2nd Gen Non-Engine/Transmission Alternator

[Neibe]

I replaced the alternator 10 months ago and the rebuilt one went bad the other day. It had a lifetime warranty on the rebuilt, when I took the bad one in Autozone tested it it failed however they said the only part of it that failed was the voltage regulator. They said the voltage regulator is in my computer it could be my computer. So I put the new one on and everything works. So my question is this if the voltage regulator is in the computer how could they tell it was bad cause the alternator was off the truck when they tested it. Also, I didn't think my truck had a computer as it is a 12 valve and has a manual transmission what does the computer do if it doesn't control the engine and doesn't tell the transmission when to shift.

 

[Moose Truck]

Ok, the PCM does do the voltage regulation. It also runs the cruise control, the AC Compressor, the Tach and on the 12Valve trucks, maybe the rest of the Instrument Cluster (It does on the 24Valves). This is were the Gasser trash trucks do it, along with the Fuel Injection and Ignition stuff.



AutoZone most likely found the alternator is putting out the right Voltage and Amperage, so the PCM or the wiring had to be bad. Moose

 

[DieselDoghouse]

Sadly it can depend who tested your alternator. As has been said if it will output +12V when spun then "its OK and it must be your truck". The truth is the only good way to test an alternator would be to put it on an oscilloscope while under load (looking for sharp peaks from each winding). An alternator is actually three generators in one package with their outputs wired together. Six rectifiers (two per winding) ensure that they all share the load equally. Lose just one rectifier and you can still get 12V but you won't get rated current under load. You will get a real hot alternator since during part of its output cycle one winding might actually be dumping into the others (need those diodes). I have doubts the Autozone personnel (no offense intended) would be able to troubleshoot the diode array!!. Now that I've confused you - if you have a service manual you'll see the schematic for charging shows the alternator as a WYE with a common ground but the 2 diodes head-to-tail—to keep current coming out but not going into each winding. I find these are #1 source of '12V failure'. If you had lost your brushed (they feed the spinning part) its simpler - no output anywhere

 

[VHolloway]

what would happen if you went with a hi amp alternator like 250amp would it cook something

I have a cb radio and a linear i wanted to put in the trucK but I need a bigger alternator

the linear is a texas star dx16 sweet 16

 

[JFaughn]

Alternators are not meant for full time use , does not matter how many amps , I do not know the spec's of what your doing but 120 130 amps at 12v is a lot of power [ over 1,400 watts ] , its best to run off the batteries unless you use a lot with truck off , then separate deep cycle batteries .
Its nice that the do it yourself parts houses do testing for free , but then you have too many that do not have a clue spending your money & time .
If it works for a while [ before it dyed ] & the 3rd one , the regulator most likely is working , maybe a connection problem , having the right tools [ load tester ] and someone who knows what there doing - we can help with the knowledge but have the load tester is what you need .

 

[DieselDoghouse]

Actually alternators DO have to work 100% of the time but shouldn't at 100% capacity - this can be best calculated by the specialty houses that would supply a upgrade alternator. Example: if you have a 1400 watt continuous load you shouldn't put your faith in a 1400 watt (peak) alternator, and just because you have hefty batteries (or you add a battery) don't think it'll all work out. In a 500 mile trip you are bleeding your batteries down—no matter how many, OR you are asking the alternator to deliver well into its reserve capacity ALL the time. Now you can add an alternator but now you really need an engineer to coordinate the two!!

 

[Neibe]

Since the alternater failed they did replace it and the new one works perfectly. So I'm thinking the computer is o. k.

 

[DieselDoghouse]

'Course it is, and NOW so is the diose array in the NEW alternator Best of luck with this one.