Headlight switch and loom fires.....DIY prevention

[CrazyDave 0]

Seen far too much of this lately.....Corrado headlight switch problem, smoke from behind dash, acrid smell of burnt cables and if really unlucky full on electrical fire and total loss of car :pale:

 

This is caused by the headlight switch developing a fault that sometimes shorts out the switch illumination earth feed wire (very small brown wire) with headlight live (very large) and bang....electrical fire.

 

Prevention is always better than cure so thought I'd post up this easy cheap little mod that will protect the small wire if the fault occurs. I don't normally like cutting anything on a standard car loom but in this case it's a must!.

 

Parts are all available from Maplin electronics so easy to get hold of.

 

Whole job takes about 30 mins to do, piece of mind afterwards....priceless :D

 

If you've already been unlucky enough to have had the fire behind the dash, you must check that the rest of the loom is OK before doing anything else. The wire that fries is loomed together with lots of other wire which also get insulation damage when this happens.

 

Also a great writeup on switch testing etc here by RW1 (that's the copyright issues sorted :wink: ) Plus info on testing new VAG switches that are faulty out of the packet :eek:

 

Also if you aren't confident with 'elastic trickery', get some who is to do this job for you :salute:

 

You will need:

Fuse holder. I got this one from Maplin for 59p Part Number PC78

stromlaufplan_gamma4.pdfDSC04079.jpg[/attachment:3c69jvfq]

 

Fuse. 200mA. Also from Maplin for £2.68 pack of 10. Part Number GL52G

Soldering Iron

Multicore flux solder

Side cutters

Wire sprippers

Small flat blade screwdriver

 

 

Here goes.....

 

1. DISCONNECT THE BATTERY!!!!!!!

 

2. Remove the switch from the dash surround. By gently lifting it at the sides with a small flat blade screwdriver. Ease one side out a little then work on the other side until it pops out.

 

ETKA Corrado.pdfDSC04086.jpg[/attachment:3c69jvfq]

The switch, early valver but similar on all models

 

Corrado92.pdfDSC04077.jpg[/attachment:3c69jvfq]

 

3. Locate the small brown wire on the connector at the back of the switch. It's the one on the top left as you look at the switch from the front.

 

climatronic wiring-Golf from May 01.pdfDSC04078.jpg[/attachment:3c69jvfq]

 

4. Cut the wire about 2" or 5cm from the connector. It needs to be just long enough to allow the body of the fuse holder to open up. Strip the ends back by about .5" or 10mm and twist the strands then fold it over. It should now fit nicely into the silver tags of the fuse holder kit with a little copper showing to solder (longer than shown here!)

 

passat climatronic wiring diags.pdfDSC04081.jpg[/attachment:3c69jvfq]

 

5.Fit all the fuse holder case over the cable ends, then the springs and finally the end caps. Then solder the end caps on.

 

2.8l 24v Climatronic system.pdfDSC04082.jpg[/attachment:3c69jvfq]

 

6. Fit the 200mA fuse to the holder. Twist and lock the fuse holder shut.

 

DSC04084.jpg[/attachment:3c69jvfq]

 

7. Double check everything and then reconnect the battery to test that everything still works! Then finally refit the switch into the dash surround.

[mic_VR 3]

Legend! :notworthy:

[lilfuzzer 1]

Nice solution and write up Dave think I may have to do that for piece of mind :clap:

[Wullie 1]

You know that is such a sensible mod I'm surprised that no one has ever done it before. Well done my man.

[Jim Bowen 1]

i did mine when i replaced the switch last :)

[Wullie 1]

i did mine when i replaced the switch last :)

 

Clever boy. I just need to be led by the hand most of the time. Would the fuse holder etc from Halfords do the same job? there isn't a Maplins near me.

[davidwort 0]

inline radio fuse holder should do the job, from halfords or anywhere, just make sure you have the right rated fuse so it pops first before anything gets hot!

[Henny 0]

Would the fuse holder etc from Halfords do the same job? there isn't a Maplins near me.

 

Yup, any old insulated fuse holder will do... mine's got a 1A blade fuse in it as that's the type the rest of the car uses... ;)

[ANDREW 30 0]

Looks fairly simple to do, i'll get mine done over the weekend!

[Wullie 1]

Looks fairly simple to do, i'll get mine done over the weekend!

 

I reckon I'll give it a go as well. Look out for the headlines. "Car bursts into flames in driveway" which is slightly better that "Car bursts into flame on motorway" This electricity stuff is puzzling, don't trust anything I can't see.

[emu 0]

I need to do this :)

[dragon green 5]

You know that is such a sensible mod I'm surprised that no one has ever done it before. Well done my man.

 

they did in 2005 ! and its a locked thread

viewtopic.php?f=19&t=31462

[STU175 0]

just went out to do mine and its already done... :D

does look as tho some one in the past may have had this happen, a few repairs to other wires near by

[RW1 0]

You know that is such a sensible mod I'm surprised that no one has ever done it before. Well done my man.

 

they did in 2005 ! and its a locked thread

viewtopic.php?f=19&t=31462

 

:wave: BBC repeats ! :lol:

 

The fuse may protect but the root cause is two fold.

 

1. The VW switches can be made with a short built in due to poor soldering thus the additional fuse it protects against a short. So it always worth a check before fitting the switch. The pre-fit check is between pin 31 and all other pins in all switch positions! as below

 

This because the manuafacturing solder fault bridges pin 31 (earth) and with the battery 12 volts direct and it's unfused. Hence why the fuse in the earth wire is fitted.

 

Checking a replacement headlight switch before fitting

 

With a meter on resistance setting, place one of the meter probes on the pin marked 31. Now in all three switch positions (off – sidelights – headlight), go round ALL the other pins. All should be open circuit with one exception relative to pin 31. If the switch has the original filament small bulbs fitted then pin 31 to pin X will show 16 ohms +/-3 ohms (unless it’s blown). If LEDs have been fitted, then on the ordinary Ohm settings on the meter (not diode test), it should be open circuit. If no direct short is detected in the any of the above tests, the headlight switch is safe to fit to the headlight loom in the dash.

 

Corrado92.pdfVW Corrado Light Switch Internal Illumination Schematic.jpg[/attachment:z8kf625g]

 

2. The headlight switch is damaged by heat from the two internal lamps which results in mechanical failure and possible short electrically.

 

Heres the switch with lamps fitted which generate a fair amount of heat............

 

passat climatronic wiring diags.pdfSwitch with Exisitng Lamps.jpg[/attachment:z8kf625g]

 

This is the damage caused, the plactic lever plastic becomes brittle and breaks off as well as the light lens being distorted and burned.........

 

climatronic wiring-Golf from May 01.pdfHeat damaged Headlight Switch.jpg[/attachment:z8kf625g]

 

The solution is to fit two bright green LEDs & resistors.............

 

2.8l 24v Climatronic system.pdfLEDs and resistors in situ in Headlight Switch.jpg[/attachment:z8kf625g]

 

The end solution looks like this....................

 

LED modifiied Headlight Switch installed.jpg[/attachment:z8kf625g]

 

 

If a short now occurs with the switch and the additional fuse fitted, the indication is that the ignition illumination of the switch does not illuminate (assuming its not just the small green bulb that has failed).

 

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[KIPVW 0]

:notworthy: :grin:

[Critical_Mass 10]

Simple yet effective. I will be doing this mod.

[VWVW 1]

….Iam now a bit worried after reading this post :( . My headlight switch is a bit skewered in opertation in the side light position and also I have noticed that the round symbol doesn’t illuminate either. It only illuminates at the headlight position.

 

I take it the switch could be in danger of shorting due to mechanical failure.

 

…Shall I disconnect the battery and take the switch out for inspection or disconnect the battery permanently and try and source a replacement headlight switch and get a led bulb and resistor on it ASAP?????

[Critical_Mass 10]

Thats odd... i think we've had this discussion before about the switch is only supposed to illuminate when on side lights, as the logic is that if you have the headlights on you should be able to tell cos its dark enough so no need to highlight the switch as being on headlights.

 

Could be a possible fault. I suppose if in doubt get it sorted. Also it would definately worth doing the fuse mod above.

 

I guess others will advise too.

[VWVW 1]

My headlight switch is a bit skewered in opertation in the side light position and also I have noticed that the round symbol doesn’t illuminate either. It only illuminates at the headlight position.

 

I will have to double check again when I get home this weekend

[RW1 0]

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Another headlight switch question by RW1 » 23.11.2005, 17:41

 

However, when I press it again on to dipped beam, the outer ring goes off. I thought it may be a dodgy contact, but when I turn the ignition off (the lights go to sidelight automatically) the ring illuminates again

 

Logic is correct as the ring is a sidelights only ON warning ring indication. So with/without ignition on in the sidelight position you get the ring. On headlights, it works only when ignition is knocked off, ignition off, knocks off the headlights, so the sidelights only warning ring comes on illuminates. Clever little diode buried deep inside the switch.

 

The Lamp symbol is always on when the ignition is on no matter whether the lights are on or not. Switch locator illumination.

 

Its in the owners handbook. :wink:

 

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[Wullie 1]

You know that is such a sensible mod I'm surprised that no one has ever done it before. Well done my man.

 

they did in 2005 ! and its a locked thread

viewtopic.php?f=19&t=31462

 

I'm not that old!! And anyway, didn't discover the best Corrado forum till recently

[Supercharged 2]

Guys, cheers for posting this up as I have been meaning to do this for a while... will make this a Sticky

 

Few questions - I did this mod a few years ago on both cars and like Henny used a blade holder and I'm fairly sure I fitted a 3 or 5 amp fuse...

 

Is this fuse rating low enough?? I think the lowest blade you can get is a 1 amp but I will go to Maplins at lunch and have a look...

 

I think I will also go down the LED route too as my headlight switch is getting noticably hotter since removing the Trimsport loom I was using.

 

Another thing I'd say is use a good quality fuse - I recently had a dead short on one of the centre console lighting wires and nearly set the car on fire - when I looked in the fuse box I found the 15A fuse had just melted the casing so looked bigger than the other ones but still had continuity! Fitted a VW one in there are re-shorted the wire whist repairing and it blew straight away as it should.

 

I'm fairly sure the above fuse came out of a box of 'Rolson' ones I had bought a few years ago (these are sold in Halfords / Maplins etc) so won't be using these anymore!

 

Anyone got the LED part numbers?? Probably best to fit 12V ones with the resister built in - Maplin also do these in various colours.

[JMC 0]

Just get the standard 3mm 12V led's from Maplins mate. Most of the switches are 12v (apart from the window switches) and the headlight one definately is.

[craigowl 0]

Grateful thanks to the electrical wizards :salute: (pleeze to make sure you keep zose droopy sleeves out of way, yes?) :wink:

 

Clever diodes in switch - sure - but plastic is made of dried snot from Westphalian cows.

[RW1 0]

Just get the standard 3mm 12V led's from Maplins mate. Most of the switches are 12v (apart from the window switches) and the headlight one definately is.

 

Too dim, tried that type first, miles dimmer than the standard little green bulbs. Tried Maplin's 3 volt ones, again at the time not bright enough. Needs a pair of bright LEDS. LEDs were green from maplin, part number N30BY http://www.maplin.co.uk/module.aspx?moduleno=45930

 

End up with a metal film resistors from RS Spares part number 144-295, 2.7K ohm, Metal Film 0.125w.

Now superceded http://uk.rs-online.com/web/search/sear ... &x=29&y=15

(You need this physical size to get the resistors in without fouling the mechanics.) Maplin at the time didn't offer 0.125w resistors. And note the two small insulating sleeves in the photo on page 1 of my postings.

 

The LED lens for the ring illumination need "damping" or it looks unbalanced so I painted a black blob of touch-up paint on the crown of the lens. This is the LED furthest from the dimmer control. Don't bother with paint on the other as it not as transparent and it needs the direct beam of the LED onto it.

 

The fuse I used was a 1 amp standard blade fuse like the Corrado's type. Dave's 200 mA fuse will work just as well. I tested the 1 amp fuse on a length of same wire across a battery's terminals direct. Fuse blew, wire - no damaged found, it was instant.

 

My switch operates a BRMotorsport headlight loom. It is always stone cold.

 

Sticky? Get ur finger out! Should have been done in 2005 :lol:

This topic has it all in one spot now for the headlight switch problems.

No excuses now!!!

 

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