Anfurnyy Posted July 16, 2023 Report Share Posted July 16, 2023 Having issues with my Auxillary outputs working to control my fans, and secondary fuel pump. I'm using Aux 5-8 (previously the ISC outputs to the throttle body) to control 2 fans that are powered via relay. All The outputs are configured as: Fan 1 & 2 Polarity: High Drive High Using Hella 40amp sealed relays for fans and a 35amp micro relay for the fuel pump. I verified: the relays are getting 12+v (13.5v measured) on from battery source on pin 30 Getting 12.25v from the output from ECU on pin 86 when set to "Test On" Verified good ground continuity (.2ohms) at the fan ground AND relay ground. Pin 87 on the relay never outputs the 12+v from the battery at the connector for the fans. If I run the switched 12v directly to battery source it activates and the fan turns on. Is it possible that the ISC motors output can push enough to activate the relays? Would I instead have to configure it as low so it pulls the relay to ground? Quote Link to comment Share on other sites More sharing options...
Confused Posted July 16, 2023 Report Share Posted July 16, 2023 Unless specifically mentioned, the ECU ground switches every output, and if you're using them for other purposes, I would suggest that you use them as ground switched. I'm Nlnot sure what the ISC outputs Aux 5-8 do differently, but I suspect that's only valid when in ISC mode? Quote Link to comment Share on other sites More sharing options...
Adamw Posted July 16, 2023 Report Share Posted July 16, 2023 Most plug-in ecu's dont have the high side drives on aux 5-8, so they will not have enough grunt to drive a relay high. You will need to change the wiring so that the ecu is switching the ground side of the relay coil. Quote Link to comment Share on other sites More sharing options...
Anfurnyy Posted July 16, 2023 Author Report Share Posted July 16, 2023 Thank you both, I will get it rewired for ground switching and go from there Quote Link to comment Share on other sites More sharing options...
Anfurnyy Posted July 17, 2023 Author Report Share Posted July 17, 2023 So I got the relay wiring switched to switched ground however when I key the engine off, both fans turn on and stay on until I either disconnect battery or turn the key to "on" I'm assuming the ISC outputs are pulled to ground when the key is in the off position? I did verify that the engine fan RPM zero timeout was set to 1 or 0 seconds. Quote Link to comment Share on other sites More sharing options...
Confused Posted July 17, 2023 Report Share Posted July 17, 2023 You must power the relay's coils from a switched 12v feed. Anfurnyy 1 Quote Link to comment Share on other sites More sharing options...
koracing Posted July 17, 2023 Report Share Posted July 17, 2023 7 hours ago, Anfurnyy said: So I got the relay wiring switched to switched ground however when I key the engine off, both fans turn on and stay on until I either disconnect battery or turn the key to "on" I'm assuming the ISC outputs are pulled to ground when the key is in the off position? I did verify that the engine fan RPM zero timeout was set to 1 or 0 seconds. Yes the outputs end up at ground when the key is off on all the Aux1-8 outputs. If you have Aux 11-16 available they do not do this, however. Quote Link to comment Share on other sites More sharing options...
Anfurnyy Posted July 17, 2023 Author Report Share Posted July 17, 2023 8 minutes ago, koracing said: Yes the outputs end up at ground when the key is off on all the Aux1-8 outputs. If you have Aux 11-16 available they do not do this, however. I don't think this plug n play has those outputs. I've only got 1-8 unless I'm misunderstanding the software pinouts. Quote Link to comment Share on other sites More sharing options...
koracing Posted July 17, 2023 Report Share Posted July 17, 2023 No, most older designed bottom/adapter boards won't take advantage of the additional possible outputs. Not sure at what point the extra 10 pins were added to the plug-ins that include the 2nd CAN bus and the 11-16 aux outputs, but I've seen several plug-ins that don't have a socket on the adapter board for using these - including the VR4 Link. Only using a switched 12v supply for the trigger positive (pin 85) is the best bet in your case. Quote Link to comment Share on other sites More sharing options...
Anfurnyy Posted July 17, 2023 Author Report Share Posted July 17, 2023 18 minutes ago, koracing said: No, most older designed bottom/adapter boards won't take advantage of the additional possible outputs. Not sure at what point the extra 10 pins were added to the plug-ins that include the 2nd CAN bus and the 11-16 aux outputs, but I've seen several plug-ins that don't have a socket on the adapter board for using these - including the VR4 Link. Only using a switched 12v supply for the trigger positive (pin 85) is the best bet in your case. I got switched 12v applied to pin 85 and it works as intended now. Thank you guys a ton for helping! Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.