alternator charging

[86cucv]

I have an 86 m1009 and my voltgauge reads in the yellow i have new batteries and the passenger side alt rebuilt, had driver side alt checked and the rebuild shop says it's working fine. the drivers alt is only showing 12.7 volts running when hooked up on the truck and the front battery shows the same voltage as alt. the passenger alt shows about 26 volts and the back battery show 14 volt while running. and the gen 2 light stays on after starting and will go off when i give it more rpms, i'm i need of help i am lost and dont know what to do.

 

[beaubeau]

sounds like all is working. As long as you have more than 12 volts, all should be OK. Run it for a while and see if voltage stays up, or does it drop below 12 volts. Good luck, Phil

 

[86cucv]

i can run it about three days and then the front battery is dead enough that it will not help the back battery start the truck, when i got the truck everything was working for a week gauges and all and then now this.

 

[beaubeau]

Be sure all connections are good and clean and tight. Be sure both alt. are grounded good. Maybe alt. is not charging. Have someone else check it. I have an Alt. that is Over charging. Maybe we can Swap!!?? I shall change mine tomorow. One set of Batts. have been coocked already. Good thing I bought Good Gold Tops from Auto Zone, guaranteed for 3 years.

 

[lavarok]

You should be getting 14v+ across each battery when the system is operating properly.
If the driver side alt was removed and checked, then you need to verify the wiring and connections. Maybe the clip connection is gummed up.
The driver side alt feeds the 12v side of the system and your front battery, so the problem has something to do with it.

 

[86cucv]

in went out today and checked all the connections and checked both alts the driver side is still showing 12.7 volts and the passenger side is showing 14 volts, now i;m really confused on what going on with this truck.

 

[lavarok]

Take the driver side alt out and have it rechecked. It should be giving you 14v+

 

[86cucv]

does anybody know what the little wire is that goes from the postive junction block to the negative junction block on the fire wall behind the back battery or what it does

 

[86cucv]

i found out what it is and what does, so thats not my problem

 

[lavarok]

Check your Gen 1 bulb. See this link, bad bulb was the problem.

http://www.steelsoldiers.com/cucv/3...ng-problems.html?highlight=gen+light+charging

 

[86cucv]

both gen light come on when i turn the inginition on and the gen 1 light goes out after starting

 

[Timber01]

I am having the same problem with one of our brush trucks (85 M100 Had the drv side alt rebuilt and still putting out 12.4V same as measured on front battery when running. Battery lasts about 2 days driving and using headlights drains battery fast. Checked & cleaned all connections but no luck. Same symptoms exactly. There has to be an answer. Since we have 2 of these trucks, I'm swapping alternators to see if the shop screwed up when rebuilding. Will have an answer hopefully tonight.

 

[4bogginchevys]

combined voltage checked at alt #2 should be no less than 28v

 

[Screamin' Metal]

Also let me add......clean all you connections at your Alt.'s and at the Batt.'s. After that, clean and check connections @ junction blocks on firewall behind rear battery. Make sure your belts are tight.
Make sure you turn off your service light switch and civ. light switch....(theres a dome light below the dash that'll draw down a battery, if left on.....I had a handfull of those to happen)

These trucks sit the majority of their lives at the motorpool, sitting....when they're sold.....they suffer from a lot of corrosion on the terminals.....you gotta do alot of cleaning.

 

[Timber01]

Swapping the alternator fixed everything! The shop that "rebuilt" the alternator is getting it back to do over again