MSD wiring to tach adapter

[DynaBro]

Tach does not work. Red and white wires off tach adapter PN 8920 go to nothing.

White wire off MSD 6A PN 6201 go to nothing.

Any ideas?

 

[coloradodave]

For your viewing pleasure: https://www.mpsracing.com/instructions/MSD/8920.pdf

 

[DynaBro]

For your viewing pleasure: https://www.mpsracing.com/instructions/MSD/8920.pdf

NICE.

 

[DynaBro]

Actually 6AL and my 6A wiring don’t jive.

 

[DynaBro]

And the best coming from the MSD is going nowhere as well.

 

[Billccm]

Troubleshooting video and theory.

Restoring Tach for 68 Road Runner – Project BeepBeep

 

[kiwigtx]

And the best coming from the MSD is going nowhere as well.

Maybe some visual aids might be in order here......

 

[DynaBro]

Ok so I connected the White to the White, and the Red from the tach adapter to the Gray form the MSD. Nothing. Then I left the Gray bare and connected the Red from the tach adapter to a hot fuse box. Still nothing.

 

[DynaBro]

Got it sorted. Tach works and I’m pretty happy. One victory. Tuesday the oil pump is on deck.

 

[coloradodave]

Got it sorted how? The answer might help the next guy...

 

[DynaBro]

Got it sorted how? The answer might help the next guy...

The gray from the MSD went to the white from the tach adapter. I ran the red from the adapter along the firewall to the other side of the engine bay and mated it with two other thick red hot wires mounted to the small lower block left of the master cylinder. I’m hoping that’s the same as splicing it into an ignition wire. Anyway it worked.

 

[coloradodave]

DynaBro, May I humbly suggest that you invest in a multimeter and a Factory Service Manual so you don't have to guess whether or not your wiring is going to ignite and burn your car to the ground? Also, complete MSD instruction and installation manuals are available online at the Holley site. I don't mean to upset you, but would hate to see another Mopar fried and you having to rely on Shank's Mare to get around...

 

[RemCharger]

When in doubt, hook some wires to other wires and see if something happens.

 

[DynaBro]

I looked and looked for my model no luck. There’s a major difference between the 6A and the one linked above (6AL I think). Mine has no dedicated “to tach” wire and I extrapolated based on other MSD diagrams and their usage of gray to white. The hot wire was pretty easy to determine. Plus I remove my battery wires when the car is not in use. There wasn’t a lot of options for me to even try given the undedicated wires available. But you did get me thinking and I got a line tester light and discovered I had it linked to a constant hot. I found a hot lead at a fuse box the old owners wired in for the MSD that only goes live when the ignition is on and switched it over.

 

[kiwigtx]

When in doubt, hook some wires to other wires and see if something happens.