well that's good news in a way then Paul? could have been an ECU failure etc. A bit premature, but make sure it's Cuban if possible
Not out of the woods yet @Chris . @Derek Definitely no corrosion on the relays under the seat. Checking again, and there’s no voltage to the coil at key on. Disconnect LH relay, key on, pump primes won’t stop priming. Reconnect LH relay, disconnect RH, no priming of pump. Swap them over, try again, same thing. I’m pretty sure both relays are functioning as they should. Haven’t done a continuity test yet, as a) I need to research how to, b) I’m not sure my cheap multimeter can do that having just read the instructions c) SWMBO has plans for me TTFN
The sensor should measure 860Ω ± 10% measured across pins 1 & 2 of it's connector. Pin 3 is a screen. Look out for any visible swelling of it's housing which is usually an indication of failure or imminent failure. Flicking a magnet or even a spanner or any lump of iron/steel across the end of it should produce a pulse at it's output. Although it will be small and very short it should produce a flicker of some sort on a DVM set to read 200mV ac.
Something weird there. With the relay disconnected (unplugged) the pump shouldn't run at all because removal of the relay completely breaks the circuit.
This is an academic question but what I can’t understand/work out from the wiring diagram is why the pump doesn’t switch off? The RH relay operates the fan. I disconnect the LH relay the pump doesn’t prime. I disconnect the RH relay the pump primes but doesn’t stop priming. Both relays connected the pump primes for about 3 secs then stops as it should. Makes no difference if the relays are swapped over. I don’t want to disappear down a rabbit hole but as said, I can’t see from the wiring diagram why the RH relay should have any affect upon the pump. Also, @Derek please, what do you mean by pin 87?
I can't tell you why the pump doesn't stop but pin 87 is one of the relay connectors, they are standardised numbers for the connectors and should be marked on the base of the relay. You have pins 30, 85, 86 and 87 on a 4 pin relay, 87 should be the one that is 90 degrees to the others
First of all, as said, carefully check that you have the correct wiring diagram for your bike Paul, as subtle changes over the years can confuse the issue. Hopefully with correct diagram you can cross-reference with the wire colours you see on your bike to confirm this, and can then work out the intended circuitry. As Harry said (terminal) "87" is moulded into the relay base (the underseat one) and any decent wiring diagram will have terminal numbers displayed.
Although I can't explain the continued power to pump in above test (it would appear that intact circuit via RH relay is needed as verification within ECU before correct overall function) I would tend to use this to test power to coils. If circuitry is indeed as per diagram, and you are showing no current at brown/white wire at coils (or injectors) when set up as above, then you must have a break in the wire route from pump to same.
What year is your ST2 Paul? There are 2 different wiring diagrams for the ST2 that I'm aware of, those with single phase alternators up to 1998, and bikes from 1999 onward with 3-phase alternators. Although there may be some detail changes for different years the injection wiring for all of them (and the ST4) remains the same. Unlike the later ST4s and ST3, the ST2 and ST4 which use the IAW16 ECU additionally have an injection relay, which is the one shown in the diagram I posted in thread #16. I've never had an ST2 although I've worked on a few but I cannot remember the location of each relay. There are 2 side by side and another further back under the LH side panel. The wire colours to each should identify which is which. I suspect that the 2 side by side are the fuel pump relay and the injection relay. No matter. The fuel pump is supplied with 12V by the relay when the relay is activated. The same 12V should also go to the injectors and the coils since they are all supplied by the same brown/white wire from the relay pin 87. Since the pump runs continuously when the RH is disconnected then the fuel pump relay must be being switched on. Now the relay can only be switched on when it is grounded by the ECU through the other brown/white wire from pin 85 of the relay to pin 23 of the ECU. Removing the RH relay removes the power from the ECU so you'd think that the ECU wouldn't switch the fuel pump connection to ground but this may be a red herring. I think you should concentrate on continuity through the brown/white connecting the fuel pump relay to the pump, coils and injectors.
Just a very long shot Paul - you can easily discount this, was bike fitted with an alarm? I saw a non-std earth wire and connection on one of your pictures, and wondered if you might have a few odd "piggyback" type connections elsewhere, like pump feed for example.
I don't know Chris? It has no written history, just verbal from the fella I bought it from although he seemed honest enough. He didn't mention any alarm at all. Where's the non-standard earth you spotted?
I just went online to buy a CPS £156.17 . I'm off now to find a Lancia/Fiat/AN Other make from the car world that'll be a fraction of that price I guess.
First picture on this thread, over to the left, bolted on top of a brown wire which also has an aftermarket ring terminal. It’s a skimpy black wire with two tails, just the sort that the aftermarket alarm brigade use.
Ah, it looks like 2 tails, one cut off but actually that piece is just electrical tape coming unstuck, not a cut wire, just the angle of the photo. It is an aftermarket ground, one I put in when I installed a set of LED DRLs on the front to save me having to have the front lights on and thus to allow more power flow to the reg/rec for the battery due to this being a weedy 420w alternator. The fatter brown wire is the earth for the reg/rec which is a newer aftermarket one the previous owner had fitted when the OEM one gave up the ghost.
I found the numbers for the relay terminals inside the relay, thanks fellas, I never knew that . Assuming I’m using my multimeter correctly and having learned how to use it to measure for continuity (thanks to YT), connecting pin 87 of the relay to the brown white wires at each coil I get continuity . Also, armed with @Derek 's instructions of how to test the CPS (thanks Derek) and with the knowledge they were £156 (I now know there is a much cheaper alternative - thanks again Derek) I went back and retested the CPS. I'm not sure which is pin 3, whether it's the middle one as marked in there (which seems illogical) or one of the end ones but connecting the middle pin (which despite the marking I think of as pin 2) and the one to its left I get a reading which varies with each attempt from 120Ω to 70Ω, the middle pin and the right hand pin give nothing. With the MM on the middle and left pins, passing a piece of metal in front of the CPS magnet gives me a current of 12µA, thus I'm now assuming the CPS is not actually faulty but is functioning - which appeases the logicality of my brain as I just can't get my head around why it would be OK one minute and not the next when it's not been used. For the sake of £20 though I'm still going to order a new CPS, it can always be kept as a spare. So, good news on the CPS but I'm no further forward in finding what the fault is.
Next I check continuity from pin 85 on the relay (i know what these pin numbers are now and how to check continuity so I'm gonna use my new found knowledge ) to pin 23 on the ecu. This is the orange/black wire that grounds the injector/ignition relay to the ecu. If I've interpreted the wiring diagram correctly pin 23 on the ecu is the top row, 4th connector (5th slot) from the right. Nothing Now I'm thinking, if that's the problem a) how could it have just broken? b) how can I trace it without pulling apart the entire loom, and c) I need a cup of coffee
