521 charging

[dbuzz77]

the ign light came on today, the battery voltage is going lower, so i assume we're not charging. i thought it was a loose ground on the alt, but it wasn't. I get battery voltage (going lower) on the w/b and y wires at the regulator so i assume the alt is not charging. if the alt was working , the voltage at the regulator would be 13.5 or 14v, am i correct? i need to rebuild the alt? thanks

[jefe de jefes]

You have a voltage gauge in your ride?Sounds about right. Buy a new one. They aren't that much.

[datzenmike]

the ign light came on today, the battery voltage is going lower, so i assume we're not charging. i thought it was a loose ground on the alt, but it wasn't. I get battery voltage (going lower) on the w/b and y wires at the regulator so i assume the alt is not charging. if the alt was working , the voltage at the regulator would be 13.5 or 14v, am i correct? i need to rebuild the alt? thanks

 

The external regulator tells the alternator to charge and how much. Don't assume the alt is bad.

 

Is the belt tight?

Battery cables tight

Ground wire from battery to head tight and clean?

* Regulator won't work if it is not grounded to the body or loose.

[dbuzz77]

i am assuming the alt is bad because the volts at the regulator are down. if the alt was working, wouldn't i see 14v at the reg? (belts and posts tight)

[dbuzz77]

i went to check the engine ground, looks good. the headlights won't come on, just the park lights.

[datzenmike]

i am assuming the alt is bad because the volts at the regulator are down. if the alt was working, wouldn't i see 14v at the reg? (belts and posts tight)

 

The alternator could be bad, yes. But the regulator detects low voltage and tell the alt to increase the charge. If it's not working the alt is just along for the ride.

[dbuzz77]

what's next? i wonder why the headlights don't work.

[datzenmike]

Parking lights but no headlights.... check the fuse box for good connection or blown fuse.

[dbuzz77]

found the fuse, bad connection for the headlights. took the cover off the regulator and manually operated the relays, no change to the battery voltage (with the truck running). i would guess it's the alt then?

[dat521gatherer]

one other thing to do for process of illimination is to clean the ground wires that bolt to the voltage reg.

[dbuzz77]

had the alt tested, no output. the guy said a strap was broken inside.

[ggzilla]

When you get the new one installed, test the output. At 1200 RPM is should be between 13.5 to 15.0 volts. No higher or it will burn something out in time. No lower or it won't charge the battery properly.

 

The V out is controlled by the regulator.

 

If you hotwire the F terminal of the alternator (briefly) it should put out more than 15V.

[dbuzz77]

new alt , all is good. a jumper was broken on the rotor. thanks everyone