Headlight wiring

[wingco]

Hi

I have a problem with drivers side headlight. When I put my lights on the drivers side is a dull and orange/yellowy sort of colour. I have changed the bulb so know it is not this. The only thing I can see is there is a yellow & green wire ( earth I presume ) which is connected to the shell but not connected to the light unit so must of come out/away from where it should live.
So question is where does the yellow & green wire fit in the light unit and is this the most likely solution to my problem.

cheers
Simon

 

[Guest]

try the connection to the shell take it off clean well and repalce any crimp lugs sounds like a poor earth

Paul

 

[Diver944]

The actual wire from the socket to the bulkhead can break inside the plastic sheathing. Caused by years of flexing when the popups go up and down. A good auto electirician (with tiny hands) can splice a new wire in

 

[Fred Hindle]

As a general thing - weak bulbs (of any description) can often be traced to bad earthing. This will also cause the bulb to blacken.
Check all earthing points, give them a good clean and if you so wish apply some petroleum jelly to the screw / bolt etc. This may hopefully solve your problem.

Cheers,

 

[924nutter]

All earth wires on the Porsche are brown, so the yellow green is not a bona fide earth, but it may be a secondary earth that someone has connected at some stage due to the loss of the original. I suspect if you take a close look you will discover that both filaments are on at the same time. The headlamp plug has its own earth, and you should check its integrety because if the earth return is broken each filament earths through the other, but doubles the circuit resitance hence the bright orange glow. It is not unknown for the any of the 3 wires to break at the point behind the headlight where they flex the most. The earth broke on my 924 and the main beam wire broke on my 944s

 

[wingco]

cheers chaps. One last one, where does this earth wire connect to on the headlight unit?

Simon

 

[924nutter]

ORIGINAL: 924nutter

All earth wires on the Porsche are brown, so the yellow green is not a bona fide earth, but it may be a secondary earth that someone has connected at some stage due to the loss of the original. I suspect if you take a close look you will discover that both filaments are on at the same time. The headlamp plug has its own earth, and you should check its integrety because if the earth return is broken each filament earths through the other, but doubles the circuit resitance hence the bright orange glow. It is not unknown for the any of the 3 wires to break at the point behind the headlight where they flex the most. The earth broke on my 924 and the main beam wire broke on my 944s

The plug on the back of the lamp has three wires, yellow (low beam), white and brown, (earth) up to the first connector then yellow/black (fuse 1) and white/black (fuse three) for the left hand light. Fuses two and four supply the right hand light.
The earth bolts to the monocoque at the earth point just behind the left headlamp. Without looking, icr if the right hand light has its own earth.

 

[Vollblut]

ORIGINAL: Diver944

The actual wire from the socket to the bulkhead can break inside the plastic sheathing. Caused by years of flexing when the popups go up and down. A good auto electirician (with tiny hands) can splice a new wire in

Just had this happen on my 951 and it was indeed cracked wires inside the sheathing. It happened on both sides, actually. On the driver side it was blowing the low beam fuses and I only had high beams. On the passenger side I had no low beam and it kept blowing the fuse as well.

Cut through the headlight harness sheathing right where it's attached to the headlight bucket frame with a wire tie from the factory, spliced the cracked wires back together, sealed it with electrical tape, and all is well again.

 

[Mike_Pollock]

The nearside one is easy to see - the brown wire screwed to the outside of the chassis rail -

The Offside one is actually on the outside of the chassis rail as well but underneath the headlight pod.

Hope that helps - but would say that most headlight problems come down to the link to the pods as the regular movement work hardens the
wires and although they look ok they have high resistance.

 

[Mike_Pollock]

Not really, they are to the headlight leveller but they do the same, link from the loom to the moving pod.

I've had problems with one side on each of my 944s.

 

[Mike_Pollock]

Thanks for letting us know what sorted the problem - always good to know for the collective memory!

 

[944Scott]

ORIGINAL: A9XXC

The nearside one is easy to see - the brown wire screwed to the outside of the chassis rail -

Hmmm what is that connector that is foremost in the picture connected to? im sure this is not connected to anything in my car.

 

[Tom]

Hi Richard,

This morning I was doing a little pre-MOT check over and discovered that my nearside headlight wouldn't come on full beam (but was fine on dip) - all the other lights were fine.

• Checked bulb and that was OK.
• Checked bulb and that was OK.
• Replaced the fuse and it blew.

I proceeded as follows:

• I took the blown fuse and tested the resistance from the bulb end of the fuse to ground (with the bulb unplugged) and confirmed I could vary the amount of short circuit by wiggling the cable near where it flexes on the headlamp unit.
• Note for others investigating similar problems - For some reason there was always about 50 ohms to ground. Not sure what that is but the wiring diagram shows a connector G15 in the passenger footwell but not what this is connected to.
• Read your thread and this confirmed my suspicion that 21 years of headlamp popping up and down hadn't done the wiring much good!
• After stripping all the outer rubber insulation back, it was clear that there were multiple issues: All the wires had the insulation cracked in several places and the white & black wire was snapped off entirely, so it could short to the other two (which were cracked at the same point).
• With all the shorts and the breaks fixed and a new fuse, main beam restored.

Thanks for your thread and the information that it has captured: It's always good to get some confidence from other owners before stripping insulation and cutting wires []

 

[Mike_Pollock]

That plug is to the headlight leveling motor.
Early cars dont have them and I'm not sure when they started fitting them.