TomD Posted October 20, 2020 Report Share Posted October 20, 2020 Finalizing my install in a 95 M3 US, so basically an M50 harness. Will be a turbocharged platform. I am looking for an aux output for boost control. Looks like Aux 7 is available as I do not have TCM because it is a manual gearbox and Aux-ign 8 as I no longer have the canister or purge valve. I'm having difficulties sorting a connection without hacking up the factory harness. No TP/TCM lead on my harness. Soliciting suggestions. 1. Does it matter which one I use? Is one more suitable for PWM control of a boost valve than the other? 2. Suggestions on the physical connection, tap into the ecu harness plug? If it doesn't matter in the above question, use the purge valve lead since it has a connection to the ECU? 3. If I do not use Aux-ign 8/Purge I do not see an option to turn it off in PCLink. Do I leave it alone? Unassign or reassign to something that allows it to be turned off? 4. Just to confirm, one lead from the boost control valve goes to the Aux output and the other to switched 12v source. Thank you for any help. Quote Link to comment Share on other sites More sharing options...
Adamw Posted October 20, 2020 Report Share Posted October 20, 2020 5 hours ago, TomD said: 1. Does it matter which one I use? Is one more suitable for PWM control of a boost valve than the other? In theory Aux 7 would possibly work better as it has a flywheel diode attached so the valve action will more closely follow the commanded DC. But I have successfully used ign drives for boost control before too so it is likely minimal difference. 5 hours ago, TomD said: 2. Suggestions on the physical connection, tap into the ecu harness plug? If it doesn't matter in the above question, use the purge valve lead since it has a connection to the ECU? If there is already a wire there that is never going to be used then it would be common practice to just snip that wire and splice your new wire on to it. Or you may be able to buy a new terminal, remove the old wire and insert the new one. The big terminals are Junior timer (easy to get), the small terminals are micro timer I (more difficult to get), and the small ones are a real challenge to extract from those connectors unless you have done it before. 5 hours ago, TomD said: 3. If I do not use Aux-ign 8/Purge I do not see an option to turn it off in PCLink. Do I leave it alone? Unassign or reassign to something that allows it to be turned off? Go to >Auxiliary Outputs>Purge, double click where it says Ign 8 and change it to none. 5 hours ago, TomD said: 4. Just to confirm, one lead from the boost control valve goes to the Aux output and the other to switched 12v source. Correct. Quote Link to comment Share on other sites More sharing options...
TomD Posted October 21, 2020 Author Report Share Posted October 21, 2020 Thank you for the help. I'll get to know the software, I promise. Quote Link to comment Share on other sites More sharing options...
Papajon2.0 Posted September 22, 2021 Report Share Posted September 22, 2021 So I can just tap into the stock harness for my boost control solenoid and it will work!?!? Like say my evap plug? Quote Link to comment Share on other sites More sharing options...
Adamw Posted September 22, 2021 Report Share Posted September 22, 2021 Answered in your other post. Quote Link to comment Share on other sites More sharing options...
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