From gnttype.org
Alternator Facts
The Alt. used on the 84/85 is a 12SI. SI stands for Systems Integral. The was the first GM alt that was internally regulated. It debuted in 1972. (That was a 10SI) Of course, GM was the first to come up with an internally regulated system. This system was an excellent system. It is so easy to work with and is a good design. Well, in the 1980s with all of the computer controlled cars coming out, GM needed an alternator that could communicate with the ECM. In 1986 the CS series Alternators came about. CS stands for Charging Systems. The models, CS121, CS130, CS144 and now CS130D(this is another story!
The number after the CS is the diameter of the stator in Millimeters. So, on the 86/87 TR it's 144 Millimeters wide. Most all of the CS series unit put out over 85 amps. The TR Alt. doesn't communicate with the ECM. Instead, the regulator monitors everything. It counts the AC counts so it knows how fast the alt is spinning. and can even cut the charge back if necessary. There are over 8 different regulators used in the CS series. They all look and plug in the same but they are different internally. I could go on about what each regulator does differently but that's another time The number is stamped on the regulator. On the 86/87 TR's it usually a 411. If you have any questions about your charging system please, feel free to e-mail me. GM by FAR has the best charging systems on the market today.
Alternator Wiring
On the 84/85 the regulator plug in there are two wires. A small and a large. The large one(number 2) has 12v ALL the time. The small wire (number 1) is hot when the key is on and has less than 12v usually around 8 or so. The main post has 12v all the time, also.
On the 86/87 the main post has 12v all the time. The little brown wire has ~2.5v when the key is on.
On both alts, the idiot light works the same. The idiot light circuit applies to the number 1 wire(Small) on the 84/85s. When the Alt. is not spinning or not charging, that regulator terminal is a GROUND. When the alternator is charging it is a positive. Two positives DON'T complete a circuit so the light is off.
Alternator Models/Parts
The Lester number for the 84/85 TR alt is a 7294. It is a 94 amp unit.
The Lester number for the 86/87 TR is 7814. It is rated at 120 amps.
The bearings for the TR alts are as follows: 84/85 front bearing is a 6203, Rear is a needle bearing. On the 86/87 Front bearing is also a 6203 and the rear is a 6000. ALWAYS replace these. It's cheap insurance.
Well, I hope this helps you out when doing your TR alt. If you have any questions please contact me. We would be more than happy to assist you in this. If you get frustrated or just don't want to do it we would be glad to rebuild it for you. Just E-mail us and we will get you straightened out. We carry all parts for these alternators.
http://www.gnttype.org/techarea/electrical/alt.html
HTH
Alternator Facts
The Alt. used on the 84/85 is a 12SI. SI stands for Systems Integral. The was the first GM alt that was internally regulated. It debuted in 1972. (That was a 10SI) Of course, GM was the first to come up with an internally regulated system. This system was an excellent system. It is so easy to work with and is a good design. Well, in the 1980s with all of the computer controlled cars coming out, GM needed an alternator that could communicate with the ECM. In 1986 the CS series Alternators came about. CS stands for Charging Systems. The models, CS121, CS130, CS144 and now CS130D(this is another story!
The number after the CS is the diameter of the stator in Millimeters. So, on the 86/87 TR it's 144 Millimeters wide. Most all of the CS series unit put out over 85 amps. The TR Alt. doesn't communicate with the ECM. Instead, the regulator monitors everything. It counts the AC counts so it knows how fast the alt is spinning. and can even cut the charge back if necessary. There are over 8 different regulators used in the CS series. They all look and plug in the same but they are different internally. I could go on about what each regulator does differently but that's another time The number is stamped on the regulator. On the 86/87 TR's it usually a 411. If you have any questions about your charging system please, feel free to e-mail me. GM by FAR has the best charging systems on the market today.Alternator Wiring
On the 84/85 the regulator plug in there are two wires. A small and a large. The large one(number 2) has 12v ALL the time. The small wire (number 1) is hot when the key is on and has less than 12v usually around 8 or so. The main post has 12v all the time, also.
On the 86/87 the main post has 12v all the time. The little brown wire has ~2.5v when the key is on.
On both alts, the idiot light works the same. The idiot light circuit applies to the number 1 wire(Small) on the 84/85s. When the Alt. is not spinning or not charging, that regulator terminal is a GROUND. When the alternator is charging it is a positive. Two positives DON'T complete a circuit so the light is off.
Alternator Models/Parts
The Lester number for the 84/85 TR alt is a 7294. It is a 94 amp unit.
The Lester number for the 86/87 TR is 7814. It is rated at 120 amps.
The bearings for the TR alts are as follows: 84/85 front bearing is a 6203, Rear is a needle bearing. On the 86/87 Front bearing is also a 6203 and the rear is a 6000. ALWAYS replace these. It's cheap insurance.
Well, I hope this helps you out when doing your TR alt. If you have any questions please contact me. We would be more than happy to assist you in this. If you get frustrated or just don't want to do it we would be glad to rebuild it for you. Just E-mail us and we will get you straightened out. We carry all parts for these alternators.
http://www.gnttype.org/techarea/electrical/alt.html
HTH
