Alternator woes
#23
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#24
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No, I expected it was disconnected and just wanted to confirm. It will be about 0.5V connected.
I believe that you could connect a resistor between an ignition switched source and the L wire, with the BCM still connected. A resistor around 100ohms and 5W is the value I would try.
The reasoning is this. The BCM basically has a current limiting circuit that provides power to the L terminal. The alternator uses this current as the signal to start working, combined with it rotating once the engine is started. The rebuilders are using the wrong regulator circuit and their regulator circuit requires a higher current into the L terminal. So, adding the resistor would boost the current and "kick-off" the regulator without having to first rev the engine.
The problem is that I don't know if it will work. There is a chance it could damage the BCM, but I don't believe it will. The BCM output already gets shorted by the alternator so a short on that circuit won't damage the BCM. The BCM also has full battery voltage applied to that circuit (vehicle running and alternator charging) so a resistor also attempting to apply full battery voltage shouldn't damage it.
Of course, the better solution is to find an alternator that works. Unfortunately, it is somewhat of a crap shoot. An alternator that works for one person doesn't mean it will work for another. The only way to know is to get one with the correct regulator where you can confirm the regulator part number.
I believe that you could connect a resistor between an ignition switched source and the L wire, with the BCM still connected. A resistor around 100ohms and 5W is the value I would try.
The reasoning is this. The BCM basically has a current limiting circuit that provides power to the L terminal. The alternator uses this current as the signal to start working, combined with it rotating once the engine is started. The rebuilders are using the wrong regulator circuit and their regulator circuit requires a higher current into the L terminal. So, adding the resistor would boost the current and "kick-off" the regulator without having to first rev the engine.
The problem is that I don't know if it will work. There is a chance it could damage the BCM, but I don't believe it will. The BCM output already gets shorted by the alternator so a short on that circuit won't damage the BCM. The BCM also has full battery voltage applied to that circuit (vehicle running and alternator charging) so a resistor also attempting to apply full battery voltage shouldn't damage it.
Of course, the better solution is to find an alternator that works. Unfortunately, it is somewhat of a crap shoot. An alternator that works for one person doesn't mean it will work for another. The only way to know is to get one with the correct regulator where you can confirm the regulator part number.
#25
Le Mans Master
Lionelhutz, do you think the L terminal voltage is too low. Could it be his ignition switch is limiting the voltage? It should be about full battery voltage at around 12.5-12.6.
Mr. Sam
Mr. Sam
#26
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No, the circuit is in the PCM seems to provide about 10V with just the key on. The most likely problem is that the circuit limits the current too much.
I expect the battery voltage when running is provided by the alternator. To test it would require removing the wire with the engine running and alternator charging. But, the voltage sensing wire would have to remain.
I expect the battery voltage when running is provided by the alternator. To test it would require removing the wire with the engine running and alternator charging. But, the voltage sensing wire would have to remain.
#27
Le Mans Master
I was afraid you would say that. The FSM says it should be 12 volts and says to just measure to make sure it is "near" there, no tolerance.
OP, would you be willing to go back to AutoZone and try another one? I don't think it is your car but the alternator.
Mr. Sam
OP, would you be willing to go back to AutoZone and try another one? I don't think it is your car but the alternator.
Mr. Sam
#28
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I'll give it one more go from AutoZone, but if it doesnt work this time around I'll probably cave in and pick on up from the dealership...
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Well, I tried another from AutoZone and had the same results. So, I decided I'll just have to live with it for the moment. Dealership is crazy for asking $700+. Maybe if I get too tired of it I'll try a used Valeo from eBay.
I appreciate everyone's help, but I think I'm stuck for now.
I appreciate everyone's help, but I think I'm stuck for now.
#33
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Zags
If you pm me your name and address I will buy a voltage regulator for you to try out. If it works, you pay me the price for the regulator (less than $35.00). If it doesn't work just send me the new regulator.
Bigdad
If you pm me your name and address I will buy a voltage regulator for you to try out. If it works, you pay me the price for the regulator (less than $35.00). If it doesn't work just send me the new regulator.
Bigdad
#35
Melting Slicks
This forces me to pose the question. If this regulator is at the heart of the issue on the earlier C5s, is it just a matter of putting the correct regulator on a new unit? Would this also work for the higher 145a output alternators? Hmmm... what a tangled web we weave with this stuff...
#36
Intermediate
This forces me to pose the question. If this regulator is at the heart of the issue on the earlier C5s, is it just a matter of putting the correct regulator on a new unit? Would this also work for the higher 145a output alternators? Hmmm... what a tangled web we weave with this stuff..
I'm thinking the same thing. That is why I'm looking for a 145a off of a 04 corvette, so I can put the other regulator in it and see if my 98 would like the 145a.
Bigdad
I'm thinking the same thing. That is why I'm looking for a 145a off of a 04 corvette, so I can put the other regulator in it and see if my 98 would like the 145a.
Bigdad
#37
Melting Slicks
Well, I tried another from AutoZone and had the same results. So, I decided I'll just have to live with it for the moment. Dealership is crazy for asking $700+. Maybe if I get too tired of it I'll try a used Valeo from eBay.
I appreciate everyone's help, but I think I'm stuck for now.
I appreciate everyone's help, but I think I'm stuck for now.
Last edited by GCG; 01-26-2016 at 07:42 AM.
#38
Melting Slicks
That is a very interesting idea... It seems that, in principle, it should work (as long as the 97-01 regulator could handle the 02-04 rotor)! Please, let us know how it goes
Last edited by GCG; 01-26-2016 at 08:55 AM.
#39
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Finally got a chance to pull the back off of the alternator. Here's the regulator that's on it now. Text says VRPR1935. A Google search for which brings up a few dozen websites all in Russian.
Click for full size.
http://postimg.org/image/pbuq7hl6d/
http://postimg.org/image/mf5ianwtr/
http://postimg.org/image/ipqi1temd/
As Bigdad suggested, I'm going to buy a Valeo regulator, stick it in the AutoZone unit, and cross my fingers. I'll let you guys know what happens...
Click for full size.
http://postimg.org/image/pbuq7hl6d/
http://postimg.org/image/mf5ianwtr/
http://postimg.org/image/ipqi1temd/
As Bigdad suggested, I'm going to buy a Valeo regulator, stick it in the AutoZone unit, and cross my fingers. I'll let you guys know what happens...
Last edited by Zags; 01-26-2016 at 07:56 PM.