alternator wiring connections

[cudanutz]

ihave a newly bought 69 cuda and the alternator didnt seem to work- upon replacing it unsuccessfully with a second aftermarket one ( Bosch) -( the terminal connections are marked ;batt- field + field -with a wiring explanation to ground the field terminal next to the batt one for single wire operation ? as i have only one feed wire plus the batterry -alternator wire i wonder if this is the case ? ) after installation & tight belt pulley there is still no voltage being produced at the " batt" terminal to grnd with one field terminal connected recieving 8-9 v from the regulator - ( non electronic ) -and not feeding or grounding the second field - which on my old alternator was marked "grnd" - this 2nd field terminal reads 8 v. even when not connected ? how can this be "grounded" as instructed and NOT short out ? . my 2nd question is; do you have to supply a feed to both fields to get the charging voltage up ? also the" batt" WIRE from the dash is live with 12 v -is this normal ? - do i have another faulty alternator needing a bench test - or maybe an on board wireing problem . any help out there ? im in the twilight zone on this one thanks cudanuts

 

[dgc333]

I am assuming the aftermarket (Bosh) alternator is a replacement unit not something you are trying to adapt. If it is then, ground one of the field terminals to the case of the alternator (doesn't matter which) and connect the other one to the green wire from the regulator. You have to have a circuit from the voltage regulator to ground through the field windings in order for current to flow and create a magnetic field before the alternator will output current. The regulator will switch the voltage on and off to regulate the output of the alternator.

Sounds like the alternator is one that could be used for 70 up systems where 12 volt is attached one field terminal and the other is grounded through the regualtor. But in your system you have to have one of those field terminal grounded.

Also, you should be reading close to battery voltage on the green wire from the regulator if the other field terminal is not grounded. I would check connections and the ground on the regulator to.

The output wire from the alternator goes through the firewall bulked connector to the amp gauge, back through the bulked connector to the battery. This is a commonplace to have bad connections or a bad amp gauge. Make sure these connections are clean and tight and you have continuity from end to end.

 

[cudanutz]

thanks Dave -you have given me a better insight to my de-lahma and i wont have to remove it again to bench test . i was leary that the voltage on the second field terminal if grounded would short out the wiring or diodes - and yes the bulkhead symptoms im very familiar with as 2 of my other A bodies have that wiring problem remedied by going through with no connections thanks again rofiler: cudanutz 67 notchback 318 69 "cuda" FB 383 4sp 69 318 barracuda FB 72 318 dart swinger 69 383 4sp NM Road Runner post