Chevy Venture - Beginning to move after starting the van

I have a 97 Chevy Venture 121K. Only happens after I start the van put it in drive and start to move. I hear a sound that seems to be coming from the driver front side - sounds like anti lock brakes activating (that sprockety kind of sound) - I will hear about three or four of those clicks - the lights will dim - everything electric will just be on the verge of shutting off for a split second. The sound stops - everything electrical comes back up to full power and it will not do it again until I shut the van off and start it. As soon as I start the van (warm or cold) put it in drive and go to take of - three/four clicks - power dims - comes back up and all is fine. Nothing at stoplights - put the brakes on - lights don’t dim - no power fluctuations during start stop driving at night.

What should I look for or test or ???

Thx

You say it sounds like the ABS activating? The ABS runs a self check every time you start the vehicle and accelerate over 3 MPH. Is it possible you just started noticing this? Like one day you started the car with the radio off and … Bingo…What the heck is that noise.

Well - if it does a self check every time the vehicle is started and it goes over three mile per hour - that would explain the noise then. Because that’s what it sounds like - the ABS activating - it does about 3-4 “clicks” and stops. So that is normal then - that is a good thing BUT the part that gets me is that during the time it does that self check - the entire electric system almost goes dead - the ABS clicking at start up stops and all the electrics come back to full power. It doesn’t drain the power like that is the ABS activates on slippery roads - all the lights stay up - blower fan stays up - radio etc.
Does that make sense?