wiring msd ignition

[rickyg7354]

whats going on everyone, i have a 86c10 and putting a 383 into it. i am trying to wire up the msd ignition but having issues finding a 12v ignition source. normally this would be the distributor wire correct? however i can seem to decipher which one that is; i got the truck as a roller. there is a pink wire coming from the fuse block on the driver side but its dead. any help would really be appreciated. pretty stumped on this one.

 

[nvrenuf]

My 91 Blazer had some unused spots towards the upper right corner of the fuse block that were open, I tapped one for my fuel pump relay.

 

[Scott91370]

The wiring diagrams here will show what each wire in the bulkhead do. And yes, it should be one of the pink wires. Second row from bottom (#3) in my diagram below. The other pink is fuel gauge.

https://www.gmsquarebody.com/threads/1973-1991-wiring-manuals.14498/

This is the 85:

You must be registered for see images attach

 

[nvrenuf]

Just to say it…. MSD likes a clean signal so try to find an unused circuit. If you piggyback something in use it MAY cause interference and drivability issues.

 

[rickyg7354]

My 91 Blazer had some unused spots towards the upper right corner of the fuse block that were open, I tapped one for my fuel pump relay.

this is what i found yesterday and i think ill be doing the same for the msd

 

[rickyg7354]

The wiring diagrams here will show what each wire in the bulkhead do. And yes, it should be one of the pink wires. Second row from bottom (#3) in my diagram below. The other pink is fuel gauge.

https://www.gmsquarebody.com/threads/1973-1991-wiring-manuals.14498/

This is the 85:

You must be registered for see images attach

thanks for this, i figured it was the pink but for some reason its a dead wire. the other pink one i have has constant 12v even with the key off. kinda odd

 

[Bextreme04]

thanks for this, i figured it was the pink but for some reason its a dead wire. the other pink one i have has constant 12v even with the key off. kinda odd

I would get a cheap waterproof relay box from Amazon or similar and use a different ignition signal(like the original wire to the HEI) to trigger the relay on. That way you get a clean, full battery power, signal to the MSD that isn't affected by all the power loss and voltage spikes it can get from going through all the old wiring and switches.

I'm currently using this one in my truck for electric fan, electric choke, trailer power, etc... and it works well.
https://www.amazon.com/dp/B0BX6LDR3B/

There is also something like this that would be easier and a bit smaller... lots of options on Amazon for various pre-wired(or not) fuse and relay boxes that are waterproof.
https://www.amazon.com/dp/B0BY7MGR78/

There are also things like this painless kit.. but it isn't waterproof and probably shouldn't be mounted in the engine bay.
https://www.amazon.com/dp/B000VTUB4A/