Skip to main content ↑ ↓
Topic: Headlight/parklight problem-pulsating/surging intensity (Read 2279 times) previous topic - next topic

Headlight/parklight problem-pulsating/surging intensity

I noticed today at work pulling in to park.  My lights (head,park,dash) flickering rapidly, this is very slight, but I am very conscious of things.  It is only in gear, and goes away when I shift to park.  Low RPM related, I have a used 3G installed.  What do I need to do fellas?:punchballs:
Mike

Headlight/parklight problem-pulsating/surging intensity

Reply #1 –
Get a voltmeter/ tester on it and make sure your 3G is working properly first .:D
Fox-less at the moment

Headlight/parklight problem-pulsating/surging intensity

Reply #2 –
Slight variations in rpm's can easily cause this. Having the air conditioning on can also make the issue appear more easily. Then there's other system draws that will also magnify the issue.

I agree with voltmeter. An buttstuffog one works great for this kind of check but again, so does a test light...and your cars' lights.

3G alternators suck at output at idle. I've had 4 so far as they are all pretty poor at an engine speed of 625 rpm's with the smallest alternator pulley I could find. All the other pulleys are stock.
1988 Thunderbird Sport

Headlight/parklight problem-pulsating/surging intensity

Reply #3 –
I noticed this morning, it is all my lights.  Dome, courtesy etc.  I will bust out the VM tonight.

What part of the alternator is responsible. The voltage regulator? Or something else?
Mike

Headlight/parklight problem-pulsating/surging intensity

Reply #4 –
It's likely regulated just fine, just that it isn't spinning enough to output enough amperage. The alternator may just be worn out or the load is too high for its specific capabilities. You can try a smaller pulley if it's not yet the smallest you can get. A larger crank pulley would also overdrive all your accessories.

If you have 14.4V with the rpm's up a little bit, I wouldn't bother with its (internal) regulator.
1988 Thunderbird Sport

Headlight/parklight problem-pulsating/surging intensity

Reply #5 –
I checked voltage at the battery 14.4, Voltage at alternator output 14.4.  I loaded all the accessories up...still 14.4 volts and perfectly steady no fluxuation on the meter. Checked with a buttstuffog meter also, nice and steady.

I switched the headlight switch with another used switch.  Exact same problem.  I noticed it is at all RPM's, not just low, it seems to be worsening.

WTF!
Mike

Headlight/parklight problem-pulsating/surging intensity

Reply #6 –
Make sure your battery is grounded to the body. Check the grounds on the headlights also.

Headlight/parklight problem-pulsating/surging intensity

Reply #8 –
Quote from: Trinom;329243
Does the frequency change with RPMs?


No, it doesnt.
Mike

Headlight/parklight problem-pulsating/surging intensity

Reply #9 –
have your alternator checked or take it apart and check all the diodes.
sounds to me that you have some ac voltage sneaking by. 

also,, pull your flasher and your turn signal relay out of the fuse box and retest.

since the pulsing does not follow the rmps but stays steady, it tells me there is a time constant circuit bleeding through which the only source of one of these I know of in our cars is the flasher/turn sig relay (two round things in fuse box, excluding time constant circuits in the security ckts).

check all your locations again with your meter set to a low scale AC volts.  Notice I didnt use the word "frequency" in our DC circuit.  There could be dirty DC current coming through if a diode were bad and you may not even detect it with your meter set to DC.

also,,
pull all unrelated fuses while this is happening as well, if problem goes away then at the least we know where to start on what fuse offered the new result.

Headlight/parklight problem-pulsating/surging intensity

Reply #10 –
I have no problem taking the alt out and having it checked.  Is that what the symptoms are leading to?  The output reads fine, just seems like "noise" in the system. Ive never had this weird problem before.

BTW it does have the original E7 ground wire as the main ground to engine.
Mike

Headlight/parklight problem-pulsating/surging intensity

Reply #11 –
Coming off of the negative battery terminal theres a smaller gauge wire(8 guage I believe) Make sure that is grounded  to the body-usually around the area of the starter solenoid. This wire usually breaks off and is often overlooked. Remember your headlights are grounded to the radiator support and not to the engine or directly to the battery. If this is the culprit once reconnected you will find your lights brighter-blinkers faster and dash lights brighter. Almost all electrical components in your car are grounded to the body and don't have a negative cable running to the battery. Just to test this quickly take a temporary wire and attach it to the negative terminal on your battery and touch it to the headlight negative wire. I believe its a 9/32 (7mm) screw on top of the rad support right behind the headlight (black wire). I'm not sure this is the problem but it is one of the easiest to check.

Headlight/parklight problem-pulsating/surging intensity

Reply #12 –
Quote from: kendoo130;329353
Coming off of the negative battery terminal theres a smaller gauge wire(8 guage I believe) Make sure that is grounded .


the car shouldnt start if that wire were broken

Headlight/parklight problem-pulsating/surging intensity

Reply #13 –
Quote from: jcassity;329255
have your alternator checked or take it apart and check all the diodes.
sounds to me that you have some ac voltage sneaking by. 


Can't he get enough AC information by setting the multimeter to AC V and hooking the red probe to ground and the black probe to the positive coming off the alternator?
1988 Thunderbird Sport