David Jenkins
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| posted on 1/12/06 at 08:20 PM |
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Yet another VR sensor question!
According to the MJ instructions, it is essential that I get the polarity of the VR sensor correct. Fine - but I can't find anything that tells
me which is VRS+ and which is VRS-. All I know is, I have a sensor plug with 0.5 metres of shielded cable attached; in that cable there are 2 wires,
one of which is blue with a yellow stripe and the other is blue with a green stripe. Any clues?
I might even buy a length of cable and a new plug - they're cheap enough - but I would have NO clues then!
All help appreciated...
David
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paulf
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| posted on 1/12/06 at 08:51 PM |
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If you get the polarity wrong it will simply not spark , it will not do any damage, the easy way is to temporarily connect it and check operation .
Paul.
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omega 24 v6
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| posted on 1/12/06 at 10:51 PM |
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Strange one? I always thought that the VR sensor was working on the principle of creating an ac voltage (waveform) with a tooth missing to create the
trigger point. So I'd always thought the polarity would'nt matter as long as neither of the wires were connected to chassis ground.
If it looks wrong it probably is wrong.
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CairB
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| posted on 1/12/06 at 11:14 PM |
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With a VR sensor there is usually a positive and negative going pulse on the leading and trailing edges of the tooth.
Depending on the circuitry it could either not work, as I experienced with an EDIS4, or it could result in the timing being out by approximately the
tooth width.
On a Lucas RITA ignition system I used to have on a Triumph Trident reversing the polarity would change from having an advance with respect to speed
to a fixed angle.
[Edited on 2/12/06 by CairB]
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Dusty
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| posted on 2/12/06 at 12:38 AM |
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This is how ford wire the Crank Sensor plug.
 
Rescued attachment plug.jpg
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David Jenkins
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| posted on 2/12/06 at 09:05 AM |
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That's the sort of picture I was looking for - but now I'm really confused... you talk about "sens out" & "sens
earth", but the MJ wiring diagram has "+" and "-". Is "sens out" the "+" and "sens
earth" the "-"?
Everything I've read about the sensor emphasised that the connection should be right way around. As everything else will be new work(MJ,
wiring, EDIS & coil) I'd prefer to get as much right as possible to reduce the confusion when trying to start the car for the first time...
cheers to all,
David
[Edited on 2/12/06 by David Jenkins]
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CairB
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| posted on 2/12/06 at 10:03 AM |
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If you have a strobe light then I'd be tempted to spin the engine and check that the timing is in the right ball park.
When I first did my MSnEDIS I fitted the toothed wheel to a pillar drill, clamped the VR next to it and checked the system over with a strobe. I
gained confidence when I could see the effect of adjustments on the laptop.
Cheers,
Colin
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paulf
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| posted on 2/12/06 at 09:49 PM |
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Just found this , it may help.
Paul.
 
Rescued attachment ford_vr_181.jpg
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David Jenkins
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| posted on 3/12/06 at 10:13 AM |
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Magic! Ta muchly...
Sort-of says the same as Dusty's picture, but with recognisable terminology (coo - big words for a Sunday morning!)
[Edited on 3/12/06 by David Jenkins]
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David Jenkins
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| posted on 4/12/06 at 08:24 PM |
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Dur... must engage brain occasionally...
After all this - I took a look at the pieces of ignition kit I took off the donor car, and realised that the wires from the EDIS plug were still
attached. So, looking at the MJ wiring diagram, I could have worked out which VR wire was which...
...sometimes it is useful to fully engage the brain before coming onto the forum to ask a question! 
(Fortunately, the results do agree with the info given here!  )
cheers,
David
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.jpg)
