lights flickering on decel

[jozuah]

When getting off the interstate after a 15 min drive at 75-80 MPH ( the flow of traffic in this area ) the headlights flicker and the charge meter on the dash drops to less than 12V then back up to 14.4 or so then back down, the entire time lights flickering.
so far i have done the following:

*cleaned the batt. terms and reconnected them.

*load-tested the charging system with an old school bear arbst machine i have. Checked out fine with no flickering.

*cleaned the terms on the alt. itself and checked for resitance between the alt and neg batt. cable. tested 0 ohms. on the 10K scale on a fluke 88.

im stumped, so i turn to your knowlage. only other thing i can think of is a VR on its way out.
joshua

[rodeo02]

Like you say, it could be a weak battery or charging system issue. My experience with the light flicker / voltage drop thing on several different vehicles, has been it coincides with a hi amp draw item switching on/off. TB's are highly electrical dependant and the our power spply is pretty much maxed out. My *theory* on the 2004+ 4.2's is the air injection reaction (AIR) blower motor is one of the highest amp load items on the truck. When that thing kicks on/off, the lights will flicker. Not sure of a way around it other than getting a higher capcity alternator or battery.

Joel

[jozuah]

This AIR you speak of, is that the blower moter sound i hear during first startup of the day? runs for about 30 seconds then stops. freaked me out the first time i heard it.

ill replace the ALT. before heading to utah this december to ward off any problems.
thanks for your reply joel.
Josh

[rodeo02]

Originally Posted by jozuah

This AIR you speak of, is that the blower moter sound i hear during first startup of the day? runs for about 30 seconds then stops...

Yes, that's it. The blower is under the truck, about under the drivers seat. It's suction source is at the clean air tube down stream of the airfilter box. The blower slightly pressurizes the clean air & then blows it into the cylinder head just upstream of the exhaust manifold. Theory is- adding oxygen to the cat, helps it light off quicker and work more efficiently. I'm not sure if the AIR blower runs at any other time other than warm-up, but it's motor is a hi draw item. Check the size of the power cables to it.

Joel

[brittoncharles]

Were you able to get this resolved? I have the exact same problem and would like to fix without depending on the dealer.