Hi everyone, turn the mustang on this morning and the lights were pulsating. Recent changes, new headlight wiring harness, voltage regulator, headlight bulbs, parking lights.

When crusing with accelator down the lights puslate even in the dash, once I let off the gas the pulse stops and lights remain on constant.

Any thoughts as to what could be causing this?

 

my guess would be to start with the regulator. Sometimes new ones are bad.

 

I agree, there's a good chance it's the voltage regulator. It's a common problem. The contact points inside the regulator vibrate electrically. Buy an electronic voltage regulator. $30-$35 bucks at Napa.

 

I'll have to pick one up and see if that fixes the problem, pisses me off that I just spent 30 bucks on a new one, I should have left the old one in there! Thanks guys

 

Check all your grounds again also, loose/bad ground may have enough contact at idle but not enough when amps increased by alt. spinning faster. All your grounds should be to bare metal, no paint, rust, etc. between wire and metal.
Jon

 

Time for a new alternator. It's going out on you...

 

I'll check all the grounds again, it can't be a the alternator it's new as well.

 

check the voltage over battery on idle and start revving slowly (more and more) and see what it does.... if it creeps past 14V the voltage regulator needs looking at. I wouldn't be surprised to hear it goes all the way up to 16V....

 

Yep, it was the voltage regulator!! I had just put a new one in from CJ Pony Parts a few months back and had to replace it with a new one from Napa Auto Parts.