how many ohms should an ignition module be?

  • Thread starter Thread starter Beck
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Beck

Volvo 240 ignition module - Does anyone know please what the ohm read out
should be on this module when not actually in the vehicle?

Our car has now broken down a couple of miles from home and will not start
at all. My Dad has bought the ignition module home with a view to testing
the connectors.

Despite a search on Google, I am having difficulty finding out what the
readings from pin to pin should be.

Results we have at the moment (with module out of vehicle) are the
following...

connecting between pins..

pins 3-4 = 2.1 ohms
pins 2-4 = 2.1 ohms
pins 1-4 = 4.6 ohms
pins 2-3 = 0 ohms (suspect)
pins 2-1 = 2.5 ohms
pins 1-3 = 2.5 ohms

As you can see, most pins are between 2-2.5 but with pins 1-4 being 4.6ohms
(excessive?) and pins 2-3 being zero.
 
Beck said:
Volvo 240 ignition module - Does anyone know please what the ohm read out
should be on this module when not actually in the vehicle?

Our car has now broken down a couple of miles from home and will not start
at all. My Dad has bought the ignition module home with a view to testing
the connectors.

Despite a search on Google, I am having difficulty finding out what the
readings from pin to pin should be.

Results we have at the moment (with module out of vehicle) are the
following...

connecting between pins..

pins 3-4 = 2.1 ohms
pins 2-4 = 2.1 ohms
pins 1-4 = 4.6 ohms
pins 2-3 = 0 ohms (suspect)
pins 2-1 = 2.5 ohms
pins 1-3 = 2.5 ohms

As you can see, most pins are between 2-2.5 but with pins 1-4 being 4.6ohms
(excessive?) and pins 2-3 being zero.
Click to expand...


It's kinda hard to tell much from ohm readings, you really need it to be
in an operating circuit to test it.
 
James said:
It's kinda hard to tell much from ohm readings, you really need it to
be in an operating circuit to test it.
Click to expand...

Just managed to get our hands on a new one to test and the readings are
significantly higher - in the 8-9 range. Perhaps the stalling problem is
the ignition module and its not serving enough power.
 
Just managed to get our hands on a new one to test and the readings are
significantly higher - in the 8-9 range. Perhaps the stalling problem is
the ignition module and its not serving enough power.
Click to expand...



I don't think you fully understand what you're measuring. The readings
could be different simply due to a different design of a circuit which
performs the same thing. Try the new one in the car and see how it
behaves, that's the only way to test it.
 
The repair manual I have (Bentley) gives readings, but only when the
vehicle is running.

Sort of a Catch-22.
 
James said:
I don't think you fully understand what you're measuring. The readings
could be different simply due to a different design of a circuit which
performs the same thing. Try the new one in the car and see how it
behaves, that's the only way to test it.
Click to expand...

No difference unfortunately, the car is still refusing to start at all now.
Thankfully we only borrowed it from someone :-)
 
Testing in situ gives the following recommended readings. (a) Terminal 4 to
ground and/or ignition coil terminal 15 should read 12Volts. (b) Terminal 5
to ground with starter motor operating should show a pulsating reading
between 0 and 2 Volts. (c) Terminal 1 to coil terminal 15 should read 0.6 to
1.2 Ohms resistance. (d) Terminal 1 to king lead connector on coil (HT
terminal) should read 6.5 - 9.0 Ohms resistance. (e) Terminal 2 to ground
should read 0 Ohms resistance. (f) Ensure that screen (shield) of screened
cable is connected to Terminal 3. If (c) reading is too low replace coil. If
(c) is too high, check wire between Terminal 1 and coil terminal 15, replace
or repair if necessary. If (d) is too low or too high replace coil. If (b)
is OK but unit is not working try replacement unit. The above information
comes from the EZ 116 K Ignition system Green Book.

All the best, Peter.

700/900/90 Register Keeper,
Volvo Owners Club (UK).
 
Beck said:
No difference unfortunately, the car is still refusing to start at all now.
Thankfully we only borrowed it from someone :-)
Click to expand...


What car is this and what condition is the wiring harness in? If it's
earlier than an '89 or so and the engine harness is original then that's
likely your problem.

Do check the hall sensor though.
 
James said:
What car is this and what condition is the wiring harness in? If it's
earlier than an '89 or so and the engine harness is original then
that's likely your problem.

Do check the hall sensor though.
Click to expand...

We think its possibly the fuel pump relay (its a 1993 volvo 240e). Symptoms
(car stalling on slowdown to junctions from a warm engine start) point to
fuel pump relay although the relay looks in very good condition. Going to
see if we can borrow one to test the car.
 
Beck said:
James Sweet wrote:




We think its possibly the fuel pump relay (its a 1993 volvo 240e). Symptoms
(car stalling on slowdown to junctions from a warm engine start) point to
fuel pump relay although the relay looks in very good condition. Going to
see if we can borrow one to test the car.
Click to expand...


Is the fuel pump running? You should be able to hear it under the car
while cranking the engine.

The outside of the relay can look fine and it can still be bad. You have
to pop the cover off and inspect the soldering on the circuit board.
 
James said:
Is the fuel pump running? You should be able to hear it under the car
while cranking the engine.

The outside of the relay can look fine and it can still be bad. You
have to pop the cover off and inspect the soldering on the circuit
board.
Click to expand...

We had a look at it last night, popped open the cover and it looked brand
new inside, no corrosion or anything. It was suggested that when the car
cut out, to place a wire between fuses 4 and 6 to see if the car would
start. If the car started it was probably the relay. It did start, but
unfortunately we do not know if it would have started anyway.
 
Beck said:
We had a look at it last night, popped open the cover and it looked brand
new inside, no corrosion or anything. It was suggested that when the car
cut out, to place a wire between fuses 4 and 6 to see if the car would
start. If the car started it was probably the relay. It did start, but
unfortunately we do not know if it would have started anyway.
Click to expand...
The failures show up as hairline cracks in the solder, running around the
leads for the relay connections. When I was young I could see them in any
light; now I have to take it into the sunlight and take my glasses off :-(

Mike
 
Michael said:
The failures show up as hairline cracks in the solder, running around
the leads for the relay connections. When I was young I could see
them in any light; now I have to take it into the sunlight and take
my glasses off :-(
Click to expand...

I was looking for corrosion :-(
If we do find hairline cracks, is it possible to just resolder it and be
done with it? Am finding it extremely difficult to find a replacement. One
company says they can get one but it will be a 6 week delivery. We need a
fix now as the car is getting steadily worse.
 
Michael Pardee wrote:
Click to expand...
I was looking for corrosion :-(
If we do find hairline cracks, is it possible to just resolder it and be
done with it? Am finding it extremely difficult to find a replacement. One
company says they can get one but it will be a 6 week delivery. We need a
fix now as the car is getting steadily worse.
Click to expand...

Yes, resoldering is the recommended alternative to replacement.


Gary
 
Beck said:
Michael Pardee wrote:




I was looking for corrosion :-(
If we do find hairline cracks, is it possible to just resolder it and be
done with it? Am finding it extremely difficult to find a replacement. One
company says they can get one but it will be a 6 week delivery. We need a
fix now as the car is getting steadily worse.
Click to expand...


Yes, it takes about 5 minutes. Just heat up the joints with a soldering
iron and flow in a bit of fresh rosin core solder, then let it cool. Any
TV repair shop can do it for you if you lack the tools to do it yourself.
 
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