fwfjack

My alternator is putting out 12.8v and my battery is good. (I can externally charge the battery and run short trips on it alone!).
Why is my alt output not getting to my batt?

Feeling kind of dumb right now...

arjeeper

Are you reading the alternator power at the alternator posts or at the point they reach the battery. Possible the alt is putting it out but a bad cable or something is preventing it reaching the battery.

fwfjack

12.3v DC right at the cable (unplugged) connection on Alt.
I just bought it NEW from dealer yesterday.

ronjenx

If you are saying you are checking it with the cable from alternator to battery disconnected, that will cause the PCM to shut off the field, resulting in your meter reading just battery voltage.

fwfjack

I think im getting the alternator output. The only thing connectoed to the alt is the belt and the ground.

I inplugged the output cable and am testing the prongs on the alt.

ronjenx

Like I said, if the positive cable is disconnected from the alternator, the PCM will shut off the generator field. With the field shut off, it will not generate. The 12.3 volts you are getting at the alternator post looks to me to be battery voltage.

fwfjack

OK. when I plug the alt back in, where do put my probes to check its output to see if its getting to the battery?

charged batt again, connected alt and started: got 12.46v at batt terminals. voltage slowly drops...

I'm feeling a bit stupid here.... is there a fuse or relay or something between the alt and the batt that needs replacing?

33 williys 77

yes there is a inline fuse sitting close to your + post on the battery

ronjenx

Check for codes with a code reader.
Check all connections at the alternator, battery, and ground points for being clean, and secure.

Check the positive wire at the disconnected alternator end of it to see if it reads the battery voltage. That will tell you if the wire and fuseable link are OK.

Reconnect it to the alternator. Start the engine.
Read voltage at the alternator lug, and at the positive battery terminal.
If both read just battery voltage, the alternator isn't putting out.

That could be a bad connection, alternator, PCM, or TIPM.

33 williys 77

If the Alternator is working the battery voltage should read somewhere between 13.8 to 14.2 volts