[SOLVED] Simple switch trigger?

I'm trying to add a switch that controls two seat warmers at once. I know I need two diodes to isolate the new circuit so the old switches don't trigger themselves.

Anyways here is the problem I'm having.

I hooked up a lead to one switch, and when I touch the lead to the chassis ground it's just like I'm pressing the switch, so perfect. BUT when I add on the diode (yes I know they have a direction) it no longer works, what could the diode be doing to cause it not to work?

Do I need to add a capacitor? the diode is interfering somehow, I just don't understand what it's doing. I know the voltage drops from 4.7 to 4.4 and the amps drop from 0.9 to 0.8 when the diode is inline.

I thought a diode simply allowed current to flow through, but I think the voltage drop is causing the circuit not to identify "my switch", how do I compensate for the diode? capacitor? my electronics knowledge is limited. Thanks.

Without a schemtic it's pretty difficult to answer your question. You don't say where you're 'adding on the diode'