Hi all. I had the Ute die on me a few weeks back ,lost all power at night. Figured it’s gotta be the alternator so got a brand new one. And new battery cause it’s pretty old. Now it’s only reading 11.99 volts at idle . I’ve checked all fuses and connections to the alternator and battery and the battery light on the dash doesn’t stay on. I’m lost where to go next. Have I been sold a dodgy alternator ?
Alternator
- Thread starter Newnav100
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i'm assuming you checked the clutch on the alternator.
it can also be the dash. basically the alternator light is the voltage setting for the regulator.
i think you can test this by putting a small bulb across the sense and voltage line. please double check that before trying it.
later d22's have led alternator light, it also has another diode and a few resistors in the circuit. possibly one or more of those has failed giving lower voltage setting.
it can also be the dash. basically the alternator light is the voltage setting for the regulator.
i think you can test this by putting a small bulb across the sense and voltage line. please double check that before trying it.
later d22's have led alternator light, it also has another diode and a few resistors in the circuit. possibly one or more of those has failed giving lower voltage setting.
How would I check the clutch? It’s brand new so didn’t check anything. It did come with two different size pulleys . Could the larger size pulley be throwing the voltage off
i suspect the new one didn't come with the clutch (as they are very $$$) and came with cheap pulleys instead. pulley needs to be same size as old one, or swap the old one over.
Wasn't aware there was a clutch on a D22 alternator? Thought they were just a solid rotor shaft going through a bearing with a pulley on the end?
It's possible but seems unlikely that both alternators are faulty (but who knows?).
Which model D22 do you have?
Afaik (on the zd30 models at least) the dash light circuit goes to ground through the rotor winding which initially "excites" the magnets. Then the output of the alternator takes over and you get the same voltage on both sides of the dash light (which then goes out). In other words it doesn't do anything after that. So if the alt light is on but then goes out when you start the engine, it seems to indicate at least that part is working ok. Which would make it seem more likely to be a problem with the regulator?
Not sure on other models that use led's and resistors though.
When you say you have 12V at idle, that seems like the alternator has no output at all. What do you get from the alternator itself (from the main terminal) to -ve? What happens when you give it a few revs, does the voltage change?
A wrong size pulley would make a difference re the internal frequency to the diodes, not sure what that would mean for the voltage though. What is the diameter of the one you are using?
Ah, so they have a clutch pulley? Never knew that lol.
It’s a jap built 2008 d22. The voltage is the same at the alternator as at the battery. And the new pulley is 84mm the old one was 70mm
I had a look at the spare I have lying around. If you lock the alternator with a screwdriver into the fan (careful of the windings) the pulley still spins easily in the anti clockwise direction, but I can't move it clockwise. So I'm assuming that's how it should be (as it's brand new).
I would check your old pulley, and if it's ok, replace the smaller one. For starters.
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It’s doesn’t have a clutch it’s free spinning. The larger one is on it now as that’s what it came with. The old one is the smaller one.
"Free spinning" meaning it's locked to the shaft/spins at the same rate as the shaft in each direction? That should still work, but as they're different sizes if the original pulley is alright I would still swap them to see how it goes. Just to rule it out.
not sure if the yd25 ones had the clutch or not. it will still work without a clutch.
i would fit the 70mm, the bigger one will reduce the alternator output.. common rail injectors tend to use a lot of power which is why they have a bigger alt than previous models.
zd30 uses led and resistors. its some of the earlier models that used bulbs.
its a common problem when people upgrade dash bulbs to led, they find the alternator doesn't work properly.
this is why they have the resistors with the led's, it needs to draw a certain amount of current to get the correct voltage (afaik, its been a while).
this is also how can change the voltage output, some people add a diode in series and that bumps the voltage up. many people now use calcium batteries which need higher charging voltage. (ymmv i need to double check that).
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If you need to get back on the road quickly the fixed (conventional) pulley should work.
Within reason, a slightly altered frequency due to different pulley size shouldn't matter if the voltage regulation is working correctly and handles the difference.
(but you are building a limb to walk out on to)
But if your Nav was originally built with a clutched alternator (most modern vehicles are) you'll need to refit it that way for long term reliability.
The "clutch" does a few things, one of which is to enhance the life of the alternator by protecting it from sudden changes in RPM.
The smaller/old pulley will spin the alternator faster. The bigger pulley will slow it down, perhaps it's too slow at idle?
There you go, had a look at the manual and you're right. The page I was looking at was for earlier models.
I can see where replacing a bulb for an led could give problems. The "combination meter" that makes up the dash light consists of a diode >led >resistor in series,with a couple of resistors in parallel with them. So there's more to this design than I thought. Perhaps I'm too old for this stuff, I can still remember when cars didn't have seat belts, and the speedo was in "mph" lol.
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^ Just to clarify: I like that it's fixed, I disagree with the first statement. An idiot wouldn't have found the bonnet latch, let alone know a left-handed socket from a right-handed one.
