Thread: No Spark - Electrickery basics

Have you checked the resistance across the terminals on the dizzy that the amp wires into - I think it should read between 2k and 5k ohm

Ignition on test

1. Between Batt - and Batt + should be more than 12v
2. Between Batt - and Coil + max of 1v less than 1 above
3. Between Batt - and Coil - max of 1v less than 1 above
4. Between amp ground and earth Max 0.0 - 0.1v

If coil and amp is suspected faulty, disconnect LT at the coil repeat test above, if voltage / readings are still incorrect new coil, if the volts/readings are now correct - check LT lead/wire - if satisfactory - new amplifier

Thanks for the reply Ladas.
the pick up tests ok, the ignition on tests are all OK. Which LT lead do I remove, + or neg. The result for Test 3 is the one that confuses me,
"Connect voltmeter between Battery positive (+) and HT coil negative (-) terminal, voltmeter should read 0volts. " I get 12.5volts, it doesn't say what this result means
The rest test out OK, changes to 0 volts with ignition on and reading increases when cranking, which indicates that the amp is getting a signal from the pick up, it then says to proceed to test 5 , HT sparking, No spark for me. And from test 5 I should fit a new coil and retest.
Does this make sense?? I'm not keen on buying as new coil if it's not the issue.
Should there be any resistance across the pos and neg of the coil, I'm getting 0 ohms.

If it is a standard 95 disco my pick would be the ignition module as it cooks on the side of the dizzy. Could also be the rotor button - particularly if it has been replaced by a non-genuine item.

Gazzz

Originally Posted by garrycol

If it is a standard 95 disco my pick would be the ignition module as it cooks on the side of the dizzy. Could also be the rotor button - particularly if it has been replaced by a non-genuine item.

Gazzz

Thanks Gazz, it's the Lucas 35DM8 dizzy, with the remote amp near the coil was factory fitted to some discos I'm lead to believe. Also, no spark from the coil HT lead, so not even getting to the dizzy

Originally Posted by Discobunny

Thanks for the reply Ladas.
the pick up tests ok, the ignition on tests are all OK. Which LT lead do I remove, + or neg. The result for Test 3 is the one that confuses me,
"Connect voltmeter between Battery positive (+) and HT coil negative (-) terminal, voltmeter should read 0volts. " I get 12.5volts, it doesn't say what this result means
The rest test out OK, changes to 0 volts with ignition on and reading increases when cranking, which indicates that the amp is getting a signal from the pick up, it then says to proceed to test 5 , HT sparking, No spark for me. And from test 5 I should fit a new coil and retest.
Does this make sense?? I'm not keen on buying as new coil if it's not the issue.
Should there be any resistance across the pos and neg of the coil, I'm getting 0 ohms.

I don't think you should see any resistance across the + and - LT on the coil. (IF any it would be very small)

You are not going to loose anything if you test with the + LT on the coil removed - the amp is still in line. After that test with the - LT removed and the + LT replaced.

Do you get any resistance on the amp wires (amp disconnected)

However if you do not have a spark @ the HT lead (disconnected from Dizzy (held 6mm off engine block) then it leads me to suggest a poor coil

Originally Posted by Discobunny

Thanks for the reply Ladas.
the pick up tests ok, the ignition on tests are all OK. Which LT lead do I remove, + or neg. The result for Test 3 is the one that confuses me,
"Connect voltmeter between Battery positive (+) and HT coil negative (-) terminal, voltmeter should read 0volts. " I get 12.5volts, it doesn't say what this result means
The rest test out OK, changes to 0 volts with ignition on and reading increases when cranking, which indicates that the amp is getting a signal from the pick up, it then says to proceed to test 5 , HT sparking, No spark for me. And from test 5 I should fit a new coil and retest.
Does this make sense?? I'm not keen on buying as new coil if it's not the issue.
Should there be any resistance across the pos and neg of the coil, I'm getting 0 ohms.

i think that should read coil positive +ve.........you are checking for voltage drop in this test between the battery and the coil.....
or....in english....checking for bad connections.....