SchuKingR Posted April 6, 2020 Report Share Posted April 6, 2020 Hello! I've got a problem with my Link Thunder ECU that I installed in my 93 JDM S6 FD RX-7. I made an adapter, so my Thunder is installed in the OEM loom like a Link plug-in ECU. I can't get the A/C request to work with the Thunder. The Thunder don't recognise it, when I press the A/C button. I saw, that there was some kind of similar problem with some plug-in ecus. What can I do to make my A/C work? Cheers, Toni Quote Link to comment Share on other sites More sharing options...
Adamw Posted April 6, 2020 Report Share Posted April 6, 2020 Can you measure the voltage on the AC request wire with the switch on, off and with the fan in different positions. Quote Link to comment Share on other sites More sharing options...
SchuKingR Posted April 6, 2020 Author Report Share Posted April 6, 2020 yes. I will try that on the weekend and post my results here then. Quote Link to comment Share on other sites More sharing options...
SchuKingR Posted April 11, 2020 Author Report Share Posted April 11, 2020 Good Morning Adam (here in Germany it's 11:30am). I measured the voltage yesterday. AC on Fan 0/same as AC off 12,1V AC on Fan 1 1,65V AC on Fan 2 2,03V AC on Fan 3 2,67V AC on Fan 4 2,67V all was measured with car not running, but charger on battery. Found this old thread: sounds like the same problem with an old ViPEC and a S7 FD RX-7. My Thunder ECU should be fairly new. I bought it last year black friday from an German Distributor. Quote Link to comment Share on other sites More sharing options...
Adamw Posted April 11, 2020 Report Share Posted April 11, 2020 The switching threshold on the digital inputs is about 1.2v, so it’s not going to work when your voltage is always above 1.2v both on and off. I’m pretty sure the plug in ecu has a couple of diodes in series to lower the voltage. I’ll check tomorrow and see if I can come up with a suggestion. SchuKingR 1 Quote Link to comment Share on other sites More sharing options...
SchuKingR Posted April 11, 2020 Author Report Share Posted April 11, 2020 Just looked at the PCLink G4X Software. There it's possible to set a virtual aux AC request source. If something like this would be possible for G4+, then I would set the AC Request wire to an analog voltage input and specify the voltages to engage it. I think Haltech works similar to that. There you can set the on and off voltage for the digital inputs. Couldn't this be added to the firmware for G4+ as well? Quote Link to comment Share on other sites More sharing options...
Adamw Posted April 11, 2020 Report Share Posted April 11, 2020 If you had a spare Aux out you could do your analog input trick. Connect an aux direct to a DI with a wire link. Then set up the aux output to turn on when analog input is below say 3V. The FD plug-in ECU has a zener diode and pull-down resistor added to bring the voltage down. An easy option maybe to put 3 x silicon diodes in series with your DI, this will drop your voltage by about 2.1V. SchuKingR 1 Quote Link to comment Share on other sites More sharing options...
SchuKingR Posted April 12, 2020 Author Report Share Posted April 12, 2020 hmm the analog input trick should work as a workaround for now. with the diodes: won't there be the same problem as in the thread mentioned above? "When AC pressure switch(in series w AC button) is open due to high pressure, voltage @ pin 4V is 0v=gnd. This means that Vipec ECU does not understand that AC systempressure is to high and just keeps running the AC compressor." Quote Link to comment Share on other sites More sharing options...
Adamw Posted April 12, 2020 Report Share Posted April 12, 2020 I suspect the DI pull-up is meant to be on so it should go to 12V when the pressure switch is open. Did you do your voltage tests above with the pull-up on or off? If pull-up was off, can you do another test with it on to see how different it is. Quote Link to comment Share on other sites More sharing options...
SchuKingR Posted April 18, 2020 Author Report Share Posted April 18, 2020 hey Adam. I measured the voltages again today. You were right, first measure was with pull-up off. Now I measured it again with pull-up on, but with exactly the same voltages. It wasn't recognised by the ecu, like without the pull-up. I try to get me some diodes to test it with them. Quote Link to comment Share on other sites More sharing options...
SchuKingR Posted August 13, 2022 Author Report Share Posted August 13, 2022 On 4/12/2020 at 12:35 AM, Adamw said: If you had a spare Aux out you could do your analog input trick. Connect an aux direct to a DI with a wire link. Then set up the aux output to turn on when analog input is below say 3V. The FD plug-in ECU has a zener diode and pull-down resistor added to bring the voltage down. An easy option maybe to put 3 x silicon diodes in series with your DI, this will drop your voltage by about 2.1V. managed to put 3 diodes in series with the DI. Now I got AC working at fan stage 1, but at no other stage. Will address this later, when renewing the whole wiring. Stage 1 AC is better than no AC Quote Link to comment Share on other sites More sharing options...
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