M35A2 not charging well?

[Lax]

Hi guys, I know this has been touched on before somewhere. My M35 shows at the gauge that it may not be charging. It has always held right at the tick in the green perfectly. Then it started to get in the yellow. I did some checking and found one of the headlight wires had worn through and was shorting on the frame. I fixed that and all was well for a while but now the gauge is back in the yellow. All lights are working and I have charged the batteries to 100%. There does not seem to be any power lose as the truck starts fine and the lights are bright. I can not find any arching or loose wires. I did notice the belts to the alternator are a "little loose" I can move the belts up and down about 3/4" in the middle of the span from the pulleys. Any thoughts? All I have is a inexpensive volt/amp meter for electronic tools. Thanks for your help.

 

[Lax]

Would the gods smile on me and make it that easy!!???

 

[jollygreen]

check yalls grounds i think there are 4, i know theres one on the radiator one on the engine one on the tranny and of course the batt box i think thats all

 

[Lax]

Good idea. Do those grounds go directly from the alternator to those areas? sorry for the dumb questions..

 

[BKubu]

Did the previous owner have any problems with it? My recommendation would be to first contact the seller to see if he can offer any advice.

 

[jollygreen]

no they dont come off the alt they from the talked about to the frame i think

 

[avengeusa]

OK, here you go, number one, do not rely on the gage, it may be off....

use a volt meter and measure battery voltage across bot batteries while the engine is running

it should read substantially more than 24 volts, 26.5-28 or so

If not you need to check the wires on the alternator, the large one goes from the charge terminal on the alternator to the large post on the starter solenoid on the starter, check for shorts to grounds and make sure the wire is not having a break in it, you will use an ohm meter for this

then check the smaller wire on the alternator, it should have battery voltage on it only when the main power switch on the dash is turned on

if it has batt power, then the problem is inside of the alternator, most likely the regulator, they are known for going out





if you are not getting