instrument lights are PULSING!

[robspeed325i]

im guessing this is an alternator on the way out... but is there any other reason why my instrument panel lights (everything) is pulsing like its dancing to an unheard beat?

[Dresden87]

sounds like your alt is either shot or just not powerful enough. I had to replace the stock one on mine for a more powerful one.

[Stevie30]

My lights have been pulsating for 12,000 miles. I've been expecting the alternator to go but it keeps hanging on.

[robspeed325i]

My lights have been pulsating for 12,000 miles. I've been expecting the alternator to go but it keeps hanging on.

Im afraid the regulator will fail and I'll fry the whole car...

[ETeurowerks]

Diodes have gone bad. Usually all the lights will pulse getting more intense as RPM's come up.

[robspeed325i]

Diodes have gone bad. Usually all the lights will pulse getting more intense as RPM's come up.

Heh, so i just need a regulator? Excellence! On the other hand, alternator prolly has 147K on it, better to just replace whole thing?

[DCColegrove]

Heh, so i just need a regulator? Excellence! On the other hand, alternator prolly has 147K on it, better to just replace whole thing?

You need the whole alternator...

The diode bridge is not part of the voltage regulator.

I wouldn't recommend a cheap re-build, I only use Bosch re-mans at the shop.

[Stephen]

or you need to stop twisting the dash lights knob :P

[Nick325is]

Could just be the voltage regulator on the back of the alternator. Mine did this and the regulator was the issue.


-Nick

[robspeed325i]

I went ahead and ordered a rebuilt/upgraded 130amp alternator from eagle auto electric (ebay guy from california). I'll be SURE to provide feedback regarding how -tehsuck it is.. ;)

it was $115 including shipping, no core charge/hassle...

[Charlie]

Could just be the voltage regulator on the back of the alternator. Mine did this and the regulator was the issue.


-Nick

+2, it sounds like a voltage regulator. That's a 10 dollar part vs a 115 dollar one.

-Charlie

[robspeed325i]

+2, it sounds like a voltage regulator. That's a 10 dollar part vs a 115 dollar one.

-Charlie

after talking to my dad, who is a retired electronics techpimp, i am convinced it is the rectifier (a $125 part on its own). the rectifier is the diode bridge that takes the A/C sine wave created by the movement of the rotor against the stator, and slaps it down to a solid DC +14.4v for the battery to suck its milk from. If the diodes are leaking or shorting, the DC output will turn into a square wave, which causes the pulsing I am seeing. I talked to him at length over the phone and we're sure this is what it is. Plus im getting +40% more charging capacity over stock with the new upgrade alty, so I'm happy to do the swap. (I have big lights and big amps planned.) 150k on the og alternator is just about enough under any circumstances, and after i pull it i'll test each diode and if needed replace the faulty one/s and keep as a backup in case ebay alty dies...

the regulator keeps the voltage from surging past 14.4. if it was the regulator, id be seeing the lights going SUPER BRIGHT then dying back down. instead i am seeing them at normal brightess, and then dying (as DC voltage is sucked down by AC wave), then back to normal again and again...

p.s. the regulator is a $30 part.