1999 jeep cherokee, alarm/remote start

I have a situation with the rear defroster, There a 4 wires behind the defroster switch.  I tested each to find out which one gave me 12v when I turn the switch on and I connected to it with a relay.  Now the defroster doesn't  when you turn it on from the switch in the car but the switch lights up when I push the ch5 button on the remote.  I don't think it's working from the remote just lighting the switch up.  Can anyone tell me what I did wrong.electronics

1999 jeep cherokee with rs 860electronics

ok, I have the rs 860 installed on the 99 jeep cherokee everything is working fine except the check engine light stays.  When it's on remote start and when I turn it on with the key.  I powered up both ignition wires but  I noticed the 2nd ign wire when testing only gives 12v  in the on and not the start.  The first ignition  when turning the key, is powered up on and start but the 2nd powers up just on on.  During remote both power up at on and start but the check engine stays on even when the key is in after stepping on the brake to disengage remote start. Any suggestions or is there a way to reset the check engine light?  electronics

 Everything is working fine.  Could not find the tach wire with proper reading so I went with voltage sensing, works fine.  The check engine light was sending false signals had that reset.  The only thing I need to  know is how to connect the rear defrost to alarm remote.  Thank if anyone can help.electronics