At what point is a High Idle switch a good upgrade.
Who makes it, whats it do?

Fast idle works for faster warmups in cold winter. If jump starting a vehicle, more RPM's = more amps. If idling down south, I've heard the A/C works better.
This is a good upgrade with LB7's and LLY's. Some of the later models have this feature built-in.
You don't need a switch. Only a wire and a crimp on pin for the ECM.
Eric sells the wire kit:
http://www.gmdieseltech.com/store2/cart.php?target=product&action=view&product_id=16137&category_id=248

LB7 instructions:
http://www.kennedydiesel.com/docs/HIGH%20IDLE%20INSTALL%20FINAL.htm

LLY instructions:
http://www.kennedydiesel.com/docs/Elevated_Idle_Description_LLY_Duramax.htm

Instead of wiring ECM connection to a +12V switch, connect wire to Stop Lamp Switch DK GRN/BLK wire. No switch will be needed.

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