low beams don't work

[derek murray]

A few nights ago when I turned my headlights (low beams) on they took a few seconds to come on. This happened a couple more times, but now they won't come on at all.

My high beams work fine, fuses are good, connections to the switch and stalk have been checked and seem ok, and the turn signal switch is less than a year old (25 hours max.)

Any suggestions on where I should start my investigation?

[makaio]

I would first check the lamps. I have a friend that had the same problem, and he went through almost everything, including replacing the high beam stalk, before he switched the bulbs, and that solved the problem.

[KTL]

Do you have power for the low beams at the headlight? Check for power right at the leads to the lightbulb itself. If you have power, i'd suspect your low beams are simply blown out. Strange that they'd both blow at the same time though. That could be another problem altogther. I simultaneously blew out my lowbeams just this past weekend due to a faulty voltage regulator that was spiking the voltage to almost 17 volts, and possibly more, while driving.

[arerrac]

This JUST happened to me! My highbeams were stuck ON. Pulled the swithching box and looked at the contacts. Really weird contact setup. (No german rocket scientist designed these) As it turns out, the hi-beam circut had over heated and melted the plastic seperating the hi-low contacts. Not wanting to drive at nite w/ the hi's on, it rigges the TIP of a zip-tie to place between the two contacts. Pressure from the two copper contacts keep the zip-tie TIP in place. Now tha hi's are off ant the lows and fogs work. Still need to replace the unit, but I can drive at nite and not piss everyone off.

Just a quick road-side fix.
-W

[Blaine Sellie]

Sounds like it is time to replace your turn signal/high-low switch. i just replaced mine also for the same reason. About a $100.

Blaine

[stomachmonkey]

Pull your switch and check it NOW.

Driving home one night and I come to a very dark part of my commute, no one else around so I hit the brights and it doesn't get brighter.

Hmmm, flick em off, no difference, flip em on, still the same, flip em back and forth quickly a couple of times and HOLY CRAP I loose the headlights all together.

Turns out the switch melted just like arerracs'.

Apparently a common problem.

And no you can not rebuild them once they melt.

Scott

[raceman]

yup,column mounted switch blown.Porsche runs power through the switch wich leads to accelerated burn out.The fix? Replace with factory part and install headlight relays so you can run the 80/120 watt bulbs

[derek murray]

the column switch is virtually new (less than 25 hours on it) and i have a m. sucro relay installed so i assumed the stalk switch would be ok... but i will check it all out tonight... thanks for the help.

[derek murray]

update....

1. I removed the steering column and clamshells and the turn signal / high low beam switch appears to be in perfect working order... no melting, pitting or any signs of wear whatsoever. I did not check it with multi-tester but will do so tomorrow after I review an electrical schematic.

2. The voltage regulator tested fine.

3. I bypassed the sucro headlight relay just in case... but still nothing.

4. There is NO current present at either of the 2 low beam fuses... (so I did not test for current at the bulbs).

5. High beams test fine, but when they are on there is about 0.3v present at the low beam fuses (0.0v when high beams off)

So IF the stalk switch tests fine, is it possible that one of the relay's located behind the instruments may be the cause of the problem? Or could it be the ignition switch? The light switch?

[RoninLB]

Originally posted by derek murray
update....


4. There is NO current present at either of the 2 low beam fuses... (so I did not test for current at the bulbs).

I guess I'll buy into your good sw.
so how about removing the firewall sw plug? then a little cleaning and using a razor blade to seperate the pins a little bit.

[stomachmonkey]

Hmmm,

Why is the column switch new? What was the reason it was replaced?

May be a clue to your current problem.

Scott

[derek murray]

update, day 2

1. I tested the stalk switch with the multitester and everything checks out ok... current is present at the yellow wire when the light switch is on.... same for white wire when high beams are on.

2. I replaced the five pin relay (headlight switchover so the schematic says) behind the instrument panel with a known working one... no change.

3. OH YA... NOW MY SIGNALS DONT WORK... emergency flasher works fine... was it caused somehow by my hand fumbling with the relay?... is it related to the low beam problem?... is it completely unrelated but just bad karma?... arrrgh!

BTW, electrics are not my strong suit... or did you guess that already... time for another beer.

EDIT: stalk switch is new only for the reason that my high beams didn't work when I got the car so I replaced the switch because I didn't know any better... turned out in the end to be the wires at the bulbs were all switched around (homemade harness by a PO)

[RoninLB]

Originally posted by derek murray

3. OH YA... NOW MY SIGNALS DONT WORK...... is it completely unrelated but just bad karma?... arrrgh!

Scott had an obviously bad stalk sw.
somehow the signals and hi/low are related. huh ?
I assume your wiring is correct.

do you have the old good stalk sw ?

[derek murray]

Originally posted by RoninLB
I assume your wiring is correct.

do you have the old good stalk sw ?

Ron,

I am assuming the wiring is correct as it has worked fine up until now... but I will double check.

I do have the old stalk which I will re-install to verify it is / is not my 'newer' stalk switch.

[Early_S_Man]

Derek,

While it still may be stalk switch related ... be sure to check the socket contacts for the switchover relay ... for overheating damage, corrosion, etc. 34 years is a LONG, long time ... and that socket carried the entire load for almost all of that long time!

[derek murray]

After Early_S_Man's reminder of the age of the car's wiring, I decided to start checking and cleaning the various component connections.

When I started removing the wiring from the main light switch, the faston connector at terminal #56 crumbled in my hands... the interesting thing is that I had visually checked these wires before, but on the surface they looked fine and passed my wiggle test.... well, five minutes, one new faston connector and some shrink wrap later the low beams are working again.

Thanks to all for the help.


...seems all so simple now