I have an MSD unit and also purchased a new engine compartment wire harness for american auto wire...They set the harness up to wire to the MSD unit where the wire from the MSD unit goes to the keyed source, they gave me two wires a pink and yellow. In talking with them they said to connect the pink and yellow wires together and then connect to the red keyed wire from the MSD unit. This worked perfectly until today when I installed my gauge cluster (speedometer and fuel gauges) into the dash. When I plug the plug into the back of the gauges, I loose the keyed source or in otherwords I can not turn the motor off. I have to disconnect the wires. When the plug into the back of the gauges is not plugged in, the motor will turn on and off like it is suppose to with the key.

Does anyone have this setup or maybe know what could be causing this? I do have the plug, plugged in correctly, I have checked that 3 or 4 times...

you have a back feed install a diode in series to the guages power plug

Does this need to be on the gauges plug or on the new wires to the MSD? Where can I get a diode from? How would I install it and to which wire?

Does this need to be on the gauges plug or on the new wires to the MSD? Where can I get a diode from? How would I install it and to which wire?
50 volt diode 10 watt available at radio shack
what color wires do you have in guages plug?
wire in series to guages plug wire that loses power when key turns off (plug not connected) note- observe correct polarity

There are 12 wire slots on the although all are not used. 1 - 6 on top and 7 - 12 on bottom...Here is the colors connected to each

1 Brown
2 Green (double wires)
3 Grey
4 nothing connected
5 nothing connected
6 nothing connected
7 Red
8 Dark blue
9 Light blue
10 Light brown
11 Dark brown
12 Dark blue

When you say wire in series, I would assume you mean to splice this into the wire? Also in which direction would the polarity go?

Thanks for your help.

check this off the msd site: http://www.msdignition.com/1troub1.htm#runon

That is what I need...it says that it should connect to the brown wire from the alternator. I do have a brown wire coming from my alternator plug so I would guess that this is where the diode should be connected. there are two wires that plug into the alternator. One is red and the other is brown...does anyone know what these wires are used for or their function in the circuit? I know there is a thicker red wire too, but I am referring to the two wires that are plugged into the alternator with an internal regulator...

The color codes are different than stock because of the internal reg alternator, but the brown one feeds the gen light, that's the one that gets the diode. The red one is the "Remote voltage sense" line and should connect in the main splice of horn relay.

I added the diode to the brown wire as indicated, however my gen light stays lite up when the motor is running...I am wondering if it could have anything to do with adding the diode? I know the diode is installed correctly as far as direction, and the car turns on and off with the key again...Any ideas why the gen light on the dash would stay on?