1998 Chevy Astro charging problem

Tiny
HAGGLUNDBV206
  • MEMBER
  • 1998 CHEVROLET TRUCK
I am having trouble with my 98 astro keeping the battery charged. I have replaced the alternator twice and it has a new battery as well. Weird thing about it is the battery will charge most of the time when its at idle, but voltage drops when there is a load on the motor. On the highway the drop is down to 10 to 12 volts and killing the motor. I was suspicious of the fuel pump. Could a bad pump cause this type of problem? I can hear the pump go up and down at the same time the voltage changes. Seems to me like the battery should charge more at highway speed than at idle. But it's opposite.I really don't even know where to start.
Do you
have the same problem?
Yes
No
Saturday, April 15th, 2006 AT 12:05 AM

8 Replies

Tiny
LOSONE
  • MEMBER
Check all of the grounds battery to engine, engine to body and battery to frame. REMOVE them all and clean the connection. I think that will solve the problem. Good luck
Was this
answer
helpful?
Yes
No
Saturday, April 15th, 2006 AT 6:15 PM
Tiny
HAGGLUNDBV206
  • MEMBER
Well so far what I've done is taken off and cleaned all the grounds on the entire van with a dremel. I did find 1 ring terminal broken on the t-stat bolt and replaced it. All of the contacts were definitely corroded. I think I am on the right track looking for a bad ground, but nothing I have done has made any change. The guage will still go up and down and also the headlights will dim. Running out of things to check. Is there something I could be missing? Grounds found so far are 2 to the block atleast 7 in the engine compartment to the body and several on the frame. All of the wires looked ok, I didn't see any obvious breaks, only the connections were corroded
Was this
answer
helpful?
Yes
No
Friday, April 21st, 2006 AT 10:01 PM
Tiny
LOSONE
  • MEMBER
Good job on the grounds. The next trick is to check the voltage output across the battery terminals with the engine running. Turn on what every you do to cause the problem and measure the voltage. Under all conditions the voltage should read between 13.5 and 14.7 volts STEADY-NOT JUMPING. Next put the meter on the ac scale and check across the battery. The ac volts should be less tan 5v ac. If either are out of the zone replace the alternator.

You can get a good digital volts meter anywhere for less than $10.00 and is a must for any checks. Let me know.
Was this
answer
helpful?
Yes
No
Saturday, April 22nd, 2006 AT 8:03 AM
Tiny
HAGGLUNDBV206
  • MEMBER
Well I checked the ac volts are going all the way up to 7 with my fluke 87 meter, the dc volts are bouncing from 11.5 to 14. While idleing with no accessories on. I have replaced the alternator twice with no change I also changed the battery just in case. After I put the first alternator in with no change I took it out and had shuck's test it. Tested ok, but I replaced it anyway with a better one. When the voltage jumps around there aren't any electical accessories on just the fuel pump which I can hear spin slower and faster as the voltage changes. When I'm driving with the lights on it's the same story except I can see the light dim and hear the pump change. I think I'm going to yank thet alternator out and have shcuck's test it just incase. I have had lots of bad new parts before but usually not 2 in a row.I really appreciate all of your help. I'll let you know what schuck's says about this alternator
Was this
answer
helpful?
Yes
No
Saturday, April 22nd, 2006 AT 4:37 PM
Tiny
LOSONE
  • MEMBER
That is the story on ALL discount parts houses. The parts are rebuilt in Mexico or China and sometimes they are just cleaned and sold. For important parts I use NAPA or the dealer. The only thing I buy from those stores is what I can pour out of a bottle or can.

I still feel there might be a loose connection problem. Check the little box on the fire wall that the small red wire from the battery goes. Make sure the connections are good. Also check the battery lead to the under hood fuse box.
Was this
answer
helpful?
Yes
No
-1
Saturday, April 22nd, 2006 AT 6:36 PM
Tiny
HAGGLUNDBV206
  • MEMBER
OK here is the latest I've done. I took the alternator out and had schuck's test it, they say it's ok, but I wonder how good their test is. When I pulled the alternator I notices the little red wire that goes to the plug was severed, what is the purpose of this wire. I assume it just goes to the voltage sensor or something. Right now I am trying to reterminate that wire, what a pain that is. I will probably have to get a connector at the junk yard to splice in because this one is severed right ate the plug. I also checked the little wire that goes to the fuse box. I even dissassembled the fuse box to look for anything in there. One thing I did notice was the positive terminal on the battery wasn't making as good of connection as it should have been, the little rubber cover was covering some of the connection area. Sidepost terminal is what I'm refering to. I cut off the excess rubber and made no change. Could the little wire on the alternator make any difference?
Was this
answer
helpful?
Yes
No
Sunday, April 23rd, 2006 AT 9:04 PM
Tiny
LOSONE
  • MEMBER
That is your main wire that supplies activating power to the alternator. You can buy the connector at a parts house with one of those fix-it racks. That IS your problem. Good Luckr
Was this
answer
helpful?
Yes
No
Monday, April 24th, 2006 AT 7:24 AM
Tiny
HAGGLUNDBV206
  • MEMBER
Yep that wire is important, I opened up the connector and soldered the wire back onto it and it's working perfect. Thanks for all the help
Was this
answer
helpful?
Yes
No
Tuesday, April 25th, 2006 AT 2:18 PM

Please login or register to post a reply.

Recommended Guides