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[Mk2] [Turbo] 3 pin plug on alternator - 0v on one pin - where does wire go?

 
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toecutter




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1992 Toyota MR2 Mk2 Turbo Rev2

PostPosted: Sat Dec 15, 2012 4:18 pm    Post subject: [Mk2] [Turbo] 3 pin plug on alternator - 0v on one pin - where does wire go? Reply with quote Reply with quote including images

Rev 2 Turbo

Car is not charging battery, checked 3 pin plug with ign on, found one pin to be at 0v (think it is black and yellow wire nearest the floor).

Where does the wire go? Looks like it goes into the loom at the intake manifold. Is there anywhere it usually breaks?
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Peter Gidden - SBITS
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PostPosted: Sat Dec 15, 2012 6:05 pm    Post subject: Reply with quote Reply with quote including images

It goes to fuse ECU-IG. Breaks in the loom.
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Nick Bryant




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1995 Toyota MR2 Mk2 Turbo Rev3

PostPosted: Sat Dec 15, 2012 8:17 pm    Post subject: Re: [Mk2] [Turbo] 3 pin plug on alternator - 0v on one pin - where does wire go? Reply with quote Reply with quote including images

toecutter wrote:
Rev 2 Turbo

Car is not charging battery, checked 3 pin plug with ign on, found one pin to be at 0v (think it is black and yellow wire nearest the floor).

Where does the wire go? Looks like it goes into the loom at the intake manifold. Is there anywhere it usually breaks?


It goes up to the fuse box in the engine bay fella, its the top white plug (EB1) that has 2 black and yellow wires, you should have continuity between one of them, if memory serves me I think it was the thickest out the 2 wires.

I hope that helps.
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toecutter




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1992 Toyota MR2 Mk2 Turbo Rev2

PostPosted: Sun Dec 16, 2012 12:48 pm    Post subject: Reply with quote Reply with quote including images

I have continuity between pin on plug for b/y wire on alt to the plug in fusebox on the thick b/y wire. But I'm only getting 0.4v at the alternator plug.

How do I get to the bottom of the fuse box? Have taken brackets and clip off but its held by something, can move it enough to see underside.
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Peter Gidden - SBITS
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PostPosted: Sun Dec 16, 2012 1:09 pm    Post subject: Reply with quote Reply with quote including images

toecutter wrote:
I have continuity between pin on plug for b/y wire on alt to the plug in fusebox on the thick b/y wire. But I'm only getting 0.4v at the alternator plug.


So just to clarify, with ignition on, you're getting 12V at ECU-IG fuse, but only 0.4V at the alternator end of the black/yellow wire?

If so, your issue is inside the loom. Just bypass wire - problem sorted.
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toecutter




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1992 Toyota MR2 Mk2 Turbo Rev2

PostPosted: Sun Dec 16, 2012 1:30 pm    Post subject: Reply with quote Reply with quote including images

Across the terminals of ECU-IG fuse I'm only getting 0.2v, so break must be further up.

Where does the wire end up from from the fuse box, looks like the loom goes into the cabin at the end of the fuel tank?
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Peter Gidden - SBITS
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PostPosted: Sun Dec 16, 2012 2:31 pm    Post subject: Reply with quote Reply with quote including images

toecutter wrote:
Across the terminals of ECU-IG fuse I'm only getting 0.2v, so break must be further up.


"Across"? [Confused]

Measure voltage with one voltmeter earthed, and the other on the point you're measuring.
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toecutter




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1992 Toyota MR2 Mk2 Turbo Rev2

PostPosted: Sun Dec 16, 2012 2:50 pm    Post subject: Reply with quote Reply with quote including images

Yeah realised that after I had done it [Embarassed] still not getting 12v to it though.

There is continuity between all points there should be after the plug on base of fuse box, so problem must be further back. Only wiring diagrams I can find are in japanese, do you know where the wire leads to in the cabin? Assuming thats where it goes if it stays with rest of loom.
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Peter Gidden - SBITS
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PostPosted: Sun Dec 16, 2012 3:40 pm    Post subject: Reply with quote Reply with quote including images

So with ignition on, the live side of fuse ECU-IG is dead??? I've never known that. And if it is, the car won't run.

ECU-IG fuse is fed directly from the ignition main relay, that also feeds the coil etc.
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toecutter




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1992 Toyota MR2 Mk2 Turbo Rev2

PostPosted: Sun Dec 16, 2012 4:01 pm    Post subject: Reply with quote Reply with quote including images

It's getting about 0.2v, tried earthing in a few different places, same anywhere I try. Car has been running just won't charge.
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Peter Gidden - SBITS
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PostPosted: Sun Dec 16, 2012 4:13 pm    Post subject: Reply with quote Reply with quote including images

In that case, i don't understand. ECU-IG fuse is fed directly from the ignition main relay. And that also feeds the coil etc. So if no output from relay, no working engine. Simples.

Have you checked the fuse?
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toecutter




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1992 Toyota MR2 Mk2 Turbo Rev2

PostPosted: Sun Dec 16, 2012 4:21 pm    Post subject: Reply with quote Reply with quote including images

Yeah fuse is fine.

Just checking ignition relay, according to BGB the should be continuity between pins 1 and 3, my meter dosent beep, shows 68 ohms between them. Could this be the issue? But with power on the relay, it does what it should as described by bgb.

It still starts, sounded like it was running on 3 cylinders for first 20 secs or so. Idles a bit rough as well. Don't know if this is related or not.
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Nick Bryant




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1995 Toyota MR2 Mk2 Turbo Rev3

PostPosted: Sun Dec 16, 2012 8:58 pm    Post subject: Reply with quote Reply with quote including images

Have you got access to a different multimeter just for comparison as like Peter says, if your not getting 12v at the ECU-IG fuse then it 100% will not run as there will be no spark going to the cap.

Have you checked the 7.5amp alt sensing fuse in the front fuse box?
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toecutter




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1992 Toyota MR2 Mk2 Turbo Rev2

PostPosted: Sun Dec 16, 2012 9:19 pm    Post subject: Reply with quote Reply with quote including images

Can get a shot of one but mines reading fine on anything else I try.

Ay that fuse is fine to.

Will need to check eveything again but already went round everything a few times and it was the same.
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Nick Bryant




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1995 Toyota MR2 Mk2 Turbo Rev3

PostPosted: Sun Dec 16, 2012 9:29 pm    Post subject: Reply with quote Reply with quote including images

Can I ask if you can start right back at the beginning?

How did you come to the conclusion that the alternator is not charging?
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toecutter




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1992 Toyota MR2 Mk2 Turbo Rev2

PostPosted: Mon Dec 17, 2012 7:30 am    Post subject: Reply with quote Reply with quote including images

yeah will have to do that.

as the car died on way to work, wouldn't restart. Had someone bring a fresh battery out to me and that got me to work. the 3 warning lights are on all the time. charge battery every night. battery is fine.
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Paulhilluk




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1992 Toyota MR2 Mk2 NA Rev2

PostPosted: Sat Aug 10, 2013 10:51 am    Post subject: Reply with quote Reply with quote including images

I have this problem in the alternator loom and I am about to bypass as suggested in this thread. Does anyone have a drawing of the fuse box, mine has no illustration on the back of the box and I can't seem to find a drawing anywhere.

Also, how far into the loom does the breakage usually occur? I have the weekend free and might splice the loom [Confused]
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toecutter




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1992 Toyota MR2 Mk2 Turbo Rev2

PostPosted: Sun Aug 11, 2013 9:18 am    Post subject: Reply with quote Reply with quote including images

My problem wasn't with the wiring, I had forgotten to disarm the imob. after switching on ignition when testing the wire [Brick wall] and as such there was no voltage because imob. cut it.

Problem was the alternator rectifier.

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auzzam
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1993 Toyota MR2 Mk2 Turbo Rev3

PostPosted: Sat Sep 24, 2016 4:56 pm    Post subject: Reply with quote Reply with quote including images

Did anyone have any luck on this...

Experiencing the same issue, my ECU ign only gets 0-1v at the fuse box.

My other two wires on the alternator plug are getting the correct current. Just the black and yellow one thats giving the issue.
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auzzam
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1993 Toyota MR2 Mk2 Turbo Rev3

PostPosted: Sat Sep 24, 2016 5:30 pm    Post subject: Reply with quote Reply with quote including images

Like a numpty I too tested the wire when the imoboliswr was off!!!

So all the cables are fine which points towards the alternator.
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