Remote Start Anti-Grind

How do you guys create an anit-grind circuit if the RS unit does not have it built in.

I know I can use the starter kill relay for this but I don't know where to get a constant power (-) or (+) only when the RS is active. I was thinking of the TACH if there is enough to power a relay but then that will always be active when the engine is running and not only in RS mode.

Why don't car manufacturers make this a standard feature?

Thanks LittleBill, I have to find a similar wire on my RS unit.

try doing this - for the anti-grind, tie a wire from your relay providing power to the coil, to pin 85 of a new relay, then wire pin 86 of the new relay to your alternators field wire.  when your relay provides power for the coil, it will energize the new relay, and you should route your starter relays power thru the new relay.  bah - i'll draw ya a diagram.....

A = your existing remote start coil power relay

B = your existing remote start starter motor power relay

C = New anti-grind relay

how it works - when the engine is not running, the field wire on the alternator will provide the ground necessary to activate relay C when there is power applied to the coil by relay A.  that will complete your starter circuit to the way you have it now, but - once the engine has started, the alternator field wire will change to a + output.  since there will be + on both 85 and 86 of relay C, the relay will shut off,  breaking the circuit so that relay B cannot be energized again until such time as the engine dies.   by the way, just about any general purpose diode will work, and you have to have it.  if you just wire it without the diode, the field wire could provide enough power thru the relay to keep your engine running (though not completely likely, i have seen it happen).  hope this helps

or you can just use one relay in a starter kill/anti grind configuration, have it done in 5 minutes and get the customer out the door 

b