Charging System erratic. Please help.

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Feb 19, 2003 | 01:17 PM

pascualjr

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Intermediate

Joined: May 2002

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From: Mililani HI

Charging System erratic. Please help.

My '89 Coupe's charging system is erratic and I can't figure it out. The battery is less than a year old and the alternator (CS130) is also less than a year old. The battery warning light in the center console comes on and the voltage reading in the instrument panel reads 9.5 to 11.3 volts. If I increase the idle, the batt. warning light goes off but the voltage is 11.5 max. Then, with no warning, The voltage display would go up to 13.9-14.1 volts and the batt. warning light would go off and everything seems normal. I'd turn it off and re-start it and it would go into the low voltage/batt. warning light on condition. It seems to be an intermittent continuity condition but I don't know where to start. Any advice would be much appreciated.

Thanks in advance.

By the way, I tried to do a search on the forum but came up empty.

Feb 19, 2003 | 01:50 PM

don hall

Safety Car

Joined: Aug 2002

Posts: 3,842

Likes: 230

From: SANTA CRUZ CA

Re: Charging System erratic. Please help. (pascualjr)

You may have loose wiring, but more likely your alternator and/or regulator are faulty. Ground out your alternator to see if you have max output. If there is no change, your alternator needs to be replaced. If your alternator gage shows max output, your regulator is faulty. Your alternator may still be under warranty. If not, pull the alternator and take it to an auto electric shop. It can be tested in just a few minutes. I'm sure you are aware that your voltage output should read 12V+ static, and 14V+ dynamic with a fully charged batt, and a properly operating alternator.

Feb 19, 2003 | 02:36 PM

Sharkracer

Instructor

Joined: Oct 1999

Posts: 153

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From: Cartersville GA

Re: Charging System erratic. Please help. (pascualjr)

Sounds similar to a problem we diagnosed on a Freightliner at work the other day. Make sure the belt is tight. Push on the top of the belt to see how much slack there is. Push down on the tensioner to see how easily you can move it. A loose belt may or may not squeal. Check the simple free things first!!!
:chevy

Feb 19, 2003 | 02:45 PM

pascualjr

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Joined: May 2002

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From: Mililani HI

Re: Charging System erratic. Please help. (Sharkracer)

Belt tension was checked. It's not slipping.

Also, I replaced the CS130 with a new CS144 and the symptoms are still there. The battery seems good - 12.25 volts.

Feb 19, 2003 | 06:36 PM

VetNutJim

Safety Car

Joined: May 1999

Posts: 3,651

Likes: 5

From: Atlantis

Cruise-In I Veteran

Re: Charging System erratic. Please help. (pascualjr)

Check ALL your connectors. Alternator output. Battery Positive and battery negative.

"Could" be internal to the battery.

Pull your wifes car up and connect the jumper cables between the two.

Start your Vette and observe the symptom. If it's gone or minimized it's probably a intermittent cell connector inside the battery.

If the problem persist:

Remove the battery.
Check the ground strap that is connected to the frame behind the battery.
Check the grounds up at the left front frame rail.
Check the STARTER connections.

Out of airspeed and ideas for right now.
Good luck with it.

Feb 19, 2003 | 07:39 PM

jfb

Team Owner

Joined: Mar 2001

Posts: 54,124

Likes: 30

From: Cincinnati, Oh USA

Re: Charging System erratic. Please help. (pascualjr)

You have an intermittent connection from your alternator. Check for tight crimp on both ends of the alternator output wire (back of alternator to jumper terminal by the battery) and clean lugs and tighten nuts. Pull on both ends of the fusible link to test for good connections. Remove battery cables (neg first) and clean lugs and battery terminals and replace (neg last). Unplug the connector on the alternator and see if the lugs on the connector are bright and grasp the alternator connector blades.

Feb 19, 2003 | 07:43 PM

pascualjr

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Joined: May 2002

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From: Mililani HI

Re: Charging System erratic. Please help. (jfb)

I've done all the items you suggested. Sometimes on initial startup all seem to be fine. but then after running for more than a couple of minutes the battery light comes on and the voltage drops from 13.7-14.0 down to 11.3-11.5 or lower.
I then checked the voltage of the wiring from the alternator to ground with the ignition switch in the RUN position:
Alternator 'Bat' lug to ground = 12.00 volts.
Wire Harness from Alternator:
Red to ground = 12.00 volts
Dk Blue to ground = 12.00 volts
Brown to ground = 11.80 volts

Across the Battery terminals = 12.00 volts

Could there be something wrong with the Brown wire? That's the one that leads to the battery light and Gage fuse (fuse was o.k.)

I'm still stumped. Thanks, again, for all your help and the rest of CF!

Feb 21, 2003 | 02:22 PM

pascualjr

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From: Mililani HI

Re: Charging System erratic. Please help. (pascualjr)

o.k., this is one for the records! I finally resolved the problem - It was the alternator after all! I went back to my mechanic and picked up another remanufactured CS130 (I returned the "new" CS144 and the other "new" CS130) and everything works! I decided not to get another CS144 because of the hassle of filing down the mounting tab just to find out that the CS144 is defective. Anyway, THANKS again to the CF for all the feedback!

Jr. Pascual :party: