Bad Earth Problem

944Fripp · Apr 11, 2012

I've had the S2 for about 3 years now and it's ALWAYS had one side light dull compared to the other (on the passenger side). Normally it doesn't bother me but the missus pointed it out about a week ago and it's annoyed me ever since!! [

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Now I know this is a classic "bad earth" problem but I'm really no good with electrics at all! So, I have a multimeter and naieve confidence so what do I do first and where do I look?! By the way, I've already tried to remove the sidelight pod but the bolt/screw keeps turning without actually coming free. Am I going to need to remove the bumper?!!

Thanks all.

Copperman05 · Apr 12, 2012

Its def not the bulb? would try this before messing with wiring.

Edd

VanhireBoys · Apr 12, 2012

Hi Tom
Id do what Edd suggested and change the bulb.. A right pig of a job in fairness. If this dosent cure it then take off "the batwing" which is under the front bumper. This will give you access to the wiring plug for the lamp itself. Its a 4 pin affair. The pins are usually marked 1-4. Pin 2 is the ground. Pin 3 as far as I can see is your sidelight. Get a secure way of connecting these direct to the battery on the lamp side. This will tell you if the problem lies in the loom or the lamp

That earth is shared with the horns - Fog and driving lights along with the wash pump as well. Are all these dim...?

Let us know how you get on !

zcacogp · Apr 12, 2012

You've asked two questions; what is likely to make one side dimmer than the other, and how do you remove the driving light cover!

Removing the cover is a pain in the bum if it hasn't been off recently. You need to remove the two small clear plastic bits of trim either side, which are held in with screws with a slghtly odd thread arrangement. I am guessing it is these that you are finding turn without (apparently) doing anything. If so, I'd suggest levering them out very gently with a small screwdriver while undoing the screws - this should make the thread bite and start to work. (This explanation will make sense once you have the screws out!) You then have to remove the four screws (two on each side) that hold the light cover on, and these are the difficult ones. Peanut did a thread about his here:

http://www.porscheclubgbforum.com/tm.asp?m=673174&mpage=1&key=cover%2Cdrillò¤˜¨

... and that has some useful photos in it as well, and is worth a read.

OR you can remove the batwing and try going in from behind, as Donal suggested, but I'm not sure whether this gives you access to the bulbs themselves.

Once you have made your way to the bulbs, it's a simple series of electrical tests to find out what you want to know. Connect both bulbs across the battery and find out if one is dimmer than the other. Make sure the contacts on the back of them are all clean. Connect your multimeter to the terminals in the bulbholder to make sure they are both getting a good solid 12.7v. Connect your multimeter between the earth contact on the side of the bulb and a known-good earth on the car and see what resistance you see, and whether it is greater on the dimmer side.

Alternatively, you can simply tackle the earths - they are easy to get to, and are readily cleaned up. This is quick and easy and doesn't involve taking the bulbs out and may well solve your problem! This thread:

http://www.porscheclubgbforum.com/tm.asp?m=680595

... has a photo of the earths, about 3/5 of the way down, which will help you find them. (It may be worth reading the whole thread as well for other ideas on how to improve your lights.)

Oli.

ETA: Taking the cover off the light unit is a good idea, although a difficult job. The screws are probably corroded into place, and while removing them now will be difficult, removing them later (when you actually need to change the bulb) will be harder. Getting the screws out and changing them (replace them with M4 stainless, cap insert head screws, with a good smear of waterproof grease on the threads) could be considered preventative maintenance and will mean they are never difficult to remove again. I await the day when scruffy S2's and Turbos are scrapped because they fail their MOT on a blown lamp, and it's impossible to remove the light cover ...

VanhireBoys · Apr 12, 2012

ORIGINAL: zcacogp

OR you can remove the batwing and try going in from behind, as Donal suggested, but I'm not sure whether this gives you access to the bulbs themselves.

Unfortunately you cant get to the bulbs - Only the connection !

This looks like a been there seen that bought the tee shirt Oli ! [

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zcacogp · Apr 12, 2012

ORIGINAL: VanhireBoys

ORIGINAL: zcacogp

OR you can remove the batwing and try going in from behind, as Donal suggested, but I'm not sure whether this gives you access to the bulbs themselves.

Click to expand...

Unfortunately you cant get to the bulbs - Only the connection !

This looks like a been there seen that bought the tee shirt Oli ! []

Ah .... I did wonder!

No; when I needed to access a bulb I did it the hard way and took the front cover off. Reading your post, I did wonder whether I had made a rod for my own back but you have confirmed that I didn't!

I reckon it's worth re-iterating the point about getting the front cover off being preventative maintenance tho'. I had to change one bulb, and was so surprised by the state of the screws I took the other side off as well to see how bad that was. On both side I replaced the screws (but had to drill a couple of them out, which made a simple job into a pain in the neck.) Now, with SS screws in their place, it won't be a problem again.

Oli.

944Fripp · Apr 13, 2012

Holy under tray!!

Sorry, took me ages to work out what a "Batwing" was and couldn't resist the pun. [

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All great advice as ever! The clear plastic bits come off no problem but its the screws in behind them that keep turning. I suspect I may have to employ bruit force to sort this but agree with your synopsis, this needs doing anyway.

Ta!

944Fripp · Apr 14, 2012

OK, it all seems sorted now.

I did have to do it the hard way though! The clear lenses were not a problem, they came off fine. The light unit was a bu***r to take off though. All 4 bolts neede to be drilled and all 4 heads snapped off.

3 of the 4 remaining studs twisted out of the grey plastic housing with mole grips but the other did not budge. After the application of a delicate and precise use of a hammer and a drill bit I ended up pulling the brass threaded ring right out of the plastic! This left a hole large enough for the M4 screw to go through so I made a bodge:

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Basically the M4 nut is glued into position using epoxy resin! The white plastic is used to pack out the nut so that it cannot rotate against the plastic rib around it. I used an M4 screw with about 1/4 turn remaining to locate it. Once it dried it worked a treat.

Whilst this was drying I tested the sidelight and much to my amazement it worked fine!

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I replaced it with a new one anyway as the connector looked a little worn.

I then separated the two parts of the clear lens covers (either side of the light unit) and cleaned these up.

Finally, put it all back together and hey presto!

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It now works.....kind of!

When I backed the car out and went to double check it was not on at all! Gave it a tap and on it came!

So, I'm going to do the other side at some point and will probably replace both units as most of the remaining screws are pretty corroded. Will also double check all the connectors but I take comfort that it's either on or off now rather than just dull! Also, that I can now get to it easily!!

Thanks for all your help guys!

zcacogp · Apr 14, 2012

If you take the unit out of the bumper and drill the back of yhe obstinate screw stubs with a 2mm drill they usually loosen and xan be taken out with a pair of mole grips. you do need a stand drill and a steady hand tho, but you can get them out.