Battery light

While driving my 2006 5.3 Z 71 1500 LT. A couple of weeks ago my battery light come on. I sweat going to my destination and when I leave the battery light is off. This have been going on a while. I stopped at Auto Zone (several times) and they did an in the vehicle test, Alternator is so low it can't be measured. The next day after charging the battery the alternator is putting out like a $5.00 you know what and the battery (18 months old) load test just fine. I did this several times; even with the battery light on the alternator is charging. So I did some reading and found that the inductive pickup on the Neg. battery cable sends signal to the PCM which in turn energizes the alternator field (so it makes amps) when a load is sensed. I replaced the inductive Generator/ Battery thing and I still have this issue. Is this a PCM issue or a bad alternator? My truck has 174 k Miles on it. BTW when you replace the inductive pickup you either have to remove the battery cable at it's other end, presumably on the block somewhere or cut the battery end off, run the cable through the sensor and install a new end. Thanks GM.

I suspect it's the alternator.  Our 'ole Suzuki's hat sry light was coming on and would go out after a few minutes of driving.  Eventually it stayed on longer and longer (over many months). Got to the point it cooked the battery.  Got a new battery, light stayed on.  Replaced the alternator and all is good.

I'm with frito on this one.

EXT4ME said:

I'm with frito on this one.

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frito said:

I suspect it's the alternator.  Our 'ole Suzuki's

frito said:

I suspect it's the alternator.  Our 'ole Suzuki's hat sry light was coming on and would go out after a few minutes of driving.  Eventually it stayed on longer and longer (over many months). Got to the point it cooked the battery.  Got a new battery, light stayed on.  Replaced the alternator and all is good.

Click to expand...

light was coming on and would go out after a few minutes of driving.  Eventually it stayed on longer and longer (over many months). Got to the point it cooked the battery.  Got a new battery, light stayed on.  Replaced the alternator and all is good.

Click to expand...

I get the logic, but cause and effect aren't necessarily the same when you have 2 different designers drawing up the wire harness; different engineers do the same thing(s) differently. It's a certainly the dealer isn't going to shed any light on the issue for free....It'll be an hour of trouble shooting at $120-$130 an hour and then MAYBE you have the solution. If the dealer (or anyone else) had higher batting averages when troubleshooting it might be $$$ well spent. I just don't have that much faith in those people. But I am hoping it's the alternator and not the PCM. My issue here is I'll get a alternator and find out it's the PCM. I got a FLASHING Check Engine light last night, ran the codes and came up with a #8 cylinder misfire, I just changed the plugs and IGN. wires so I cleared the code and checked that the IGN. wire was securely in place. We'll see today...

I replaced the alternator, THE MAN has a pretty good local (read expensive) shop says intermittent alternators happen all the time especially on Fords....

I just watched a Youtube video this morning where tech had a Mustang in for what he was told was a faulty cam position sensor.

He walked us through his troubleshooting and showed where the actual problem was a faulty diode in the alternator.

I found it fascinating to watch him reason through the process of actual testing to eliminate and confirm.

So far the dash light hasn't come on, my truck still runs like crap so it wasn't a bad diode in the alternator... I understand that the cam position sensor in near the oil pressure sending unit, I laid down under the hood and i couldn't see it... Is a mirror required to see it?

https://www.youtube.com/results?search_query=chevy+silverado+camshaft+position+sensor+