MSD Diode placement

[Amstaff]

Can someone school me on where to wire in the diode that keeps the car from having "run on" after the ignition is shut off?

[Amstaff]

Nobody?

[Amstaff]

Searched the forum but doesn't seem like anyone got an answer, at least not one that was public.

[juanbenae]

im not aware of such a thing. which MSD model do you have? narrow it down some for us.

[rbogh901]

I have vague recollection that MSD specifies this somewhere in their own support. Let us know if you find it.

[Amstaff]

Originally Posted by juanbenae

im not aware of such a thing. which MSD model do you have? narrow it down some for us.

It is the MSD 6425 6AL

I understand that it is a fairly common thing to have engine run on. The unit came with the diode but instructions for placement were for GM, Chrysler etc.

[Amstaff]

Bump-a-saurus Rex

Alt light stays on which I understand is the problem. Anyone know which wire that is?

[86 911 Targa]

https://www.google.com/search?sourceid=navclient&ie=UTF-8&rlz=1T4GUEA_enUS570US570&q=MSD+6425+6AL
^^^^^
Hope this helps.

Gerry

[Amstaff]

The link just goes to units for sale.

[timmy2]

Page 8 & 9 diode installation instructions or
Install a resistor on the switched power lead.
http://www.g3ignition.com/images/MSD%206%20Series%20Installation%20Instructions.pdf

[86 911 Targa]

Originally Posted by Amstaff

The link just goes to units for sale.

Please have a look at the links located at the very bottom of the page...

Gerry

[T77911S]

never heard of putting in a diode for anything ignition related.

not sure what you mean by runs on.

I remember our car did that as a kid. we called it dieseling and heard the engine runs backwards when it it did it. it was a dodge aspen from either the 70's or early 80's

[Amstaff]

Since installing the MSD box when I turn the key off the car just continues to run. Not sputtering but just running as normal until the car runs out of fuel. Apparently the box gets power from or through the alternator that gives the MSD box power to continue to allow the car to run.

[al lkosmal]

I just went thru this with my last AEM install.

Directions I received for how to install the diode.

On the diode, the easiest place to install it is directly behind the speedo at the alternator light. You want the cathode (stripe on the diode) on the alternator side of the blue wire. The side without the stripe should be closest to the light. This will prevent current from “leaking” out of the alternator through this wire.

Note: to make installation easy, I crimped faston connectors to the diode, so i could unplug the blue wire and plug the diode in.

See below for a couple schematics:

[Amstaff]

Awesome!!

Thank you

Originally Posted by al lkosmal

I just went thru this with my last AEM install.

Directions I received for how to install the diode.

On the diode, the easiest place to install it is directly behind the speedo at the alternator light. You want the cathode (stripe on the diode) on the alternator side of the blue wire. The side without the stripe should be closest to the light. This will prevent current from “leaking” out of the alternator through this wire.

Note: to make installation easy, I crimped faston connectors to the diode, so i could unplug the blue wire and plug the diode in.

See below for a couple schematics:

[T77911S]

where did you connect the switched power for the MSD and where did you connect the constant power for the MSD?
if you used the original switched power that went to the CD then you should not have an issue.

it could be your ign switch. does anything else stay on?

I have put in 2 MSD's and never had this issue

[Amstaff]

I put the constant power to the starter and the switched power to one of the fuses in the engine compartment

[T77911S]

looks like one fuse is hot all the time and the other 2 are switched power.

you have found the one that is hot all the time,

I got a connector that mates with the factory one. that way I can plug in my bosch CD if the MSD goes bad