Alternator question

Battery died on my 96 2.4, and I think the problem is the alternator. With the engine running I am only reading about 1.8 volts on the battery lug on the alternator. Is that a bad alternator or an "unexcited" alternator? Also, battery voltage goes up very slightly with engine started, but drops quickly if the engine is revved or if the headlights are turned on.

I already put a new battery and terminals on it, ran great until the voltage tanked. Am I missing something or does this sound like a dead alternator? thanks

 

Are you measuring 1.8v from the large wire on the alternator to a ground?

What is the voltage from positive to negative battery terminals while running.

 

Voltage with engine running on large wire to ground is less than 2 volts.
Voltage at battery was 12.3 at rest, went slowly up to about 13.4 with engine running. Dropped below 12.3 if engine revved or lights were turned on.

 

Change alternator, or rebuild. Up to you.

 

Thanks, I'm thinking about upgrading to a 105A GM unit, seems to be a popular option.

 

Make sure you upgrade to beefier wiring if you go that route

 

check to following fuses first. The 120 amp fused link in the engine compartment relay panel. The ATL-S fuse (7.5 A), IGN (7.5A), Gauge (10A). They all either feed or protect the alternator/regulator.

 

6ga off the alternator to the battery should work. It's a hybrid truck, the '83 harness is maybe an 8ga at best, or a thick cased 10ga that was only meant for 40A. The smaller wire can still go to the cab, the new 6ga will handle the main load directly to the battery.

 

Good ideas Glamisman, but I'm not sure the '83 truck that the '96 2.4l in it has those fuses. I will check.

 

The wire on back of alt should have battery voltage. If it doesn't the fuse is probably bad.

 

All fuses were good. 105A alternator is installed and working great.