jeffrm Posted December 16, 2014 Report Share Posted December 16, 2014 I have a 240a pcm regulated on the 12v side of my truck. Every once in a while my lights will start to "pulsate" with rpm. I can tap on the alternator and it will stop, but it will start back after a good while. Could this be the brushes or regulator? Or something else? All wires are upgraded going to the alt and the plug is in tight. Quote 03 tahoe z71 4 death penalty 18s 2 ampere audio 3800s @ .5 each 18v 156.7 @ 35hz 158.5 @ 50hz Link to comment Share on other sites More sharing options...
jeffrm Posted December 16, 2014 Author Report Share Posted December 16, 2014 Alt on the left is the one in question. Quote 03 tahoe z71 4 death penalty 18s 2 ampere audio 3800s @ .5 each 18v 156.7 @ 35hz 158.5 @ 50hz Link to comment Share on other sites More sharing options...
rockFord_Expedition Posted December 16, 2014 Report Share Posted December 16, 2014 Does it only do this at idle? Or at any engine speed? Quote Old School/New School RF Build March 2015 SOTM Winner How to crimp large wire Link to comment Share on other sites More sharing options...
jeffrm Posted December 16, 2014 Author Report Share Posted December 16, 2014 Pulsating fluctuates with rpm Quote 03 tahoe z71 4 death penalty 18s 2 ampere audio 3800s @ .5 each 18v 156.7 @ 35hz 158.5 @ 50hz Link to comment Share on other sites More sharing options...
rockFord_Expedition Posted December 16, 2014 Report Share Posted December 16, 2014 Is it your OEM alt? Have you measured what your voltage is like when it does that? Quote Old School/New School RF Build March 2015 SOTM Winner How to crimp large wire Link to comment Share on other sites More sharing options...
jeffrm Posted December 16, 2014 Author Report Share Posted December 16, 2014 Its a mechman 240 internally regulated. Dont have a voltage meter on the 12v side yet but the gauge in the instrument cluster seems to move a bunch. Quote 03 tahoe z71 4 death penalty 18s 2 ampere audio 3800s @ .5 each 18v 156.7 @ 35hz 158.5 @ 50hz Link to comment Share on other sites More sharing options...
Nathan DM Posted December 17, 2014 Report Share Posted December 17, 2014 Just give us a call in the office. 888 MECHMAN Quote Link to comment Share on other sites More sharing options...
jeffrm Posted December 19, 2014 Author Report Share Posted December 19, 2014 (edited) Called in 2 days ago and was asked to leave a number and email address and I did so. Haven't heard anything yet. Edited December 19, 2014 by jeffrm Quote 03 tahoe z71 4 death penalty 18s 2 ampere audio 3800s @ .5 each 18v 156.7 @ 35hz 158.5 @ 50hz Link to comment Share on other sites More sharing options...
Nathan DM Posted December 21, 2014 Report Share Posted December 21, 2014 Sorry about the delay. Seems everyone is trying to get alts for Christmas. Try shooting an email to [email protected]. First thing I would check is the ground on the alts. Quote Link to comment Share on other sites More sharing options...
jeffrm Posted December 21, 2014 Author Report Share Posted December 21, 2014 Grounds shouldn't be an issue. Lol. Quote 03 tahoe z71 4 death penalty 18s 2 ampere audio 3800s @ .5 each 18v 156.7 @ 35hz 158.5 @ 50hz Link to comment Share on other sites More sharing options...
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