battery question

[johnsr]

i am still trying to learn how this 24v 12v system works, so please for give this question. i have been having some start problems with my m1028. i have had to replace both batterys. the one by the fire wall was bad, so i just replaced the pair. ran fine for a few weeks. started geting harder and harder to start, so i thought i would top off both batterys. the one by the fire wall was all but dead, charged up fine. the other battey was at about a 90% charge. my batterys should both be fully chaged after driving the truck around for a few hours? also the gen1 and gen 2 lights have not come on. i bull both altanators and am having them test. bet the one on the passengerside is bad.


my question was both batterys should be chared evenly.

the pasenger side alt was bad no out put.so my fix was to put my good alt on the pasengerside, and found a 100 amp alt for a bus for the driverside(alt is a case ground). runs grate, and chages fine.

 

[Westech]

well the one on the right side charges your rear battery. So if that is dead its not going to charge 24V and poof.. no start. Kinda makes sense to me.. have a bad alt and the battery goes dead.. I just sayin...

 

[Barrman]

I don't understand the question. As stated above, the passenger side alternator is the ALT 2 and charges the rear battery. Which matches the other side up as ALT 1 and the front battery charger. Since you have it being worked on, have them do a complete rebuild and make sure they keep it isolated ground. If you get sparks when you hook things up, then it is not isolated ground and should go back to the shop until they get it correct. Your problem was most likely a bad Diode Trio which is about $5.00 to buy.

download and read the -20 manual for the truck. It walks you through most problems with the truck.

 

[dstang97]

Do both gen 1 and 2 flash when you turn the key? If not replace/ clean bulbs. you need those to work or they will not charge your battery

 

[johnsr]

gen 2 light dose not come on at all, the bulb is good. with a volt metter i am getting 27v on alt 2.but my back battery seems not to be charging. i did check the gen 2 relay and it is good.

 

[Warthog]

Again..... there is an easy check to see if the inside wiring is working properly.

1. Make any electrical check with fully charged and load tested batteries.
2. Remove the two pronged plugs from the alternators. This is what you will be testing
3. With the key off - the small RED wire (PIN 2) on the drivers side will have 12v
4. With the key off - the small RED wire (PIN2) on the passenger side will have 24v
5. The small brown wires will not have any voltage.
6. Turn the key to run but do not start the engine
7. The small brown wire (PIN1) on the drivers side should now show 12v
8. The small brown wire (PIN1) on the passengers side should now show 24v

If you do not have the above readings then there is something wrong with the inside alternator circuits. You will have to use the Tech Manuals to troubleshoot the circuit.

The majority of the time, the GEN2 circuit is not working because the very bottom 24v fuse is missing or burnt out.

P.S. - Please label your NEW "non-isolated ground" alternator so you do not injure someone when they are working on it and assume it is isolated.

 

[johnsr]

voltage is 12v on the driverside and 24 volt on the passenger side. 24v fuse is there and good. the new alt is just there for a quike fix till i can aford a rebuild on the old alt. if it helps any my volt gauge is getting 24v to it.

 

[Warthog]

voltage is 12v on the driverside and 24 volt on the passenger side. 24v fuse is there and good. the new alt is just there for a quike fix till i can aford a rebuild on the old alt. if it helps any my volt gauge is getting 24v to it.

Where are you readin the voltage? At the plug like to posted above or at the positive terminal on the alternator or at the battery itself?

Is the truck running or off? If off you are just reading battery voltage.

When the truck is running you should see ~14.5v on the driver side and ~29 on the passenger side.

 

[johnsr]

i followed the post step by step.

 

[JDToumanian]

gen 2 light does not come on at all, the bulb is good

The gen2 light MUST come on when you turn the ignition on and go out when you start the truck.... If not, you are not charging.

There is a 99% chance that your gen2 alternator is bad, my M1009 did the exact same thing as yours and replacing my gen2 alt. fixed it.

Regards,
Jon

 

[johnsr]

gen 2 tested good off the truck. brought it to a shop for testing. im woundering if it could be the diode for gen 2?

 

[johnsr]

i have had the alt tested off the truck at on of the shops in town, it tested good.

 

[JDToumanian]

Oh.... Well, I'd check fuses, and there's a few relays that could be bad too... Time to go through the troubleshooting manual!

 

[johnsr]

fuse is good and so is the relay for gen 2, and the volt gauge.

 

[johnsr]

when testing the gen 2 diode what should my metter read?

 

[camerodad]

Where is the 24 Volt Fuse, I am Having trouble with my GEN #2 Loight not working, I replaced the Bulb, Checked all the Connections on the ALT???

 

[johnsr]

verry bottom of your fuse box. it is a 10 amp fuse.

 

[johnsr]

ok, i had a shop check my gen 2 diode, and its good. so i am thinking that it my be a bad ground at the relay???????? or the printed circit on the back of my dash cluster?????any thoughts on this?

 

[Barrman]

Have you followed the steps Warthog outlined in post #6 above? What did you find?

 

[johnsr]

yes, i got 12v won the driverside and 24v on the passengerside. i swaped the gen 1 bulb with the gen 2 and i still dont have a gen 2 light. i alsow swaped the gen 2 relay with the volt gauge relay. still nothing. gen 2 test good off the truck. im about ready to pay som one to fix it for me.......... this is starting to stess me out( that why i worked on the rear diff today).