Battery Draw

[DGrun22]

i have a '99 silverado 5.3l e-cab z71, i think i have a draw on the battery, alternator is putting out good volt. lights dont dim or flickr even with blower motor on, but after over night sit extened cranking to start, but before i started getting out the meter, does anyone know of a common draw on these trucks, and if not what kind of amps should i get when the truck goes to sleep?

[bill190]

Are you saying...

 

A. It takes a lot of cranking in the morning to start, but it is cranking with a normal sound and speed?

 

Or...

 

B. The battery is quite weak in the morning and it cranks slower than it should and you need to jump start it or charge the battery before you can get it started?

[DGrun22]

slow to crank

[bill190]

OK, then what you can do is of course charge your battery with a battery charger until you find the problem.

 

Then (with the engine and ignition off) disconnect a battery terminal and connect an amp meter between the battery terminal and the cable. Then remove one fuse at a time and see if that reduces the amperage draw. Do this with all fuses one at a time and keep track of which fuses make a change in the amperage draw and how much. Replace each fuse before testing the next fuse.

 

Also before testing, disconnect or remove the light bulb for the under hood lighting if you have that. That would show an amperage draw. And have someone hold in the door button so the inside lights are not on.

 

A possible suspect would be any electrical things you have added on to the vehicle, so check those things as well.

[DGrun22]

yeah i know how to do the draw test i work for benz, but we have common things like our c-class the seat control modules like to draw, but i went to get some food and just noticed after i shut the truck off i hit the brakes and the trailer brake module still has power i didnt wire came with truck when i bought it used, so im going to dissconnect the battery tonight and take it up to my shop tomorrow for maitnance and check the draw

[DGrun22]

sorry dont mean to sound like a dick head and any amount of help is appreciated

[bill190]

BELIEVE me, I am quite happy if you know how to do the draw test and I don't need to explain it further!