Alternator 18V? now not working!

[gost]

Hi I have two 453, from -01 and -95, now the other day the one from -95 charged 18V? in a few minutes, and now it seems not to charge at all - I guess I have to replace the alternator? Cause I guess the component regulating the voltage is inside the alternator? /Göran

 

[OldMachinist]

Yes the voltage regulator is built in on the small Denso alternator the 453 uses. Here's a link to a service manual for the Denso alternators. http://www.autoshop101.com/forms/h8.pdf

 

[jeffco]

Yes the voltage regulator is built in on the small Denso alternator the 453 uses. Here's a link to a service manual for the Denso alternators. http://www.autoshop101.com/forms/h8.pdf

Although it is unusual for the regulator to fail and produce 18+ volts, usually it progressively falls below 12 volts. Generally there will be a ground in the field circuit causing the overcharge. So before you invest in an alternator, try unplugging the 2 wire connector to the internal regulator and check the charge rate. At that point it should be at or below battery voltage. If it's still high there is a better than average chance it's an internal problem in the alternator. If you plug the 2 wire plug in and it resumes 18+ volts you may have a harness problem, possibly a ground or a short to B+. Give me a Denso number and I'll furnish you with the wiring diagram for the alternator. One word of caution, if these 45 amp Denso alternators are over worked they usually burn the rotor winding which causes no charge. Jeffco