boring alternator warning light issue- help needed please

[Dany]

good afternoon

 

i have changed my altenator and now the warning light won't come off when engine running.

i replaced my denso style for another denso style from nipparts (new unit), so they should be the same.

everything was working fine with the previous alternator, but i had to change for some reasons...

 

i have tested the wiring:(ignition ON)

ignition light : around 10.5 volt

exiter wire ;12.5 volts.

 

when engine running, i have 14.4 volt at idle (75 mm pulley) so oviously alternator is charging

 

i have been told some diode pack would not work properly with LED light, hence why the warning light stay on when engine running. i have been advised to use a relay or a resistor but i have absolutly no idea of what that mean

 

would be glad to get some advises from POBC please.

 

merci

[Jonathan Kay]

From the archives:

The same problem

The opposite problem, but includes additional clues

 

Are the terminals on the new alternator exactly the same as on the old one?

 

Are there any terminals on the new one that aren't connected to anything?

 

Jonathan

[Dany]

hi Jonathan

 

yes, terminals are the same and there is no unconected terminals. alternators is the 3 wires type.

 

is it something ok to have 10.5-11 volts on light terminal? (alternator side)

 

from what i read, i should see 0 volt when ig ON...i'm lost...

 

 

[Jonathan Kay]

I don't understand where the LED comes into it. Have you changed the warning light or was it always like that?

 

Is the light on when the ignition is off or only when it is on?

 

Please describe the three wires and where they go.

 

Jonathan

 

Edited by - Jonathan Kay on 14 May 2014 17:06:12

[Dany]

warning light is the OE one, the one in the tacho

 

1.big wire to battery

 

2.ign light to tacho (this one as 10.5-11v when ign ON) goes to L pin

 

3."exiter" (12.5 volts when ign ON) goes to IG pin

 

the light is on when ignition is ON AND when engine running. ign OFF, no light

 

L pin on alternator has 0 volt when engine running

[Jonathan Kay]

I think you now need to either:

 

* Get onto the alternator terminals with a voltmeter and find out what's happening having excluded contact and wiring faults, or

 

* Rig a new light circuit with known good wiring as in the second of those threads.

 

Jonathan

[Jonathan Kay]

PS: If you tell us where you are someone might offer to help.

 

Jonathan

[Dany]

i am in france

 

how would you build a simple external warning lamp?

as long as the alternator is charging ok, is there any risk to use it with the warning lamp issue?

[Dany]

hi

it seems like the live feed has been taken from somewhere in the loom. it gives 12.5 when ign ON so should do the job correctly but should it be linked to the warning lamp?

cheers

[elie boone]

With ignition on you should have 12v on 1 side of the warning light and - on the other when the engine is running you should have 12V both sides. There is no problem in wiring an external warning light.

[Dany]

that may be the probleme

 

the wire that comes from tacho to alternator (lamp) has 10.5-11 v when ignition on (alternator side).

i have tested another tacho and the probleme is the same so it shouldn't be the culprit

 

if i follow you, i should see 0 volt when ign ON, and 12.5 when engine running?

[Jonathan Kay]

Quoting Dany: 

the wire that comes from tacho to alternator (lamp) has 10.5-11 v when ignition on (alternator side)?

Think of that as going alternator to tacho rather than the other way. It should be at roughly 0V with ignition on and engine off, and roughly 12V with ignition on and engine running and alternator charging.

 

The other side of the warning light is always at 12V. So in the first condition it has 12V across it and illuminates. In the second condition it sees the same voltage both sides and doesn't illuminate.

 

A faulty wire or connection means that the 12V difference across the bulb continues to exist even when the alternator is charging.

 

Jonathan