MSD Install - No power at switched +

rickster2 · 02-21-2008, 02:29 AM

Installing a MSD 6AL into my '86 911 turbo which was running fine with the stock Bosch system. Installed MSD per MSD and Pelican BBS instructions using male spades into the 6-pin connector and find that the + switched wire is not getting power.

Mounted the MSD where the old CD box was.

While testing I did get 12 volts from the + red switched terminal "intermittenly" with key is on position and the defog relays plugged in. Now I cannot get any power from the switched terminal. Shook the wire harness thinking that it could be a shorted wire but still no power. I can't imagine that the defog relays have anything to do with it.

I've got plenty of fuel in the engine but no spark. I connected the red MSD wire to a constant 12 volt source and the car will start. What would prevent the switched red wire from getting power and what could I have done to change that?

DME relay????

Thanks

wachuko · wachuko's Garage

A friendly bump...

Just curious, if the Bosch system was working fine why would you install an MSD??

I got and MSD sitting in my garage (brand new) that I got when I my car died... Turned out to be a bad coil so I never install it... in my case the cost of getting another CD vs an MSD made the choice simple... but again, since the stock stuff was fine that is what I am still using.

Rich Lambert · Rich Lambert's Garage

Don't know if this applies to your year car, but when I installed the MSD in my '66 I followed the instructions and the car wouldn't start. Turns out the wire they want hooked up for switched (+) power is only hot when the key is in the start position.

Eagledriver · 02-22-2008, 10:21 AM

You need to trace out your wiring problem. It may be that your dashboard ignition switch is bad. The electrical part of it can be replaced separately from the mechanical part.

-Andy

jluetjen · jluetjen's Garage

Why did you mention the defog relays? It makes me think that you tapped into a wire that is not always on when the ignition is on. In my '69, Porsche had a tap in the back left corner of the engine compartment that was always hot (12V) when the ignition was on. That's what I used.

911Freak · 02-22-2008, 10:38 AM

Yep, I used a simple circuit tested to find the "always hot" terminal on the block on the lower left of engine.. However I ran my own main + line from the starter..the switched (thin red line)+ is from terminal 15 in the plug for the CDI unit

rickster2 · 02-22-2008, 12:38 PM

Thanks for your replys.

I had unplugged the two relays (#4-heater blower relay and 5- rear defog relay) that are on top of the engine compartment fuse box to aid in installing the MSD. I did not think they were necessary for testing. I plugged them back in while trying to find the reason why the switched + was not getting hot. Out of coincidence, the switched + was hot for a short period, but then, dead again.

Must be a short somewhere around the relay plug wiring.