1999 Chevy Suburban voltage ok and drops with load

Tiny
ESTILO1
  • MEMBER
  • 1999 CHEVROLET SUBURBAN
  • V8
  • 2WD
  • AUTOMATIC
  • 150,000 MILES
Let me start with I have had 2 certified mechanics 1 certified electical mechanic try to fix and my self with little experice but some experince of my own.
any ways just for kicks
car voltage meter on dash began to flucate from 14volt-12s with load ac/lights/radio, and put in revers
had battery and alternator checked at local parts store with meter said batt looked alittle low but was good drove about 5 miles turned off while I went in to store then would not start.
battery origanally had burnt cell so replaced
i have put 3 new batterys with over recomended cca, 3 new alternator, both pos. And neg. Post new, then new pos. Cable. From dealership to startor and alternator, check ground with jumper cable from neg. Side of battery to frame to check ground, ran jumper cable from fuse box /computer to pos. On battery no change in voltage reader says replace batt. Have taken off cleaned, inspected, and even replaced grounds for kicks, which I do know by experince this perticular local part chain has sold defictive parts but common 3 of each now I have to give them alittle criedit, batt. With car off 12.6 volts.
car on 13.9-14 volts, alternator with in.1-.3 volts from battery voltage with load ac/radio/headlight/put in revers to leave 12volts some times 10-11 volts based on dash meter if I have less things on lights only / ac only/ low 13 volts almost 12s

anyways any help appricated please forgive me if I dont donate at this time please under stand I have already paid atleast 3 certified pros with no avail but if I am guided in the right direction even from others on this page I will be more than glade to donate

thanks in advance for all the help and your time in reading this long post.
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Tuesday, August 17th, 2010 AT 8:31 PM

8 Replies

Tiny
TOOOMANYTOYS
  • MEMBER
Well before spending any more money lets try taking some ground jumpers and trying them in various spots. Go from battery ground to body of truck. If no change try battery to inside vehicle maybe even to cluster ground. Try that its a cheap easy way. I have seen similiar problem one was a ground and another was an alternator. Lets go with the easier one first.
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Tuesday, August 17th, 2010 AT 8:48 PM
Tiny
RASMATAZ
  • MEMBER
Do a voltage drop tests on the cables


http://www.2carpros.com/forum/automotive_pictures/12900_c1_46.jpg




http://www.2carpros.com/forum/automotive_pictures/12900_c2_38.jpg

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Tuesday, August 17th, 2010 AT 8:59 PM
Tiny
ESTILO1
  • MEMBER
Thanks for reply
as stated above have replaced cable from bat pos. To startor, alt, and checked good on alt. And bat. Read 14.1 volt. On both ends meaning ground to pos.14.1 volt. And on bat.(Ground) to back of alt.14.1 with no load / with load ac, rear ac, headlights, radio, put in revers 10 to low 12s volt. Have tryed the jumper from bat. Ground to frame no change. Even jumper from bat. Pos. To fuse box that carrys load no change. (To check cable) what do you mean cluster ground?(Were the ground from the frame to motor block and block to body have already done that again. With no change oh and did I mention that voltage only gos down with a combanation of things on if only one on dose not go below 13.6
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Wednesday, August 18th, 2010 AT 3:49 PM
Tiny
TOOOMANYTOYS
  • MEMBER
Have you tried hooking up a battery charger and loading the system to see if the voltage still drops? Is it possiable to swap a cluster with a known good one? 1999 is a split year is it the old body style or new?
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Wednesday, August 18th, 2010 AT 8:47 PM
Tiny
ESTILO1
  • MEMBER
Hooked up charger to battary added load mantains 13.99-14? New body style this morning with car off battery had 12.4 now 12.6 maintained while off for 10 min. Dont have another cluster but these readings are from the battery with meter with load and with out load new readings w/ load 12.43 w/charger and load 14.01 w/ no load and no charger14.01 w/charger and load 15.28
thanks again.
At fuse box on drivers side in hood area 12.2 w/load
14. With out load
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Thursday, August 19th, 2010 AT 9:11 AM
Tiny
TOOOMANYTOYS
  • MEMBER
If having a charger hooked up to system helps maintain the voltage. I would have alternator checked or swap with another. Most autoparts store will load test the alternator.
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Monday, August 23rd, 2010 AT 7:29 PM
Tiny
ESTILO1
  • MEMBER
After all the head ackes chasing a ghost wire, 3 altornators, 3batterys, cables from batt-? Ive come to conclude the auto parts store has sold me a altornator that is to small for my applacation or they just suck.(The altornators) I have no accessorys to call for a larger alt. So im sure there just trying to push that alt. Dealership alt. Fixed all problems
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Tuesday, August 24th, 2010 AT 10:41 AM
Tiny
TOOOMANYTOYS
  • MEMBER
Was just about to ask what the amp rating was. Well glad your nightmare is over. Best of luck to you.
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Tuesday, August 24th, 2010 AT 3:07 PM

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