re: no closer to finding out what it is.. Do the test Paul!! as below, with pump constantly running:-
The pinout on the CPS is a bit vague but pin 3 is the centre one. You shouldn't get a reading at all between the centre pin (3) and any of the other two but you show get between about 750Ω - 950Ω across pins 1 and 2. Your reading suggests to me that it is faulty. When testing for an output set the meter to the 200mV AC range and look for a pulse of quite a few tens of millivolts. 12µA means next to bugger all. Fiat crank sensors seem to have gone up in price a bit in recent years but still not too bad.
I don't think that wire has a problem. It provides an earth to the relay at power on and switches the relay so it must be intact. You should look at why there is power going to the pump at switch on but not the coils.
No, I didn't. Everything was 100% ok last time I rode it (about 2 weeks ago) and has been each and every time prior to that, so assumed that if the air gap was going out of tolerance I would have experienced some issues when riding it.
Thank you all for your help, I'm giving up for today as I feel I'm chasing my tail. I retested the CPS as per your suggestion above Derek (post #42) and now I get nothing at all in resistance between pins 1 & 2, or in fact between any combination of the pins. I've ordered a new CPS and when it arrives next week I will fit that, make sure the air gap is as it should be and then see if I have sparks at the plugs.
Good decision as you can easily get drawn into a rabbit hole,, if it's not the CPS then you can go back to the wiring
It's be good to do the same tests on your new CPS so you know what it gives when 'good'. Also, if your measurements match what you're getting from the old one it'll show you that your testing or method is suspect. Even better if you've got a mate with a storage oscilloscope instead of a multimeter so you can capture and measure the output.
The new CPS eventually arrived earlier this week but as it was a) my birthday on Tues last and b) SWMBO had taken the week off work (we were going to go away but plans were stymied due to Lockdown II), I haven’t had chance to have another go at this. Anyway, I did as @Chris suggested and have power at the coils when the RH relay is disconnected and the fuel pump is priming continually . Which is good, thanks Chris, no breaks in the circuit. I even bought myself a new multimeter just to ensure I’m not getting erroneous readings due to a fault with my cheapo old meter and I retested there’s continuity from terminal 87 of the LH relay to the coils snd yes there is. The new meter beeps. So, I test the old and the new CPS for resistance as per post #42 above. Nothing on either . It’s probably nothing (ha ha get it ) but I’d like to understand how to test a CPS for the future, just in case and I can’t believe the new one is faulty . Top CPS is the new one, meter is set to auto ohms. So I think I’m just going to fit the new CPS, connect up all the disconnected wires and press the street button. What could possibly go wrong
You should definitely get a reading across 2 of the pins. Try every combination for each CPS. Is that box from a Scrambler accessory I see there?
LOL, the box is yes, but no scrambler parts came in it, just a load of service items for my Monster and 748 from a Ducati dealer in Dublin, and you thought it was a set of Ducati Scrambler Beard Trimmers didn’t you I’ll retry various combinations of pins as I’m curious.
And she lives . Thanks to all who helped in the making of this thread . Put the new CPS in, reconnected everything that I’d disconnected, bar the plugs, turned her on, press the button, bingo, big fat sparks at the plugs . Put them back in and tried again, fired up first time. Thanks a million fellas.
Good to hear that the bike is running again Paul. You made massive job out of that but I'll bet you learned a lot too. I learned something too. Most of my experience with STs is with ST4s's which only have a fuel pump relay and a fan relay. But I found out that the 2 relays under the seat on the ST2 (and ST4) are in fact the fuel pump relay and the injection relay (switches the power to the ECU) and the fan relay is under the LH seat panel.
