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Hi Guys,
I'm trying to expand my understanding of the alternator lamp circuit, so I won't end up "cooking"
anything during my repairs, tests or mods in the electrical system.
I'm referring to my GQ RB30 here, but I'm guessing the question(s) apply to any charging system.
1)The lamp circuit of the GQ alternator/charging circuit reads +1.5v when the ignition is on and the engine is NOT running. The wire colour in GQ Patrol is white with a red stripe or yellow with a red stripe(depending on the location).
2)When the engine's NOT running and ignition's on, this white wire with red stripe acts as an earth.
3)When the engine's running this wire get energized by roughly +12V
Now, referring to below standard circuit of of the alternator/charging system, I can understand the number 3 above.
But, I'm still lost with 1 & 2, namely how to explain the +1.5V reading on the wire & how it manage to earth.(I'm using typical alternator circuit diagram below to understand it)
I'm guessing regulator circuitry has something to do with that?
I would appreciate if you guys can explain this to me, perhaps with a sketch or a regulator circuit diagram?!
What globe are we referring to?
Are we discussing the typical way the alternator fail(by putting out excess voltage)?
Then the globe(s) tend to blow if left for too long?
Or are we discussing about wiring a voltage sensitive globe(blows above 15V or so) somewhere in the alternator output and place it on the dash or somewhere visible, so we know when the alternator fails?!
What globe are we referring to?
Are we discussing the typical way the alternator fail(by putting out excess voltage)?
Then the globe(s) tend to blow if left for too long?
Or are we discussing about wiring a voltage sensitive globe(blows above 15V or so) somewhere in the alternator output and place it on the dash or somewhere visible, so we know when the alternator fails?!
If you look at the RB30 circuit the globe is in circuit with the field.
If the globe blows the globe doesn't work, and
If the globe blows the Alternator doesn't work as it probably won't flash unless there is sufficient residual magnetism, and lastly
If the globe blows you have no warning the Alternator doesn't work
Ergo, if it is blown nothing works.
Dolphins are so smart that within a few weeks of captivity, they can train people to stand on the very edge of the pool and throw them fish.
The L and IG wires are not the same wires as your GQ they are two different wires.
The L connects to the warning light in the dash (white wire red trace) as well as the auto choke and FPCU.
The IG is the sense wire (white wire) that from factory connects into the main B+ white wire about six inches from the alternator.
ET has explained why/what is happening with 1&2.
Inside the regulator there is a processor, possible a couple of switching transistor, a few diodes and a zener diode from memory.
When the ignition is turned on current flows through the alternator warning light in the dash down through the alternator regulator. This turns the warning on as well as the alternator regulator.
Once the alternator is charging the voltage at the alternator warning light terminal (L) raises to charging rate (say 14 volts). This puts the same potential on both sides of the alternator warning light in the dash (14 volts both sides) so current doesn't flow so the warning light is turned off.
The alternator regulator measures the voltage on the sense wire and constant switches on and off the field circuit to maintain the voltage at it's set level. The higher the electrical demand the lower the voltage the longer the field circuit is held on by the regulator.
Last edited by Yendor; 11th June 2016 at 10:30 AM.
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Originally Posted by mudnut
