I have a 94 blazer 5.7L, alternator stopped charging battery all of a sudden, I took alternator to orielly to bench test it and it passed. The setup on this vehicle is post on alternator goes to the battery then the plug on the back has one wire in it that looks factory. I get nothing from either spot but I'm using a test light not a meter as it is at work, any how the plug gives nothing and if I disconnect the wire to the battery on alternator I get nothing. I'm lost here the cable going to battery don't have a fuse nothing just straight cable. Any help would be greatly appreciated.

 

So this is a full sized K5 blazer? What is the resting battery voltage and the battery voltage with the truck running? Repeat that second measurement with meter positive on the alternater output post. Make sure that the battery connections are clean and tight.

George

 

So the battery light must come on, I change the bulb and voila it's charging again. I'm not sure if it's coincidence or what but that is all I did, other then checking a bunch of other stuff fuses and what not. But for anyone with this problem check that battery light on the dash make sure it comes on.

 

On some vehicles the dash bulb is in series with the field winding which provides the initial field excitation at key on and then turns of when the system voltage is high enough.

George

 

That's exactly what's going on here, so she's charging again. I couldn't believe it. It's a 94 blazer 1500 obs 5.7L 2 door.

 

Glad your sorted.

George

 

"Ithe cable going to battery don't have a fuse nothing just straight cable."

Scary. Shouldbe a fuse link.

 

It is quite common for a cable with a fusible link to be mistaken for a straight cable, especially with how many factory positive cables are sheathed in wire loom.

 

+1

George

 

Yes, it can be low profile / not in a over-molded enclosure.

Which makes a case for NEVER just replacing it with a plain wire...