When fitting the new battery have you failed to connect the LT lead.

On the positive side you have a thick HT lead and normally a thin LT lead sometimes they are in the same connector and sometimes they are seperate if you have not connected this lead it would account for all your troubles.

There are NO other cables that i missed. I checked thoroughly, there is a large connector for the Pos side with one fuse and three small square boxes with a pastic moulding around the whole lot and multiple cables leading from the bottom of it.

i have checked this fuse and it appears to be intact

Edited by surge0n66 on 01/08/2010 at 15:47

Hi. Here we are, back at the start of the thread really, I have checked the plug and - no spark, I checked the coil HT (No output, but I have TWO coils and one is brand spanking new!) I thought therefore that the fault must be the input into the coil, hence the question.... what is next up the electrical ladder from this stage, points or cdi/ecu......

strange, it was running fine until I put the new battery on, thats why I thought there may be an impact electrical cut off/immobiliser that may be reset.......

Oh for an electrical system schematc. Surely I couldn't just go POS battery to coil without the ECU/CDI unit in the middle.......it cannot be that simple.......

Edited by surge0n66 on 01/08/2010 at 17:23

That is a very interesting reply, many thanks for the insight. I will try that tomorrow, I take it this would not suffice as a permanent fix?

Your replies are very much appreciated, Thanks

Edited by surge0n66 on 01/08/2010 at 19:09

You seem to have got yourself in a bit of a knot here. The ignition coil has two terminals. One is marked + or (15). This is coil positive and comes directly from the ignition switch and will be a 12V supply. Check that 12 volts are present by connecting your red voltmeter probe to this terminal and your black probe to the negative battery terminal when the ignition is switched on and with the engine cranking. If you do not get 12 volts then you have a problem with the live feed to the coil. If you do not have 12 volts you could test by using a jump wire straight from the battery positive to coil positive and see if you get a spark.

The other terminal is marked - or (1). UNDER NO CIRCUMSTANCES MUST YOU CONNECT A DIRECT BATTERY FEED TO HERE. DOING SO WILL CAUSE A SHORT CIRCUIT IN THE ECU AND PERMANENT DAMAGE MAY RESULT. This is coil negative and is switched on and off by the ignition module or ECU. Connect your red meter probe onto this terminal, select volts and crank the engine. What you should get is a switch between 12 volts and 0 volts as the coil switches. In reality you won't see that because a digital voltmeter cannot react fast enough to the change. Instead what you will see is is less than 12 volts depending on your meter. To measure correctly you need a meter with duty cycle function that will check dwell, Hz, % or duration in milliseconds. You could use an LED test lamp which will flash as the engine cranks, but it's often difficult to tell whether the light is flashing or continuously on because the coil switches several times per second, especially in bright sunlight. If the coil is not switching then the ECU, ignition module or crankshaft sensor may be at fault.

Try these tests if you can and post back your findings.

Edited by Railroad. on 01/08/2010 at 23:22