Idle Voltage On 97 Z71

[Dyabolical]

Here is the chain of events.

 

When i would go to start my truck, the starter would spin, but it wasn't making contact with the flywheel. So i replace the starter and it works fine for a week and then starts up with the same thing as before. So i go and out of curiosity have my battery checked. The guy opens the hood and starts cracking up laughing. Big truck....tiny battery. I guess i never paid attention to what i had in there. Anyway, the battery that i had was like....450 amps or something like that.

 

So i go ahead and get a 1000 amp battery, 850 CCA i think. New battery and everything works just fine. I also had the stock alternator checked and it was doing fine.

 

So a few weeks later i pick up my new CD player. Pioneer 880PRS. Awesome little deck, lots of functions. One of the functions is a voltage meter. So i get it hooked up and decide to go for a quick drive.

 

So i am cruising down 1-44 doing my usual 65 mph and i hit the button to check voltage. At 65 i was showing a constant voltage of....a whopping 12.3 volts.

 

This can't be good.

 

So i think the deck might be wrong. So i hook up my DMM and sure enough, my voltage is sitting at ~12.3 volts.

 

I am a little confused on this. My battery isn't draining, my alternator checks out just fine. So why am i not at the usual 13.8v, or the target voltage of 14.4v?

[redvett]

That correct and you should see 14+V at startup. A fully charged battery will read 12.75+ V and an alternator cannot fully charge a battery only a generator or a battery charger.

[rogerf]

Here is the chain of events.

 

When i would go to start my truck, the starter would spin, but it wasn't making contact with the flywheel. So i replace the starter and it works fine for a week and then starts up with the same thing as before. So i go and out of curiosity have my battery checked. The guy opens the hood and starts cracking up laughing. Big truck....tiny battery. I guess i never paid attention to what i had in there. Anyway, the battery that i had was like....450 amps or something like that.

 

So i go ahead and get a 1000 amp battery, 850 CCA i think. New battery and everything works just fine. I also had the stock alternator checked and it was doing fine.

 

So a few weeks later i pick up my new CD player. Pioneer 880PRS. Awesome little deck, lots of functions. One of the functions is a voltage meter. So i get it hooked up and decide to go for a quick drive.

 

So i am cruising down 1-44 doing my usual 65 mph and i hit the button to check voltage. At 65 i was showing a constant voltage of....a whopping 12.3 volts.

 

This can't be good.

 

So i think the deck might be wrong. So i hook up my DMM and sure enough, my voltage is sitting at ~12.3 volts.

 

I am a little confused on this. My battery isn't draining, my alternator checks out just fine. So why am i not at the usual 13.8v, or the target voltage of 14.4v?

So where exactly are you reading the 12.3V? From the radio or the dash gauge, or a meter? If it's coming from the radio, there is no way to tell if the line voltage is altered through the radio electronics. Do you get a voltage drop if the lights are turned on?

 

The most accurate way to check alternator output is with a hand-held multitester. Check the voltage across the battery terminals with the truck running and shut-off, you should see a slight differential. If you still think it's low, might be something a simple as a weak ground.