[DeTomaso] Alternator swap, alternator indicator is on

Thomas Törnblom thomas at hax.se
Fri Jan 18 03:41:53 EST 2019

I think I know what the problem is.

I have a relay for my DRL where the coil is powered from the I lead and 
I suspect that the Ford alternator doesn't source enough power on the I 
lead to bring it to +12V, which would properly extinguish the alternator 

I will disconnect the relay and verify that this is the issue, and if 
so, I will either need to add a transistor to reduce the current draw on 
this signal, or power the relay from the stator wire, but that only 
provides about 6-7V, so may have to use a different relay.


Den 2019-01-17 kl. 20:22, skrev Thomas Tornblom:
> I've replaced the Bosch alternator in my GT5 with a 130A Ford style 
> alternator from DB Electrical.
> I just started it up to check that everything works, and while it 
> charges, the alternator light doesn't go out, it just gets a bit dimmer.
> Measuring the voltage on the wire to the light I see that it is around 
> 7V, which is about half of what the alternator outputs.
> The stator wire should be around this voltage when the engine is 
> running but I'm surprised that the indicator/ignition wire is at that 
> voltage too. That seems wrong.
> I know that there are owners who have replaced their old alternators 
> with this type of alternator, how have you solved this issue? Skipped 
> the light completely or did you not have this problem?
> I'm contemplating adding a suitable zener diode in series with the 
> wire, but it will take some testing to make sure that the current to 
> the alternator then is enough to excite the field.
> I'm also using this wire to engage the DRL:s, so hard wiring it to 
> switched 12V will kill that functionality too.
> Cheers,
> Thomas

Real life:   Thomas Törnblom             Email:    thomas at hax.se
Snail mail:  Banvallsvägen 14            Phone:    +46 18 32 31 18
              S - 754 40 Uppsala, Sweden  Mobile:   +46 76 209 8320

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