911Freshy

Having great fun tooling around in my 'new' 86 Carrera Coupe. Actually just drove it for the first time at night and noticed something strange. The headlights and instrument lights dim and then brighten at varying intervals, as if they were cycling or something. It does not affect the drivability of the car in any way and nothing indicates a charging problem (the alt. light does not illuminate at all). Not sure if it's related, but the seatbelt warning light also lights up/goes off at varying intervals as well, even though I am buckled up. This only bothers me to the extent that it may be (?) related to the headlight issue. Can anyone offer any guidance?

Peter Zimmermann

You've got an alternator/regulator problem. Have it checked before it (1) leaves you stranded, or (2) a high voltage spike damages something in the car.
Pete

911Freshy

Thanks. According to the maintenance records, the previous owner replaced the alternator at 80K (car has 128K currently). In light of that, is it more likely the voltage regulator, assuming that the alternator only has 48K under its belt?

Chris Holcombe

In my '86 the lights pulse a little at idle but smooth out as soon as the RPM increases. I assumed that the "cut in" RPM for the alternator to start charging was right around idle and the pulsing was alt just starting to charge (old BMW motorcycles do the same thing) but now Mr. Zimmermann has me worried so I think I'll check the voltage.

911Freshy

My problem happens at speed, so I think I definitely have an issue.

Saakey

well since it's much easier and cheaper for the regulator, i would start there anyway

911Freshy

good point - i believe it's an internal regulator? is this just an easy replacement or do i have to open up the alternator?

Saakey

yeah internal, but externally mounted on the alternator IIRC ..keep us posted!

Peter Zimmermann

Freshy: Unfortunately the alternators fitted with internal regulators only have a life expectancy of about 40-50K miles. Sure, there are some that last a lot longer, but on average yours has entered the trouble zone. You might get away with just a regulator, but it's best to do a rebuilt exchange using a competent source.

Chris: You're very observant, which is a good way to not get stranded with alternator trouble! Check the voltage at idle, and while holding the revs at about 2500, with and without headlights.
Pete

SPDRacer

My old 911 T did that before my battery completely died a few hours later. It turned out to be the wire to my voltage regulator, so I would check your vr since of course yours isn't an external one like mine.

rbcsaver

My 84 had similiar issues as the turn/high beam stalk was dying. Did the car have H4 or similar upgrades? Just a suggestion to consider this too,
regards,
Steve

DGaunt

Best comment is get a VOM on it and check voltages. That will confirm or eliminate the Alternator before you spoend time chasing other things like switches, which can fail but you have to approach this methodically.

donnieknoxville

Just had a very similar issue with my 1987 911 Cab which was solved by looking under the dash where the wires connect to the headlight switch and ignition switch. Before changing, I notice that the connector was just a little ****-eyed so I pulled it off and put it back on securely and problem was solved.

Don

911 Rod

I "had" the exact problem with my 86 911.
The mechanic I used claimed it was an electrical connection and he would take off the steering wheel and spray down the connection. I told him to forget it I rarely drive at night.
Then .... after a spirited trip of 3 hrs, the 3 hr trip home became a nightmare.
Regulator died and I boiled over my battery. Big mess, big stink. Had to keep going, as I had to pick up my daughter. Even though I washed the trunk with baking soda, I'm sure there is damage.
Had the alternator rebuilt and guess what? No more flickering headlights?
Every car I have owned has had a voltage meter, except this one. Grrrr.

911Freshy

Thanks to everyone for the advice. It has not had the H4 upgrade, and I don't think it's the turn/hi beam stalk as that seems to be functioning just fine. In order to check the vr or alternator with a voltmeter, I assume I will have to remove the fan and the shroud, correct? I printed a voltage regulator remove/replace procedure from a pelican parts tech forum and it seems to be pretty straightforward. Anything else I should look out for? Again, thanks.

Todd