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Quick fire question


geoffbeaumont

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Got a 105Amp Bosch alternator out of a Mondeo today to replace the ailing original item.

Only one catch, it's got an extra wire...where does green and black go to? Anyone making chocolate references will be shot at dawn...

It's got red and black, white and black and the big hefty orange one same as the lucas. What do I do with the extra wire?

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Or to put it another way - ignore it ;)

According to RangeRovers.net the white and slate wire goes to the alternator. That's for another alternator with the same wires as my old one, though.

The wires on this one are just labeled 1,2,3 on the multiplug - no other identifiers on the plug or alternator.

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Erse - this isn't even close to a drop in replacement. The bracket's far too wide for the alternator. Wonder how secure it'd be if I removed the bottom lug? Looks like the only way forward - modifying the bracket would mean removing it from the engine, and that means removing all the ancillary brackets on this side of the block :(

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Duck tape and bailing twine :ph34r:

Nearly...hacksaw attack followed by cable ties...scrapheap challenge here I come :D

Looking at this and this, I reckon the red wire actually needs to go to the battery terminal (seems to go to the starter motor on some cars (fig 2.3.1c)? It's thicker than the white and green wires (under the light in here I think they're white/green and green/black). The red is just plain red.

Help :blink: I'm a bit out of my depth here...

So my current thinking is:

Red to battery post

white/green to tacho (existing white/black)

green/black to charge light (existing brown/yellow)

Sound any good?

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Okay - Jonathan and his DVM to the rescue:

red to battery post (must be connected or charge light doesn't work)

green/black to charge light (existing brown/yellow)

white/green leave disconnected. It's not a tacho input, whatever it is...

I've got no tacho for now, but I can live with that. Cable ties got an upgrade to binder twine and it's all reasonably secure :)

Running beautifully again :D

Thanks all.

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suppose green/black to brown/yellow makes sense as the green/black is normally an ignition switched feed, which it is after it's gone through the bulb :huh: job done anyway :)

Apart from one small detail - I forgot that while I operate just fine without a tacho signal, the EAS controller is a little more picky :rolleyes: It will happily lower the suspension (on a whim, per standard operation...) but won't pump it up unless engine revs are above a certain limit. Spot the flaw...

Think I'll be looking that EAS ECU pinout out tonight, Tony :lol: Might just motivate me to get a move on with the EDIS stuff too, since that'll give me a tach signal. Wonder if I can sort it out before the weekend...I was planning on putting in an appearance at Llanerchindda on saturday :huh:

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Wonder if I can sort it out before the weekend...I was planning on putting in an appearance at Llanerchindda on saturday :huh:

Well, the Escort's gone, but it's new owners turned up to collect it during what little was left of my truck fixing window after some idiot spilled petrol all over the M42 :angry: so I won't be seeing you all in Wales this weekend :(

Have fun! :)

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Well, the Escort's gone, but it's new owners turned up to collect it during what little was left of my truck fixing window after some idiot spilled petrol all over the M42 :angry: so I won't be seeing you all in Wales this weekend :(

Have fun! :)

It is a tacho feed! But it is not pulsed as you might expect.

Have you ever wondered why the tacho reads right regardless of the size of the pulley? It still reads right if you change the pulley or alternator?

This is dead clever! The wire is a feed from the unregulated power output of the alternator. When the engine is running, when each cylinder fires, the engine accelerates a tiny bit and then slows down before the next one fires. This gives a tiny ripple in the unregulated alternator output. The rev counter just counts the ripples. The output usually sits at about 6v - but you will need a sillyscope to see the ripples.

Si

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It is a tacho feed! But it is not pulsed as you might expect.

Have you ever wondered why the tacho reads right regardless of the size of the pulley? It still reads right if you change the pulley or alternator?

This is dead clever! The wire is a feed from the unregulated power output of the alternator. When the engine is running, when each cylinder fires, the engine accelerates a tiny bit and then slows down before the next one fires. This gives a tiny ripple in the unregulated alternator output. The rev counter just counts the ripples. The output usually sits at about 6v - but you will need a sillyscope to see the ripples.

Si

Thank you Simon for those words.

I spent a lot of time last year trying to find out why this was the case.

You are only the second person to tell mye this.

I eat rat poison

mike

I can cause trouble in an empty houise !!

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which mondeo did the alternator come out of? how old? i thought they were less amperage :unsure:

A mark 2 - hard to say more than that, there wasn't much left of it! I'm guessing it was either high spec with lots of toys or a diseasel?

The 90Amp alternators I found at Stirchley breakers where, I think, a different fitting and maybe would drop straight on to a Land Rover bracket? I wonder if they were from mark 1 Mondeos?

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It is a tacho feed! But it is not pulsed as you might expect.

Have you ever wondered why the tacho reads right regardless of the size of the pulley? It still reads right if you change the pulley or alternator?

This is dead clever! The wire is a feed from the unregulated power output of the alternator. When the engine is running, when each cylinder fires, the engine accelerates a tiny bit and then slows down before the next one fires. This gives a tiny ripple in the unregulated alternator output. The rev counter just counts the ripples. The output usually sits at about 6v - but you will need a sillyscope to see the ripples.

Si

So do the Ford and Land Rover alternator feeds work differently then? Any idea how they compare to the one from an EDIS unit (I'm hazarding a wild guess that will be pulsed - might have to ask on the Megasquirt forums)?

Wondered how on earth the tach could work effectively off the alternator!

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So do the Ford and Land Rover alternator feeds work differently then? Any idea how they compare to the one from an EDIS unit (I'm hazarding a wild guess that will be pulsed - might have to ask on the Megasquirt forums)?

Wondered how on earth the tach could work effectively off the alternator!

Jonathan said he put his DVM on the tach feed from the new alternator when we were figuring out the wiring, and it was giving a pulsed output - so was I right and Ford are using a pulsed tacho signal where Land Rover were using the slightly wavy 6V DC that Simon described? If so, the easiest fix is probably going to be to by the right alternator for the vechicle...tacho I can live without, suspension I can't!

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