A conundrum solved

[Z-train]

A while back i replaced the instrument light bulbs with L.E.Ds.While i was there,i did the high beam indicator & alternator bulbs.After that,the alternator light would stay on untill i revved it above 1500 rpm.And while at freeway speeds at night i could see the light(alt)flickering.So i changed back to the 161 bulb and all is normal again-no issues.

 

Go figure.... :hmm:

[ggzilla]

because the alternator gets the sense signal via the CHG lamp in the dash... and so won't work if a diode (L.E.Diode) is fitted instead.

[Z-train]

because the alternator gets the sense signal via the CHG lamp in the dash... and so won't work if a diode (L.E.Diode) is fitted instead.

in other words..draw?

[hang_510]

doesn't installing a diode on the sense wire solve that?

 

i had to with the IR alt i'm running. otherwise the chg light stayed on.

[DanielC]

LED lights draw a lot less current than an incandescent lamp.

The incandescent lamp, when it is off, probably still has a small amount of current going through it. Not enough current to light the incandescent lamp, but more than enough to make a LED glow brightly.

[philcas1987]

diodes job is to let voltage one way right? charge light gets 12v power from ignition switch and ground from alternator. whith the engine running alternator sends poewr back. now the bulb is getting power on both sides casing the light to go off. wont an led affect that whole design be cause it lets current one way but not the other. causing charging issues?

[ggzilla]

That's a theory. To test it, put all the LEDs back in, except fro the CHG lamp. If it works OK, then you know it's that one LED.

[Just Joel]

Just did this myself and had a similar issue... couldn't figure out why the alternator wouldn’t charge until I jumped (momentarily) the white black signal wire to a 12v source at the alternator. I saw this thread and gave changing the bulb back a try and whala, it worked. I guess we don’t get to use an led for the charge light? :confused: Funny thing is I still had to set the idle at about 800 for it to work even with the standard bulb. Hmmm, now that I think about it might not be a factory 161 bulb, are these things that sensitive? If the bulb burns out does the charging system stop working?

 

Thanks

Joel

[datsunaholic]

If the alternator light burns out, then it'll be hit-and-miss if the charging system will function. Sometimes the auto-choke relay (if connected) is enough to get the alternator field started. Sometimes the alternator can build its own field. My Chevy had a bad bulb and the charging system would start working if I revved the hell out of it. Change bulb, problem solved.

 

If you want to run an LED, here's an idea. In addition to the diode, run a 70Ω resistor in PARALLEL with the LED (not in series). It will need to be at least a 3 Watt resistor.

[Just Joel]

Really for as little as this light is on its not a big deal if I don’t use an led but it’s interesting how this system works. Glad to know my charging issue was so simple to fix.

 

Thanks

Joel