Grant Baker Posted April 14, 2018 Report Share Posted April 14, 2018 Hey guys, Just fitted an S15 plugin to a PS13 Sylvia. All pins doing as they should etc, but losing 12v to ECU on cranking. Seems that Pin 38 (ECCS 14v Relay) is losing power on cranking. Is this normal on the PS13? Pin 34 is starter signal Pin 36 is Ignition Signal and is live when cranking. Should we swap Pin 38 & Pin 36? Quote Link to comment Share on other sites More sharing options...
Grant Baker Posted April 14, 2018 Author Report Share Posted April 14, 2018 Added a 12v supply to pin 38. This didn't fix it... Power is being lost to the ECU even though 12v at ECU now... Any ideas? Quote Link to comment Share on other sites More sharing options...
Grant Baker Posted April 14, 2018 Author Report Share Posted April 14, 2018 And as another addendum, it’s actually comms that are being lost, rather than voltage. So why would ecu power down / drop comms while cranking? Quote Link to comment Share on other sites More sharing options...
ClintBHP Posted April 14, 2018 Report Share Posted April 14, 2018 If you have 14v all the time then it much be either an earth issue OR you are inducing too much magnetic noise, a good test for this is to bump start it, if that works then look at the starter. Quote Link to comment Share on other sites More sharing options...
Grant Baker Posted April 14, 2018 Author Report Share Posted April 14, 2018 Have you seen comms lost with poor earth? Quote Link to comment Share on other sites More sharing options...
ClintBHP Posted April 14, 2018 Report Share Posted April 14, 2018 Yes I have seen it twice, both times the earths had been spliced into one and were screwed to a poor ground point (one ground point was painted and one was rusty) , supplying battery voltage direct solved the problem. Quote Link to comment Share on other sites More sharing options...
Grant Baker Posted April 14, 2018 Author Report Share Posted April 14, 2018 Awesome. Thanks. Never had this before. Voltage on pin 38 *was* going from 12.4v-10.9v-9.6v-7.7v-5.4v-3.3v. So an earth issue may also make sense. What is a little odd is that it ran fine on stock ECU. Quote Link to comment Share on other sites More sharing options...
Adamw Posted April 15, 2018 Report Share Posted April 15, 2018 The main grounds are on Pin 39&48, and the main 12V supply is on pin 38 & 47. Try an aligator clip jumper lead direct to battery to isolate which one of these pins is disappearing when cranking. Note these two grounds and two power pins are linked together internally so you only need to test one of each. Quote Link to comment Share on other sites More sharing options...
Grant Baker Posted April 16, 2018 Author Report Share Posted April 16, 2018 Right, the plot thickens... Jumped the power and earth cables. Definitely the +12v rather than earth. However, as soon as the engine cranks, the laptop loses comms still! Engine runs and purrs away, but comms gone. Just about to try a different laptop and comms cable. Will report back. Quote Link to comment Share on other sites More sharing options...
Grant Baker Posted April 16, 2018 Author Report Share Posted April 16, 2018 OK... Not laptop or comms cable. Any bright ideas fellas? Quote Link to comment Share on other sites More sharing options...
Grant Baker Posted April 16, 2018 Author Report Share Posted April 16, 2018 Tried a 3rd laptop... problem sorted... Actually incredible that this turned out to be the issue. Very very weird. Quote Link to comment Share on other sites More sharing options...
ClintBHP Posted April 16, 2018 Report Share Posted April 16, 2018 Try bumping it with one of the laptops with the issue, I bet its fine, will be magnetic interference from the Starter. Quote Link to comment Share on other sites More sharing options...
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