2002 F150 4.6L V8 pulsing lights HELP
 

Hey everyone,

so I have a 2002 F150 4.6L Triton V8 rwd.

i have a new battery and a new alternator

my headlights, dash lights, and dome lights pulse all the time when on. DRL pulse as well. They seem to pulse at the same rate as the engine.

The only code that i have pulled with an OBD2 is a vacuum issue in the gas tank.

any ideas what could be causing this issue? Thought the new alternator/regulator and battery would have fixed the issue but nop.

battery charges fine. No issues with starting.

pulsing only happens while engine is running.

Thank you.

Check all your grounds

So i checked grounds all look fine. Even went as far as running my own ground to the same point i have a ground coming straight from the battery, still pulsing.

Need to make use of MM the system. Yea you really can't look at ground and presume it fine. You mentioned a new alternator, so did you clean the alt mounting surfaces. Absolute ground is the alt case which transfers to the mount location on the engine. What's you alternator doing during the surge, I'd start there with an MM and do some tracking, find the surge. Since everything's surging, should have the ability locate a bad connection within the main cabling.

I had a similar problem when my truck was new. The whole electrical system was pulsing, even the window motors were fluctuating when going up and down. Service adviser told me it was a loose plug on the back of the fuse block.
Good luck.

Thanks for the idea LWJ, ill check that out today.

ran a ground straight to the alternator this morning to test if the alternator was having a bad ground but nothing.

ill post once i check fuse block.

Fuse block is solid.

Both of them?

Both of them? Service Adviser didn't specify.

He's referring to the fact that you have two fuse boxes. The one under the hood and the one inside the cap underneath the steering wheel