'74 Instrument Panel with backlit heater lever positions

Trying to add red LED's to the far right heater section of the instrument panel lights. The original bulbs have never worked and I cant get the LEDs to light up either. Does anyone have a link or pictures on how the wiring should go please.?

Edit: forgot pictures…



I'm guessing both bulbs have to be in for them to work ?

 

The samba has most of the wiring diagrams across the years for you:
TheSamba.com :: Type 2 Wiring Diagrams

There's not much to the wiring for that bit. Grey/red wire coming from the switch to the bulbs.
Are you getting 12v from that wire as it comes out of the switch?
Don't forget that rotating the switch allows you to dim the bulbs so it could be that you just have it twisted fully anti-clockwise.

 

Cheers for that colour circuit... I'm getting 7-12 volts ish to the gry/red into the top of the first bulb holder depending on dimmer position. Just not sure if that second gry/red from spade to the 2nd bulb holder and the earth tag off the bottom is correct.

 

As a start, have you got 12V on the bulb holders with the lights on? Dimmer control turned all the way up? LEDs in the right way round if they're the bulb type (they may be polarised)?

Should be an easy job.

 

Too slow!

 

You may find 7 volts isn't enough for LEDs. Best to find out why it's so low. What is it on the other bulbs?

 

I've got LEDs as follows: blue for high beam, orange for oil light and 2 warm white for the main instrument backlighting. All work fine its just these 2 on the end that I intend to put red LED in I cant get working. I know it should be simple and I've done more complicated stuff but guess I'm missing something simple...

EDIT: and voltage is only low when I'm messing with the rotary dimmer...I thought looking at a circuit diagram of those 2 would help a bit.

 

Odd. The lever illum source should come from much the same place as the pod dial backlighting. Worth checking continuity between the two? Or just checking the wiring.

 

Yeah there is power to the gry/red to back of that bulb holder on the right. I think both bulb holders have to be in place on that heater side to complete the circuit and me trying just one is never gonna work.

 

Odd, but possible. How are they earthed?

 

The brown spaded wire off the bottom of left plate... my problem is I'm missing a bulb holder ...

 

Looking at your pic, the RH one plate isn't earthed. The stripey grey/red should be paralleled up with the second bulb =12, not connected to the spade on the right. I'm sure VW wouldn't have used that colour for an earth, and both bulbs need to be in parallel, not series. The RH plate should have an earth wire attached.

Take off the stripey wire, attach the brown earth spade to the RH plate. That LED should then light up. You're half-way there!

I am v. jealous of your illuminated heater controls, btw

 

Found a picture of a similar panel for sale...the weird wiring appears to be correct...a strange in series line of wiring...

Personally i would daisy chain gry/red to each bulb holder and the earth to each spade as you say

 

Seems they did wire them in series, which is odd. Maybe to dim them down a bit.

You may be pushing your luck with two LED bulbs in series. There may be insufficient volts to turn both on, depending what's inside them. Could always rewire them in parallel. Easy enough to do.

 

It's probably meant to be two dim filament bulbs in series. With two red LEDs it should work, they will begin to light up around 3V , but two white LEDs will need 8 volts to light

 

^this, or something like it. LEDs won't do anything until you get above their forward voltage (which'll depend on the colour). Can be quite high.

 

I did check with the classic car led guy beforehand about dimming…

 

The connector my amazing PO used from fuse box to headlight switch to rear just fell apart…something else to sort while behind there.




And stray gry/red from back of hazard switch…

 

He speaks the truth! The bulb-shaped LEDs/limiting resistor will be calculated for 12V operation, so may not work below that. Just wire 'em in parallel - may not be too bright.

I did my instrument illum. using strip LEDs, and by a fluke you can actually dim them off the rheostat (not that you ever want to).