99 Suburban help

Any mechanics here?

I was driving the other day on the freeway, when my lights flickered, the anti lock light came on and the car breaked suddenly, very quickly.

Took it to the shop, they looked into the front right speed sensor, but saw no obvious problems.

The following week i noticed my voltage meter was dropping and got a slugish start, then that grinding noise upon starting when a battery gets low.

Hooked up the battery to the charger, woulnt charge it was so dead. Bought a new battery $$$, noticed to voltage guage was looking good again. Drove it today, and noticed it dropping again, slowly. Parked it and noticed the positive cable lead was kinda hot? At some point it must have got really hot, cause when i swaped batteries, i noticed the hardware that holds the positive lead was ill shaped, as if it got too hot at some point. When? i dont know. bought this used a couple years ago.

Is my alternator dead?

Also noticed the security light is on sometimes when i drive, this has been going on since weve had it.

otherwise runs great? 

Any help, id like to go into the shop with some knowledge so i dont get screwed...

Thanks in advance!

I am a mechanic, here is what you need to check.

Get a good volt meter and check output volts at the red stud on the back of the alternator while truck is running. Should read between 14 and 14.5 Volta with a new battery.
Next change volt meter to ohm reading and check continuity from the negative side of the battery to the engine block should read 00.0 ohms if it's any higher start checking body and chassis grounds if they get too corroded or loose strange things can start happening.
That's a good place to start, if you need help shoot me a pm with a phone number and we will fix this booger.


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Hot wires almost always means too much resistance = coroded conections, bad ground somewhere, maybe even a pinched or nicked wire.  Do what kayak James says and check your resistance to ground.

ok, thanks. whats a good volt meter?

Just get a decent multimeter.  If u don't need it all the time there's no reason to spend over 100$.  Don't get the cheapest either. U could probably pick one up at kragen or radioshack. I use fluke meters for work, but they ain't cheap!

Craftsman brand are repackaged flukes most of the time. Sears has a good selection in the tools department. Where you located maybe you could borrow mine?


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Im in santa cruz?

Yeah I can't spend too much on it.

Im wondering if this has something to do with the 7 pin towing set up I had installed a while back? I remember him struggling with the ground wire, but the problem just started fairly recently, I had 7 pin install done a year or so ago...

Not likely a problem with the tow package,
Sc too far for me to drive today,
Home depot has some inexpensive meters, that's kinda the first step here need to know what's going on. You can still do a visual on connection at the alternator and the grounds. Those have a extra hot stud next to the alternator for jump starting  make sure it's not touching ground.


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no worries, ill get one then report back with the results.

On the power + cables there should be 2 at the + post... In between them there is a lead spacer that gets corroded often when the battery starts to leak a bit. Pull it a bit (cables) if they move around, replace spacer and clean or replace the cables. Real common problem I see a lot. Also replace the battery if you see corrosion in that area or it will happen again... Good luck (just saw you replaced battery already) Ps... You will have to pull hard to get the 2 cables apart by the way. a small screw driver works to remove the lead spacer....

ok, this battery is brand new, just got it 2 days ago. I did scrub up all the parts with battery cleaner stuff, then put the protectant back on everything when i put it back together... there was some corrosion at that time

Did you separate and remove the spacer? that is where the corrosion gets real bad (assuming you have the 2 cables at + terminal
 
The outer cable feeds computer and alternator. inner one feeds starter. this is why it freaks out

Don't some of the auto supply places check your battery and or charging system for free?  This way you would not have to buy a voltmeter that you may never use again.............just a thought..

If the altenator check doesn't produce any conclusive results try swapping out the battery cables (might wanna do it anyway if one was hot and melting). 

Ill check on the free check. Ill go snap some pics of the setup. The positive wires do look a bit worn.