Wiring factory tacho to aftermarket alternator

[walker]

Hi all,
I know this has been covered before and in a previous thread it was said that an auto elec can add a W terminal to the alternator for the tacho.

I have a Bosch alternator from a falcon and the auto elec told me he cant add a terminal for the tacho.

He did suggest trying the tacho on the "-" terminal on the coil. Does anyone know if this will work.

(I cant test it out yet because the Rangie is still not running)

thanks,

Adam

[PhilipA]

The auto electrician must be pretty bad.
The wire is added to one of the field wires.
I have a Bosch alternator and have had a "field' wire added for the tacho.
Just remember your pulley must be the same diameter as original or the tacho will read incorrectly.
Regards Philip A

[walker]

but how about the negative on the coil?

[PhilipA]

but how about the negative on the coil? 24th March 2009 01:47 PM
I have no idea, because it is designed to run off the alternator.

I doubt whether the calibration would be correct .

8 pulses per revolution, vs 1 at alternator but gear reduction by 50%???

You could of course have it recalibrated by an instrument place but the field wire should only cost $40.

AFAIR there is a how to somewhere on this forum.

Regards Philip A

[Bushie]

Something in the back of my mind says it's dependent on how the alternator is wound - Star v Delta windings, but no doubt someone will have the right answer.


Martyn

[toey1977]

going off subject here a little does the alternator control the fuel injection as well?, and there are days when driving home my tacho is all over the place for example it normally reads about 2200rpm at 100 kmh but then theirs time it drops and tells me its doing 1500rpm at 100kmh the it sits there and bang will jump back to 2200rpm at 100kmh, got any thoughts on this

88 RRC 3.5 EFI on gas

[PhilipA]

Dying alternator or loose fan belt.
Regards Philip A