dnmalc
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| posted on 9/5/08 at 06:32 PM |
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Testing Vauxhall Ignition units
I have a single overhead cam 1600 with no spark. I have been told that the fault is either the ignition pack or the crankshaft sensor (or of course
any of the wiring in between). As the ignition pack is on the end of the camshaft this is wher i started However this has 4 inputs.
one is the earth which is OK,
one is the 12v input which is OK.
the other two come from the control unit and I assume are a digital input. My questions are
1. are these 2 wires a digital input
2. is there a simple way to test this input with my multimeter
3. If the fault is not (2) is there a simple way of testing the coil
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theconrodkid
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| posted on 9/5/08 at 06:35 PM |
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them systems are normally pretty bullet proof apart from the cps,you can check that by waving a screwdriver or similar over the end of the can and
checking for aprox 0.5 volts AC at the wiring terminals
who cares who wins
pass the pork pies
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tks
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| posted on 9/5/08 at 07:55 PM |
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basicly the 2 pins wich you have found are the coils ends...
and you should measure there 12volts as wel.
If you don't measure 12volts the coil is broken.
An Ignition coild works like a magnetic field. by connecting it accros the battery it charges this is time it takes to charge, its called the dwell
time. Its a unique value (property) per coil and per termperature...
wich states for the time needed to charge to give a optimum voltage. watchout for to high dwell times it damages your coil!!!
so if you want to test a coil just strike the wire of the positive and don't let it connected.. we are talking in the order of miliseconds...
when the coil is connected to ground (on one side) and to the battery a current starts to flow and a magnetic field is created (like always on every
coil) on the moment when you disconnect it. The magnetic field collapses and changes its direccion. (yes effectifly generating a bit of AC voltage!!)
because of the relation ship between the 2 internal coils (like in a transformator) it generates a very high voltage and that voltage is given to the
sparkplug.... wich becomes the spark.
So in effect your coilpack hasnt got outputs nor inputs. its just a util wich you can connect to an MCU. In effect its an actuator and you need an
output wich sinks (current) on your mcu.
to test the coilpack you need to find the positive pin and the other end of its internal coil (wich has a resitance in the order of couple of ohms 1
to 3ohms.
you say you found a pin wich is ground....
this is strange since a coilpack is grounded by the mcu (one pin per coil)
its possible they have a common plus. or just per coil a plus (positive terminal)
so if you have 4 pins.. put your multimeter in the lowest ohm position and search for a combination of pins wich gives you a value of 1 and
3ohms...
hope you can untherstand it...
p.s.!! a coil is a sensitive device and because it is sensitive and the mcu expects it to be in 100% condition a touched coil can produce nasy
thing...
so checking an coil is very diffcult and you cant tell by if its broken until your engine runs fine on it.
1)search for the 2 pins wich gives about 1 and 3ohms
2)search for the second set of pins wich gives about 1 and 3 ohms..
2b) if you cant find the pin set wich gives you a low ohmage its broken!!
3)hook the coil up to battery voltage and strike the negative terminal against ground.. every time you losen it it should spark. don't touch it
to long best bet is to just strike it past
4) if it sparks it could be that its in good shape..
5) if it don't sparks its surely broken...
in the coil can be filled up with oil and that takes allot of heat... if you blow it up you can burn yourself badly!!!!
Tks
The above comments are always meant to be from the above persons perspective.
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dnmalc
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| posted on 9/5/08 at 09:50 PM |
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Thanks TK for the info but a lot of that seems to be associated with a traditional coil.
The problem I have with the Vauxhall unit is basically because rather than them being supplied with a simple interupted 12 v supply they have (I now
learn) two coils which use a wasted spark system so the extra 2 connections seem to be associated with switching the 12 V supply I have already found.
This switch sypply I assume is then fed to each of the coils and then down to ground.
Thus the 2 other inputs are not digital as i had suspected. But these seem to be modulated analogue inputs that I assume to be driving some
transistors that gate the 12 volt supply These transistors being necessary so that the MCU does not suffer the voltage spikes that it would see with a
traditionally interupted 12v supply.
If my thoughts are correct the problem of testing this system is that the two MCU inputs appear not to be the ends of the coils. Thus testing the coil
is not simple a continuity check or striking the battery through it as i am concerned that this could fry the transistors. I suppose I could strile it
with a 1k resistor in series and so limit the current. Any thoughts??
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tks
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| posted on 10/5/08 at 08:11 AM |
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if the 2 input pins are inputs and connect the coil to ground...
you would need to measure a voltage border arround 0,6volts.... thats the typical border for a transistor.
so connect your multimeter in diode setting and connect the red unit to the that pin (input) and the black one to ground.
You should see on your display a value...
i doubt this is the case though....
because normalyy all the electronics are keeped central and that means in the mcu unit...
so i don't thik you are right on your thoughts... but you could be any way....
how much pins does the thing have?? 4???
and you suspect one common ground one positive and 2 trigger inputs...
it could be.... but i don't think its right..
Tks
[Edited on 10/5/08 by tks]
The above comments are always meant to be from the above persons perspective.
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dnmalc
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| posted on 12/5/08 at 05:27 AM |
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Thanks TKs. The haines manual shows clearly that the unit is connected to ground and to the 12v supply via the ignition with the extra 2 wires from
the MCU. There is no simple route to ground via the MCU so no earthing in that direction and at the moment no apparent 12v but this could be due to a
duff CPS.
Thanks for thoughts though
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MikeRJ
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| posted on 12/5/08 at 09:19 AM |
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The coil pack simply has two coils in it. The primaries of both both coils are commoned at the +ve igntion connection, and the two wires to the ECU
ground the other sides of the primaries. The ground connection on the plug is probably for a built in suppressor or screening to prevent
interference,
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