Before I turn it on
 

Being new to this stuff, I am curious. When you turn my key and before the 'wait to start' light comes on, there is a 'thump' sound. It just started this week. I was wondering if this is normal, but like I said, just recently started. Thanks.

Doesn't sound familiar. Sounds to me like they have somethin hooked up to run in the accessory mode. Can you tell what part of the truck it's comin from.

It comes from the engine area. Like I said, just started making the sound earlier this week. I did install new rotors, brake pads and driver hub assembly last weekend. Any thoughts it might have to do with that? Thanks.

it is possibly something in the heat/air system, only thing i can think of that would make a clunk when u turn the key to the onn position on a 24v. good luck with it and keep us posted

Appreciate the help. I will try to see what I can figure out. Will let you know...

Sounds like air/AC to me as well. Mine will make a clunk a few minutes AFTER shutting down, even if i'm not using any air.

Start pullin fuses one at a time and turn the key. When it doesn't make the noise your on your way to findin it.

it could have something to do with your brake system under the hood. may have something to do with your abs system too. could be your stock lift pump but since you say it is before the wait to start light is on probably not. mine makes a noise for a second, its sounds like its somethin to do with the brake system, sounds like an electric motor. (but its not the lift pump)

I hope to be leaning toward the ABS. I replaced all that stuff last weekend. That is when the noise started. Is this common? Did I do something wrong? The brakes work, sometimes grab a bit on that side (driver)... Suggestions?

i dont think it could be from replacing them. i dont know to much about the brake system on these truck, there a little different form the 12v. I just know mine makes a noise and its around the master cylinder somewhere. have somebody turn the key on and off why you look under the hood and see if you can figure out where it is coming from. And the brakes.. did you replace the brake hoses that bolt on to the calipers? they will collapse and not let the brakes release very well (or sometimes not at all) but if you bought reman. calipers from oriellys (or anywhere for that matter) they may be bad. i went through three on the drivers side and two on the passanger side in three years on my old truck dodge. mine pulled to the right but i thought it was the brake hose, replaced it but it ended up being the caliper so i replaced it too. I had lifetime warranties on my calipers, that was nice:U: