William's Gran Prix 1976 EM

The machine was gifted to a family member in a different city.
I don't have access to it until my next visit.

The current problem, I think, I foolishly didn't make a video,
is that when the ball falls into the top eject hole, the scoring motor starts and doesn't stop.
I think the bonus unit counts down correctly.

To prepare for my next visit and repair session, I am currently studying the schematics, and
this is how I interpret what I am seeing.

1. The ball falls into the top eject hole and closes the "top eject switch".
2. The closed "top eject switch" latches the "top eject relay".
3. The "top eject relay" energizes the "top eject coil", which kicks out the ball
and turns on the "score motor".
4. "Score motor" cam 4 switch D, "Make Break 4D", should pulse the "top eject coil" and
the left and right bonus score units.

If I remember correctly, the ball did not eject, so this is where I should look
first for a faulty switch.

If the ball does eject, I should check again to make sure the bonus score unit
zero position switch is working correctly. I think I already checked this.

Does that look right? Any other suggestions?

Does anyone have the equivalent of a "logic probe" that you hook up to relay contacts
to get a visual display of "energized"? Multimeter response seems slow for this.
I guess any 24v AC bulb would work.

Thanks paulace and @pinballdaveh. Very helpful. I'll checkout these
suggestions on my next visit to the machine.

One more question for you Grand Prix guys. I am studying the schematic to try and figure out
what the lock relay does. I see the coil on the schematic at D-4, but I don't see any switch anywhere
on the schematic that is labeled as "Lock Relay". It must be there, I just can't find it.
Thanks

Thanks so much, I just found that Game Over really on the schematic and now I see the Lock Relay switch
at C-17. Thanks @howardr.

Duh! I just noticed in your picture, but never noticed in my own copy of the manual,
that the switch location C-17 is listed right there next to relay. Learn something new
every day. Thanks again.

Back to the Grand Prix. Playfield removed. On player 1 ball 1, pressing start game button does not advance two players. Doesn’t look lik game is started. Any ideas what to check?

Back on site, for the first time in a while.
1. Still have motor running after game is in “game over”
2. Also, hanging wire in back box near 1st player scoring wheels
Black w orange stripes, see picture. Can anyone identify this
From their grand prix?

Thanks

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