that I am not grasping the relationships between the relay, dimmer switch, and the headlights. Seems like a puzzle to me . Also, the wires that come from the dimmer switch do not match what the various diagrams say I should be seeing so I am taking that apart tonight to verify what is what. From what I am hearing, I should be seeing at least one headlight light up regardless of what is going on with the relay and turn signal/dimmer switch.

I am literate on million dollar radio systems...but this old stuff is throwing me for a loop.

[Hugo Karasawa]

Gregg,
What model is your 356 ?
Check at the fuse box if you have voltage at fuses 9 and 10 when you pull the switch all the way. Check also if you have voltage at fuses 10 and 11. If there is voltage at any pair your problem is not at the switch.
Next check at the headlight connector, do you have voltage at any of the three female spades when the switch is pulled all the way? If you have voltage at any of them then your problem is polarity. You have to change how the connector is wired.

If you want to better understand how the 356 electric system works read all the articles that were published in the magazine.
There is an article (march april 2017) where it shows all the harnesses with the wire colors so you can check if your harnesses are the same.

[Doug McDonnell]

Pretty sure he has a 62B

[Hugo Karasawa]

Here some pictures of the headlight connectors.
The back side is the one that has numbers
# 31 is ground
# 56a high beam
# 56b low beam

Front side
Ground is the terminal that has a notch in the connector
Low beam center terminal
High beam opposite to the ground

[gregg hake]

Hi All...
My car is a 356 B T6 Cab.
Last night I reassembled my steering column, which I had disassembled the night before so I could verify it hadn't been messed up. I wanted to inspect it because the column/dimmer wiring was the same wiring that was on the car when I got it...and at least one of the wires colors didn't match anything I had seen in documentation. I verified all was OK...and re-marked the odd colored wire.
Then I re-connected the light switch and compared the highs and lows as per the tables many of you suggested or sent me. All seems OK.
By then, it was bed time so I will continue with your many great suggestions and checks tonight.
Part of my problems are that I only get maybe an hour a night to look at this stuff because of the nightmare traffic we have to contend with in the Seattle area. A beautiful place when you see it on TV...but a nightmare to live and work in due to the unsolvable traffic. I spend 3 hours a day on the road doing a 20 mile commute so my spare time is limited !