I am working on an automotive project where we are using an LED as an indicator for the operation of an engine cooling fan, which is turned on and off automatically by the vehicle's ECM.
The module that activates the fan receives ground as an activation signal, so we connected the ground source of the LED to the wire that activates the module and the hot wire of the LED to a power source on the vehicles fuse box. The problem is that the LED remains lit in a low dim at all times and it only turns brighter when the ECM activates the cooling fan.
We tried installing a relay but the actions reverse and only the LED turns on, but not the cooling fan; is there a simple solution for this?
Thanks in advance.