Headlights

I have an 05 trailblazer with 99k 4.2 4wd. The headlights flicker sometimes at night when I let of the gas. Tonight was by far the worst. It looked like I had pulsating headlights. The dashboard lights do it as well. When it occurs the battery gauge drops several amps as well but returns to 14ish amps after things level out. Any ideas?

Have the alternator diodes tested. One or two may be shorted.

Have the alternator diodes tested. One or two may be shorted.

Also check all your battery/alternator cables. Clean, tight, good grounds.

I checked all the grounds, cables, and battery today all were good. Can I take the alternator to a parts store to have diodes checked? Thanks for the ideas.

I checked all the grounds, cables, and battery today all were good. Can I take the alternator to a parts store to have diodes checked? Thanks for the ideas.
You can, and it's better than nothing.

BY FAR the BEST way is to take the WHOLE VEHICLE for a starting/charging electrical test. This will catch problems anywhere in the starting/charging system, including the wire harness that ties them all together.

I wouldn't bet against a defect in the voltage regulator circuit, either.

I checked all the grounds, cables, and battery today all were good. Can I take the alternator to a parts store to have diodes checked? Thanks for the ideas.

They can be tested on the vehicle providing they have the right equipment like an Autometer BVA-3000 or better. HTH

I might add to make sure they can provide you with a printout of the test and it includes a "Diode" test and "Ripple" test. The ripple reading should be less than 0.1 vac. The diode test should at least show pass or fail.