alternator light doesn't come on ??

[ty901]

all;
i've searched the archives and can't find a scenario like this, so...
car is a '69 911E upgraded to a 75 amp Paris-Rhone (int. reg.)
problem; alternator light does not come on with the key 'on' and the engine not running.
when i originally bought the car about a year ago, the alt. light would come on w/ the key on and go out when the engine started. some time thereafter i toasted the wiring for the instrument lights. now i'm guessing that's when the alternator light went out also.
the alternator died about a month ago. (several months after the alt. light went out) bench testing showed it to be producing 9.5V. on fully charged batteries the car would last for about 20 minutes, then slowly die, FWIW.
i have a good replacement alternator installed. i understand the concept of what the alternator light is supposed to do. the bulb tests good (VOM ohm = 0) i get 12V to the bulb, but it doesn't light as it should.
any help greatly appreciated.
best
jerry

[304065]

When you connect a jumper wire to pin #11 of the 14-pin connector on the electrical console and ground that wire, what happens?

The light should come on.

[ty901]

hi John;
i'd be happy to give it a shot. where is the "...electrical console" ? sorry, relatively new to 911's.
THANKS!
jerry

[john walker's workshop]

the light gets power with the key on, and a blue wire goes from the other side of the light to the engine compartment where it connects to the voltage regulator and continues on to the alternator D+/61 terminal where it finally completes the circuit and grounds, which lights the bulb. find the blue wire on the regulator and ground it with a jumper wire and see if the bulb lights. if it does, the alternator brushes are probably not contacting the commutator. the bulb circuit must work for the alternator to kick into the charging mode.

[ty901]

**find the blue wire on the reglator and ground it with a jumper wire **and see if the bulb lights.
****************************************

this is making sense to me. although because of the upgrade, i'm not sure the wire is blue anymore, but i know the wire that bolts to the /61 terminal. (stator ?)

i'll give this a shot & post back.
THANKS AGAIN !
cheers
jerry

[304065]

Listen, the D+/61 "blue wire" bolts to the terminal labeled like that on the back of the alternator. If you have the alternator out of the car, then touch that blue wire to the engine block with ignition on. The light should come on.

It's not the stator, it goes inside to the internal regulator, and through the regulator to the rotor.

[ty901]

all;
my D+/61 wire is red, so i hope we're on the same page. bottom line is that the bulb does NOT light when i ground that wire. again, 0 resistance through the bulb and i get 12V on either side of the bulb holder with the bulb installed, FWIW.
next ? ;-)
TIA
cheers
jerry

[911mot]

Check for continuity between bulb and D+/61 wire in engine compartment.

Check engine earthed OK too.

[ty901]

small ground strap from engine center bolt to fan housing was freshened up.
tracing as you suggest sounds logical. any specifics ?
TIA
cheers
jerry