1999 SC2 remote start, tachometer

Ok, so i instralled a Code Alarm CA425 / CA545 into my gf's SC2.  The wire identification sheet said

I used that one and the alarm can't sense the tach input. 

Now the instructions say that to test the wire you do this:

1. Set voltmeter to AC VOLTS. 

2. Attach positive lead of a volt meter to a constant 12-volt source.

3. Attach negative lead of a volt meter to the wire to be tested.

4. start the engine.

5 have someone press on tthe gas pedal slightly as you monitor the meter.  If connected to the correct wire, the voltage reading will increase as the engine's RPM increases.

Now i did the following and the voltage did change, but it was only about .1 at idel and about .4 at about 3-5k rpm. 

Is that wire not the right wire, which wire is it in the pcm.  I know it has to be at the pcm, and its so much easier to get it from there.  thanks guys

Try the white wire at the ignition module on top of the motor.

Got another problem, in the wiring diagram it said that the door pin wire was under the ash tray.  I found a white wire there that would show (-) when the pass door was open but not the driver.  I probed around and found a wire that would always show (-) when the driver door was open.  So what i did, was i used two IN4001 diodes and hooked it up in exactly this way (below) .  The problem now is that i no longer have a door chime at all.  I can leave the light on and nothing, i can leave key in inginiiton and nothing.  Once in a while it sound like it tries to chime but merely sounds like very faint clicks (not like relay clicks).  Why did this now work.  ????