I am having problems with an old (H reg) Vauxhall Cavalier. Basically it
won't start - there is no spark. These have a fairly basic electronic
ignition system which consists of a hall-effect unit in the distributor, an
electronics control module, a darlington power transistor amplifier and a
coil. What I need to check first of all is if there is any output from the
hall-effect unit, but I have no means of doing this. Anyone got any ideas
about signal levels coming out of this, etc, or any other ideas about checks
I can make without much in the way of test equipment?

On Mon, 9 Jan 2006 13:56:22 -0000, "Barney"
wrote:

I am having problems with an old (H reg) Vauxhall Cavalier. Basically it
won't start - there is no spark. These have a fairly basic electronic
ignition system which consists of a hall-effect unit in the distributor, an
electronics control module, a darlington power transistor amplifier and a
coil. What I need to check first of all is if there is any output from the
hall-effect unit, but I have no means of doing this. Anyone got any ideas
about signal levels coming out of this, etc, or any other ideas about checks
I can make without much in the way of test equipment?


I have a hall effect pickup on my truck's speedometer. It is three
wire. Has +5 volts to one terminal, ground on the other and the
middle wire varies from +5 to ground as the rear wheels turn. It is
on the differential. Identical device on the drive shaft (anti-skid
input?)
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default wrote in message
...
On Mon, 9 Jan 2006 13:56:22 -0000, "Barney"
wrote:

I am having problems with an old (H reg) Vauxhall Cavalier. Basically it
won't start - there is no spark. These have a fairly basic electronic
ignition system which consists of a hall-effect unit in the distributor,
an
electronics control module, a darlington power transistor amplifier and a
coil. What I need to check first of all is if there is any output from
the
hall-effect unit, but I have no means of doing this. Anyone got any ideas
about signal levels coming out of this, etc, or any other ideas about
checks
I can make without much in the way of test equipment?


I have a hall effect pickup on my truck's speedometer. It is three
wire. Has +5 volts to one terminal, ground on the other and the
middle wire varies from +5 to ground as the rear wheels turn. It is
on the differential. Identical device on the drive shaft (anti-skid
input?)
--

Yes this is three wire too, but with a 12 volt supply - I think they usually
have a voltage regulator, so that the supply voltage can be anything from
about +3 volts to +24 volts. If the output is roughly a square wave from 0
to +5 volts I should be able make a simple tester for it quite easily.

Many thanks.

On Mon, 9 Jan 2006 15:00:37 -0000, "Barney"
wrote:

Yes this is three wire too, but with a 12 volt supply - I think they usually
have a voltage regulator, so that the supply voltage can be anything from
about +3 volts to +24 volts. If the output is roughly a square wave from 0
to +5 volts I should be able make a simple tester for it quite easily.

Nice thing about it is you can slowly turn the engine and watch it
turn on and off with a meter or use a magnet . . .

No reason it can't be a 12 volt switch. My truck is old and the speed
sensor just goes into the "computer" which probably has a 5V regulator
built in.
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default wrote in message
...
On Mon, 9 Jan 2006 15:00:37 -0000, "Barney"
wrote:

Yes this is three wire too, but with a 12 volt supply - I think they
usually
have a voltage regulator, so that the supply voltage can be anything from
about +3 volts to +24 volts. If the output is roughly a square wave from
0
to +5 volts I should be able make a simple tester for it quite easily.

Nice thing about it is you can slowly turn the engine and watch it
turn on and off with a meter or use a magnet . . .


That's an excellent idea. I don't need any kind of a tester - I can just
take out the spark plugs, and then use your method of turning the engine
over slowly and measuring the output with a meter.
Cheers.