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  View original topic: headlight relay
ladybug12 Tue Mar 24, 2009 10:43 am

Well guys, this wiring project just keep snowballing. I ordered & just received a new VW fuse block from Airhead Parts. It is a 12 fuse with the upper level for the relays. The one that I took out of my '72 Standard Beetle is the same except for the relay upper level. There is no configuration that matches my headlight relay. I wanted to use the original relay. There is one that is close but the one prong is backwards. Can I use a newer headlight relay? I don't understand why it would be different. The new fuse box is supposed to be a replacement for the original. I assumed it would be the same. Also it looks like fuse 4 & 5 are reversed but that isn't a big deal as long as I remember that when putting the cables back. I tagged all my cables as I disconnected them so I would know where they go when I re-connect. I basically wanted to replace the fuse block & replace some of the spliced wiring & update some or most of the connectors that were rusty. Things have been going fairly smooth until now.

Anyway, back to my original question. Do the new replacement VW headlight relays fit the new fuse blocks? It looks like I can't use the original relay. Also is the correct term for this part a headlight relay or a headlight dimmer relay? Are they the same thing or two different type relays? The original relay that I have is silver but it looks like the replacements are black. Bear with me, I'm learning as I go.
Thanks for your help!

jamesdagg Tue Mar 24, 2009 4:53 pm

Usually the fuse boxes have extra slots and you just insert the female spades into the ones you need.

As a last resort you could use a new relay that comes with it's own socket.

Be sure your new box has the same terminals "twinned" on the feed side. If not you may need to adapt with jumpers.

Seen this site?

http://www.nls.net/mp/volks/

jim

mnussbau Tue Mar 24, 2009 5:09 pm

Can you post up a photo of the original relay or the fuse box, or give us the part number off the relay? BTW, it's a "headlight dimmer relay".

jamesdagg Tue Mar 24, 2009 5:23 pm

I don't know if technically it's a relay.

Relays are used to switch a high currant load with a low currant switch. That's not what the head light thing does. The high currant passes through the switch.

This unit is just a remote activated SPDT switch with a hold function, meaning it stays wherever it was when the power goes off.

Hey, you asked! :D

jim

mnussbau Tue Mar 24, 2009 5:30 pm

:lol: Had me rolling! =D> I'll just say that Bentley refers to this "remote activated SPDT switch with a hold function" as a "dimmer relay!"

jamesdagg Tue Mar 24, 2009 8:29 pm

I looked it up!

It is a relay by the fact that an electromagnet switches the switch with it's circuit isolated from the switched circuit. It just has a different purpose than most. It does not eliminate high current from going through the switch. That's why when switching to higher output headlights or adding fog lights to the headlight circuit, another relay is used.

So this is called a latching relay.

"A latching relay has two relaxed states (bistable). These are also called 'keep' or 'stay' relays. When the current is switched off, the relay remains in its last state. This is achieved with a solenoid operating a ratchet and cam mechanism, or by having two opposing coils with an over-center spring or permanent magnet to hold the armature and contacts in position while the coil is relaxed, or with a remnant core. In the ratchet and cam example, the first pulse to the coil turns the relay on and the second pulse turns it off. In the two coil example, a pulse to one coil turns the relay on and a pulse to the opposite coil turns the relay off. This type of relay has the advantage that it consumes power only for an instant, while it is being switched, and it retains its last setting across a power outage."

jim

ladybug12 Wed Mar 25, 2009 6:18 am

OK-here are some pics:




I boxed in the closest configuration on the new box that matches the old box for where the headlight dimmer relay should go.

There is one problem - there is a little tab on the odd prong that is backwards when trying to fit into the new box. Here are some pix of what I'm talking about:



Here is a pic of the old box & where the relay was seated:


In the catalogs, the new relays have all "flat" prongs. I was thinking that a new relay should work then even though originally I was planning on using the old relay. I called Mid-America yesterday & talked to a tech guy. He said the new relay should work just fine. So I ordered a new relay.

I'm just wondering why they changed everything - the relay boxes & relays. I guess they want you to buy all new stuff.

Wish me luck. I took off work today to work on the bug. I was hoping to have it all put back together today but I guess that isn't going to happen. I hope to get most of it re-wired today anyway. I want to thank you guys for answering my dumb questions. As I said, I'm learning so much as I go. I am really enjoying all of this process too - even though it is frustrating at times!

ashman40 Wed Mar 25, 2009 8:18 am

jamesdagg wrote: I don't know if technically it's a relay.

Relays are used to switch a high currant load with a low currant switch. That's not what the head light thing does. The high currant passes through the switch.

This unit is just a remote activated SPDT switch with a hold function, meaning it stays wherever it was when the power goes off.

Hey, you asked! :D

jim

I asked the same question when I was working on mine. :wink:

I see you found that they are known as "latching relays".

The later VW headlight dimmer relay actually has two relays in it. One is a momentary and activates the "flash" function when you pull the lever. The second is the latching one that routes the power to either high or low beams.
Using common Bosch-style 30A SPDT relays, I can recreate the function of this single headlight dimmer relay... but it takes seven relays to replicate the function !


Ladybug12, if the physical spacing of the relay prongs will fit into the new "bridge" at the position you indicated, I'd just use a pair of pliers and flatten that tab that sticks out. the new ones don't have that locking bit and just use the friction of the five (smooth) prongs to keep it connected.


I also noted that the fuse box you bought is not the correct one for your year. The original '71-'72 fuse box had three fuses that shared a common bottom (#7, #8 & #9). All later 12-fuse boxes had at most fuses paired up. Also, it looks like fuse #1 and #2 should be paired on your new fuse box but aren't.

You can "fix" both by creating a couple of small jumper cables to simulate the missing connections. Use the thickest wire you can find (12-14 AWG should be good enough the distance is short and should be less than 10A). Jump the bottoms of fuse #1 & #2 together. Also jump the bottom of #7 & #8 together. That should replicate your old fuse box.

'69Custom Wed Mar 25, 2009 8:53 pm

Ah, yes, the typical Airehead Parts "direct replacement" clause! I remember my first purchase from them: a direct replacement interior lamp for my '69. HA! It was anything but! Had to install the thing backwards and modify the hell out of it to get it installed and working. Not to mention the bulb they sold me for it didn't fit the thing.

ladybug12 Thu Mar 26, 2009 4:56 am

Ashman - I know that the fuse box isn't the correct one for my model/yr VW but I wanted to replace it with the same one that I took out. When I first looked at the old fuse box I realized it wasn't the stock fuse box.

Well I ended up cleaning the old (original) fuse box that came out of my car and re-installing it with new fuses & some new connectors. I may install the new fuse box at a later time. I mainly wanted to replace some of the really bad rusty connectors and replace some of the poor slicing that was done by a PO. I had to get my car up & running soon so I can get it over to the guy who is doing my body/paint work.

I held my breath & started "ladybug" last evening after reconnecting all the wiring. Good News! She started right up & everything (lights, signals, dah lights, wipers, etc.) are working fine. Actually I surprised the heck out of myself that I actually did this. Down the road I hope to tidy up the wiring & change some more of the connectors but for now it's fine.

Thanks so much for all of your input. I have that one site bookmarked about the electrical info. It is a really good site.

bombero319 Thu Mar 26, 2009 7:58 am

is the old panel damaged? if not, you could clean it up and put it back in. the female spade connectors go in and out pretty easily. an abrasive ink pen eraser (the white and grey one) and some electrical contact cleaner and you're as good as new.

as far as your '72 not having the correct panel, here's a little story. my dad has a '72 std. he asks me to get him a fuse/relay panel on my next vist to my local self service wrecker. there were two '72s that day. they both had 12 fuse panels. so i grabbed the better looking one. when i took it to him he said he thought his literature said 10. when he opened the trunk to confirm, it had 12. on the next few vistits to the boneyard, i looked for 10 fuse panel. no luck. they're all 12.

ladybug12 Thu Mar 26, 2009 9:01 am

bombero- that's exactly what I ended up doing. I cleaned it up yesterday & re-installed it. I'm glad you said you had the same experience with the 10 vs. 12 fuse issue in the std. '72. I prefer the 12 with the relay platform above. My restoration is custom & not stock so I figured it really doesn't matter. Thanks for your input.

James or anyone-
Do you know where I can buy decent german fuses? The fuses I bought at the auto parts store are crap. They are labeled for German cars but I think they are made in China. The little silver piece is so flimsy & comes right off. I ended up putting back the "best" of the old fuses until I can get decent new ones. Anyone else have the same issue with fuses?

mnussbau Thu Mar 26, 2009 5:12 pm

Not German-made, actually these are listed as Made in USA. Hopefully better than what you bought.
http://www.oeveedub.com/mm5/merchant.mvc?Screen=CTGY&Store_Code=oe&Category_Code=bug-fuses

bombero319 Fri Mar 27, 2009 9:18 am

i got usa-made copper element type. they're made by Buss (little yellow tin with sliding plastic box). i got them at Kragen; i think you can order them online since there aren't any stores near you. other stores carry them i'm sure. don't use the aluminum element fuses if you can avoid it - use the copper ones. the contacts in the fuse panel are brass. dissimilar metal corrosion will be exponentially accelerated with the aluminum type. same holds true with the copper wiring -m brass terminals will corrode slower than aluminum.



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