Jump to content

Dead lights


MonkeyChap

Recommended Posts

Happy Christmas All !

I'm a bit stuck. I've got completely dead headlights (H4 lamps on an 84 carrera). It all started when I switched on the headlights and smoke came from under the dash. I switched them off, but couldn't see anything burnt down there. When I tried again, the main headlights were dead and I was only getting sidelights. As of today, I've got neither. I checked the fuse box, and they're all intact. I'm getting 12V to the thick red wire into the headlight switch (at all times). 

Any ideas what to check ?  Are there any in-line fuses elsewhere in the headlight circuit ?  All the wiring diagrams online seem to slightly different to what I'm looking at (in terms of wire colours coming into the switch). 

 

Thanks

 

Ian

Link to comment
Share on other sites

  • Replies 54
  • Created
  • Last Reply

Top Posters In This Topic

Top Posters In This Topic

Posted Images

Ah man what a pain, You need to find the burnt stuff to sort this out. Disconnect the battery and start sniffing / tracing the origin of the failure and then repair / replace as needed. Dont try the lights again until you have found the problem otherwise you could just be making things worse.

Bit late now but you can fit relays to protect the factory headlight circuit from overload, something like this:

https://forums.pelicanparts.com/porsche-911-technical-forum/366730-new-headlight-relay-kit-available-pelican.html

Plenty info online about the issue with pointers about where to start looking (stalk / switch etc).

Good luck.

 

Link to comment
Share on other sites

Just got back from the lock-up. I'd pretty much concluded it was the switch also. If I bypass it, I can light up the side-lights. I'm a bit mystified how the headlights are activated though. The wiring diagrams in Bentley and Haynes are fricking useless - both show a yellow wire which is nowhere to be seen, and also not apparent if it has to be earthed or live to light up the headlamps. 

Go on then Matt...how much ?

Link to comment
Share on other sites

Just got back from the lock-up. I'd pretty much concluded it was the switch also. If I bypass it, I can light up the side-lights. I'm a bit mystified how the headlights are activated though. The wiring diagrams in Bentley and Haynes are fricking useless - both show a yellow wire which is nowhere to be seen, and also not apparent if it has to be earthed or live to light up the headlamps. 

Given that it burned out, I assume there was an underlying cause (e.g. a short), or do they suddenly just go ?  Rather reluctant to replace an expensive part only to watch it go up in smoke. 

Go on then Matt...how much ?

 

Link to comment
Share on other sites

Yeah - seems to be OK. I've got always-on 12V to the red wire, and ignition only 12V to the red/white wire. When I pull the switch I don't get anything at the grey/black or grey/red wires. 

That was my first guess when I only had sidelights. Now I've got neither, and the switch does seem to be dead. 

 

Thanks 

Ian

Link to comment
Share on other sites

BTW - Does anyone know why they updated the design over the years ?  There's a really nice .01 model on ebay Germany which would be great in a backdate like mine, but I wondered if it was lower current rated than the later ones ?

Link to comment
Share on other sites

4 hours ago, MonkeyChap said:

BTW - Does anyone know why they updated the design over the years ?  There's a really nice .01 model on ebay Germany which would be great in a backdate like mine, but I wondered if it was lower current rated than the later ones ?

Wiggling fuses?  Adding Relays?  Surely there must be a better way? ;)

 

Link to comment
Share on other sites

Hi All,

I've pretty much isolated it to the switch - the problem is happening before the fuses. I think the relay idea is a good one - it's tempting to wire in the two spare relay holes in the fuse box, but the JWest solution looks way easier to do !

I can't see why there'd be more connections on later light switches though ?  Surely they've always just had front and rear lights plus instrument and reg plate ?

Ian

Link to comment
Share on other sites

Ian, I’ll go with Kenny’s recommendation as I have Jonny’s fuse board asssembly fitted to the Turbo and it is the dog’s boll@cks! With built in headlamp relays, your overloaded circuitry is solved! The spade fuses are bullet proof compared to the old torpedo type which require to be often fiddled with!

Regards,

David

Link to comment
Share on other sites

I pretty much did the same as described within the link Roy posted. On mine the PO had over turned the gauge light dimmer which can cause a short/ smoke effect. Remember to counter hold the switch shaft (there is a small hole in the shaft for this purpose) when unbolting the  knob otherwise you'll do the same. Take pics/ notes obviously of wire placement but also the orientation of the hexagonal insert. Worth a go before you blow 400 on a new one.

Link to comment
Share on other sites

Um...idiot question, but how does the switch enable dipped beam instead of side lights ?  The wiring diagram in Bentley seems to bear little resemblance to my setup (assume it's US ?), and Haynes has so many crossed lines it's useless.

I can't see which wire enables the main headlights instead of sidelights, and also whether that goes to earth or to 12v. 

I've jerry-rigged a temporary switch, but only got sidelights at the moment, and daren't fiddle with the other wires. I'm assuming it's the green/white wire as all the others seem to be either earth, 12v, instrument lights or the ones I'm using. 

Ta

Ian

 

Link to comment
Share on other sites

Thanks Roy. I'd spotted that one too. Still not obvious though, unless I'm being really thick. I'd guess it's the 56 one, but still not clear if that goes to earth or to 12V when the headlights are engaged. I can't test my switch either as it's toast.

Link to comment
Share on other sites

Easy ones first - the switch is controlling positive switching as there (from the photo) is no earth feed (brown wire). If I can get out of Christmas decoration removal duty (!) I'll have a look at what wiring info I have. My current interpretation is that 58 is connected to either 30 or 75 (the positive feeds) to operate the lights. Obviously 30 is usually a power feed on a relay so I would anticipate that's your headlight feed.

Link to comment
Share on other sites

Ok - 'should' be as follows: 30 is constant power (+12v), 75 should also have power but only with ignition on. 56 feeds the headlights so switch position 2 (headlights) connects 75 and 56. To test your headlights connect either 30 or 75 cable to 56 cable (via temporary switch) If 30 it should work anyway, if 75 should work with ignition on only. Hope this helps. Cheers Roy

Edited by Roy M
Link to comment
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
×
×
  • Create New...