1991 1/2 Ton Diesel Will Not Charge

[iamhere300]

I have a 1991 1/2 ton diesel GMC truck, we use it on the Fire Department for a brush truck. 2wd. It has stopped charging. We pulled the alternator, and the parts store checked it on their machine, and it showed to be charging.

 

Re-installed, it does not charge. Checked connections, they appear fine, clean and tight.

 

Ideas?

[jro909]

batterys...a shot battery won't take a charge

[iamhere300]

batterys...a shot battery won't take a charge

 

 

Charged the batteries with a battery charger, they held the charge, started it a number of times, but we took it out the other night an soon the lights got dim, the voltmeter went down as the lights got dimmer.

 

Probably over the course of 3 weeks started it 10 times or more checking it.

[FarmerDave]

Corrosion on battery terminals??

[iamhere300]

Corrosion on battery terminals??

 

 

Clean as a whistle. Which leads one to ask just how clean is a whistle, and why, but that is a topic for another board.

 

Thanks, we have checked the common stuff, just can't seem to get this.

 

Can someone tell me what the black and white wire go to on the starter? What is their purpose?