Coil Voltage Problem

[Rstorrie]

My buddy is a ASE mechanic and said the coil is probably jacked and recommended changing it out even though it is new. Probably shorting in the windings or something internal. Got another coming tomorrow, we will see.

 

[Benny67]

My buddy is a ASE mechanic and said the coil is probably jacked and recommended changing it out even though it is new. Probably shorting in the windings or something internal.

Reading this post and I see you already swapped the coil out. ( Post #1)

Although, maybe you damaged it when you installed it?

Bench test the new coil....OR swap back the old coil and see what's up.

BTW...wellcraft, I like your troubleshooting technique...solid advice you're giving out..

 

[achris]

When the voltage at the coil drops to 8 volts, what is the voltage on the purple wire on the back of the key switch at the same moment?

If it's 12 volts, the problem is between the key and the coil. If it's 8 volts, the problem is before the key.

Also ensure your ground cables are as clean and tight as the positives.

Chris....

 

[nola mike]

Do the TB ignitions have a slave that supplies 12v to the coil while cranking?

 

[wellcraft-classic210]

Nola
Excellent point

I was wondering the same thing but have not taken time to study a print // I do know the start power to the coil on autos were supplied by the start circuit from the starter solenoid back when points were in use. Assume that's still the case but not 100% sure // And its not 100% clear when the measurements are being taken and how.

It could be a more than 1 issue at play.

 

[Benny67]

I didn't see anything about him confirming the ignition module being cleared for good health?

something might be up with it..

 

[achris]

Do the TB ignitions have a slave that supplies 12v to the coil while cranking?

No...

 

[wellcraft-classic210]

Looking at a post from DBDoctor apparently the key switch keeps power in the ignition wire (I) when in the the start position it also sends power to (S)

 

[Scott Danforth]

see line 3 of post #2

 

[wellcraft-classic210]

Scott
Thanks for clarifying that!