alternator charges sometimes

skoal777 · Dec 24, 2012

When I start my 97 ranger it changes sometimes but you never know when it will. Sometimes when I start the truck it will have the battery light on and will not charge but sometimes will start chargeing as I go down the road but sometimes it will not charge for a day or two. Other times it will charge normally and everything is fine. This only happens when I start the truck so I'm not sure y this is happening. The alternator is new and so is the battery. I also cleaned the battery termanels and the wires going to them. This all started happening after I changedthe clutch and starter. Any ideas would be very helpfull. Thank you!

adsm08 · Dec 24, 2012

Got a volt meter?

Hook it up to the battery, start the engine, and then by hand pull the throttle wide open for 3 seconds and let it go. See it is starts charging on it's own.

kimcrwbr1 · Dec 24, 2012

It could be a grounding issue with the alternator it never hurts to add a ground wire 10-12g from the alternator chassis to the neg battery terminal. Many people do it as an upgrade when adding a high amp alternator. Sand all the grounds you can find metal to metal and cleann all the connectors with electrical cleaner and use dielectric grease when putting them back together. Somtimes wires and cables will corrode under the insulator where it looks good. Bend all the wires and cables looking for a weak spot and replace it if necessary. Intermittent faults can be a bitch make sure the belt is good and tight and if you dont know how old it is just change them as PM. The tech library will tell you how to do a proper load/noload test and you can troubleshoot from there. Make sure the battery is fully charged, belt and wires are up to snuff then do the load no load tests. All you need is a VOM print out the procedures. One bad component can destroy the other two (battery,alternator,voltage regulator) fairly quick make sure it is working correct it can get expensive. The computer and ignition need a steady voltage for peak performance.

kunar · Dec 24, 2012

Are you sure its really not charging or could it be a fault in the wiring to the light or gauge?

skoal777 · Dec 24, 2012

Yes I'm sure that it isn't chargeing cause the lights are all dim and the blower for the heater is not going as fast as it usually does. I don't have to use a volt meter cause your alternator should be warm if it is charging but when the lights are dim and the battery light is on the alternator is cold as it is outside right now its 33 degrees out

naford · Dec 25, 2012

I would agree thats it's probably a ground. When I ws in class we had a Crown Vic that had a similar problem. When the car was running we felt the wires comming off the battery. The smaller of the 2 was hot the bigger one was cold. When loking around we found that a ground from the firewall to the motor was broken. After that was fixed the problem was cured. What I suspect happened is that when you were working on th truck you disturbed one of the grounds. It might look good but the strands of wire are broken near the ends. Another thing you could try is to take a piece of wire with just the ends stripped away and go from ground to ground just touching across the ground adn see if you notice a change. Obviously the truck has to be running and the problem present.

CarsonChris · Dec 31, 2012

My 99F-350 goes through an alternator every couple of years. It does the same thing. Starts working intermittently. It's on a duel battery system. I've been told to replace both batteries at the same time. One usually draws the other one down and causes the alternator to overwork.

PanamaExpat · Dec 31, 2012

The alternator on my diesel ride is a Bosch and it started doing the same thing when the brushes were getting to that point. Now it doesn't charge at all. Since I am a lazy old fart I just charge it up before I drive it and it is good for a couple of days. Good thing mechanical pump driven diesels don't need electricity to run. Just don't stay out after dark.

Andy D · Dec 31, 2012

Hey PE \. Regarding the Bosch alternator. If it is like the alts in my BMWs, lt has a regulator / brush pack that is on by 2 screws and can be removed in place. The regulator is widely available, New brushes, can be soldered in. are hardware store items. Happy New Year

scooter · Dec 31, 2012

I worked in a starter/alt shop for a couple months in '02. Try pouring water in it while its running. Sometimes the brushes get stuck or glazed. I usually shoot a lil WD40 in after that tho.

Works more often than you would believe.

UrbanRedneckKid · Dec 31, 2012

Any time my battery light comes on or has flickered, it was because the grey 1-wire connector had a broken clip, or bad connection.

A rolled up piece of cardboard wedged between the connector and the body of the alternator is a good free fix.

Sent from my PG86100 using Tapatalk 2

doorgunner · Jan 1, 2013

check/clean the alternator fuse & the copper contacts that it plugs into (with your wife's fingernail emory-board....sometimes the contacts get glazed over & cause intermittent charging

alternator charges sometimes

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