Hello everyone, Quick Question....
When I start my 67 coupe and turn on the headlights, (I just noticed it a few nights ago, Previously it was in a different state, so I'm finding out some of it's quirks so to speak) I notice that they seem to Pulsate from brighter to dimmer and back again along with the green back-lighting dash instrument lights.........Any insight on why they might be doing this.?????...Thanx in advance...Trooper
Does the brightness fluctuation go away when you raise the RPMs?
If so I'll bet that the alternator is not putting out enough current at idle to keep the electrical system voltage constant. There could be several reasons for this, including a faulty regulator, weak or failing alternator or battery, excessively low idle speed, poor electrical system ground(s), after market electrical accessories drawing more current than the stock alternator was designed to supply at idle (including higher current than stock headlights) .... etc.
One thing for sure, the voltage on the electrical system is fluctuating which is causing the lights to pulsate -- probably because the regulator is cycling the alternator field current up and down as it hunts for the correct level to maintain the system voltage.
Assuming the alternator pulley size is stock, I would check the idle speed, make sure the battery, connections and grounds are in good condition (always a good idea), and if all of those items check out then see if I could borrow a known good regulator and try it out. If the problem is still there then I might see if someone could test the alternator current output at idle rpm and at full output rpm. If one of the alternator diodes or brushes has failed it would probably lower the alternator output current and this may be more noticeable at low rpms but still give enough output to charge the system at road-speed rpms.
Lots of places can supply higher output current alternators, and if everything checks out OK and you still have the problem, perhaps you can fins an alternator in a stock size case that puts out more current, but make sure it does so at idle (most folks give output current at a fairly high rpm and fail to give the output at idle unless you specifically ask for it.)
If nothing works then tell your friends that this mustang is equipped with the extremely rare 'disco lighting' factory option ;)
steve
Tro> Hello everyone, Quick Question....
Start by carefully checking all the circuit connections to make sure they are clean and tight. A bad ground seems to be the most common electrical problem. If it's only at idle or just above that, you'll be needing a new altrnator/regultor soon. If it's worse at higher rpm's (>1500), then it's probably the circuit breaker and/or the switch.
I had this problem with my '70 Cougar 351C. I solved it by installing a Chevy 12SI alternator, using a wiring harness from M.A.D. Enterprises. The part number corresponds to a 1983 Z-28. This installation does away with the voltage regulator altogether. The only drawback is that it required replacing the OE dipstick with a chrome aftermarket unit, which has leaked at its base from time to time when not sealed real well with RTV silicone. But this was on a Cleveland, so you probably won't have that problem.
180 Out TS 28
TS #11
"Stuart&Janet" wrote in news: snipped-for-privacy@golden.net:
Another one for the archives. Thanks, guys.
BTW, how's the GM alternator work on a 302 with ud pulleys? I've been replacing batteries about every 15 months.
Joe Calypso Green '93 5.0 LX AOD hatch with a few goodies Black '03 Dakota 5.9 R/T CC
Ive had the headlight pulse for awhile but tonight on the way home they started intermittent flashing...I know this is just a short somewhere but I sure wish this car would be nice to me for once
The flashing is most likely a bad circuit breaker in the headlight switch. A lot of folks are using relays to power the headlights direct and using the switch to activate the relays. You get brighter headlights in the deal and often you can save yourself replacing the headlight switch as the lower current required to run the relays gets rid of the problem of the breaker tripping. StuK
You've been giving your car its fair share of compliments, haven't you?
That usually works for me. Either that or I badmouth it and then tell it I'm going to sell it. It either dies or runs like a champ and magically cures itself.
For one tank of gas, anyway, then it's back to the same old routine.
JS
I had to nurse my '87 beater home tonight with a bad voltage regulator. I have a
70 mile commute. I kept patting the dashboard and telling her how good she was. I drove home with no lights, heater or even the radio on as I watched the voltmeter slowly falling into the 9volt redzone running on pure battery power. She stalled in my driveway! I feel like painting nose art on her like B-17 that made it home after a direct flack hit! I think I'll wash her tomorrow as a reward! StuK
Congrats on making it home. That's always miserable. I've been there before... no wipers in the rain at night, no lights on, using the e-brake as often as possible as it doesn't light the brakelights. Yes, been there many times. When she makes it home, she definately gets rewarded. I'm not always happy that something requiring that drastic of measures happened, but if she gets me home, that's all I'm after.
Getting from point A to point B without that sudden, unexpected stop at point C is always the key.
JS
drove home with
falling into the
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