1963/64 Cadillac Starting - Cranking System Basics

[Jason Edge]

I have had this info written up for some time and meant to post so here it is. I will link to this from our Help Page:

1963/64 Cadillac Starting - Cranking System Basics

Wiring
You have a positive cable from battery to the large bolt on the starter solenoid, a yellow wire from the (R) side of starter solenoid switch to the ignition coil, and a dark blue wire from the (S) side of solenoid to the Neutral Safety Switch, which in turn is fed by the purple(violet) wire from the ignition switch. There is a large ground strap from right frame rail to transmission bell housing bolt to engine block.  The frame is grounded directly by the negative battery cable which attached to the frame on the right side just in front of the radiator support under the battery tray.

The Neutral Safety Switch Prevents Cranking in “Drive” Gears 
The blue and purple cranking circuit is closed when the shift selector is in Park or Neutral, and open in any drive gear in order to prevent cranking the car in gear.
  
Starting - Cranking
With ignition switch turned to far right cranking position, the purple wire feeds the 12 volts to the blue wire at the neutral safety switch which feeds the starter solenoid switch. The yellow wire from solenoid switch in turn provides a full 12 volts back to the ignition coil for cranking. When you release the switch and have the switch in "run" position, the voltage to the coil is reduced to 8 1/2 to 10 1/2 volts since current is then  provided through the brown resister wire, which gets it's current at the pink ignition wire under the dash.  On the solenoid switch, the outer terminal away from engine is marked R and has the yellow wire connected. The inner wire is marked S and has the blue wire connected. The yellow wire is often dirty and hard to see the color and requires some cleaning.

Cranking Problems
One of the most important and overlooked components in the cranking circuit is the large ground strap that runs from the right frame rail over to the large bolt through transmission bell housing to engine and starter. If this is not connected and making good connection your starter will not work.   Check your ground strap and make sure it is making good connection.  If all other wiring is connected correctly, you could also have a bad ignition switch or melted and shorted ignition switch connector. Remove lower dash panel and disconnect the ignition switch connector and inspect closely with a light looking for melting and shorting. If all looks good, you can bypass the ignition switch and hot wire the car as noted below.
  
Hot Wiring
You can disconnect the large connector on the back of the ignition switch and hot wire the car by connecting the red (battery) to pink (ignition) wire and touching to Purple (starter).  I had a switch go bad on the way to a car show a few years back and made a quick 3 way jumper to hot wire the car. Here is a video showing how simple it is: https://6364cadillac.ning.com/video/hot-wired-ignition-switches
 
Bypassing the Neutral Safety Switch is Easy  
It is just a matter of unplugging the connector with the purple and dark blue wire and jumping the connector.  Be aware the car will now crank I any gear.

[Dennis P. DiBari]

Hi Linda,

     Accepted your friend request; thanks!  Like Jason, it sounds like the starter/solenoid with the starting issue (drawing too much).  That has been my experience over the years.  Replacing and cleaning the ground straps (even from heads to firewall) is critical.  I believe the starter/solenoid replacement may do it (fingers crossed).  You really went over everything.  Finding the charred wires by solenoid is great!  You are not the only one who likes things perfect.  Some of the cars in our Chapter are pristine.  If you can get the solenoid alone - try it.  Supposed to get cold across the country this week.  Do your best and keep us posted.  Best of luck.

Dennis DiBari

[Linda M. Brooks]

Thank you, I enjoy talking with you!  

Yes, I missed that ground strap.  It's cleaned up and ready to be installed, after I shine up the frame and bell housing, which didn't look bad, but glad I did it.  

Our cousin Bucky (used to run garage and parts stores) called my sister and asked how the car was coming.  We told him the whole sequence, including my slow turning starter at the BP, then the no shut off.  Anyway, he suggested removing the starter and having someone test it, or even if there is a rebuild shop around.  I had about an hour of daylight left and it was getting colder, so grabbed more tools and removed it.  He also said if I had jumper cables I could test it.  I was thinking that was a no-load test, but what the heck.  Positive battery to large solenoid lug, negative to starter body, then screwdriver across large + lug to S solenoid terminal.  I put my foot on it just in case, but it never spun or jumped.  Tried it twice, there was only a small spark when the screwdriver touched the S terminal.  Now he said I could tap it with a hammer to maybe get it to move, but I wouldn't trust it again so I didn't.  So, dead starter!  I will order one tonight and try for fast shipping to the motel.  Bucky thinks the starter failure also caused the ignition switch issue.  I sure hope so!  

We went out to the store for food for the next two days, and I got a pair of insulated boots to take the place of my ragged tennis shoes.  It has already started a snowy mix, and not sure how much accumulation will happen through Tuesday.  Would rather not go out if w don't have to.

So good news today, maybe we can head west Wednesday!  Thanks for the crossed fingers!  My poor Caddy isn't a show piece, but I love it.  I enjoy looking at other folks' work too!

Have a good night and will keep you posted!

Linda

[Dennis P. DiBari]

Hi Linda,

     You have made a lot of progress with the car being on the road.  I had a feeling that the starter/solenoid might do it.  When I did truck mechanic work and the truck wouldn't kick, I would always bring a hammer to bang the starter housing.  It was worth a try to get it started and then drove it to the shop.  The bench test that your cousin suggested is a good way to see if the solenoid throws the drive gear forward.  Hope the weather improves and you get it installed.  Anything for our Caddys!  Talk soon.

Dennis DiBari

[Chris McBride]

Did the replacement starter solve the problem?  

[Linda M. Brooks]

Reply to Chris (can't reply to his reply to me?):  I didn't order either of the only 2 M10 starters on-line from CA; I found a local alt/starter repair shop in Zanesville, OH, 5 miles from our motel.  Long story, will start a Post regarding what I have learned about Delco starters.  Sagle Auto Electric rebuilt the starter that was on my '64, but not without trouble because the starter that was on my car was a Delco M8 case.  It should have been an M10 starter.  Rex even painted the rebuilt one as I would, it looked great and we were on the road the next day!  Advice I would give to anyone owning our cars:  remove your starter during down time and find a rebuild shop.  Once the armature is damaged or too worn, the rebuild price goes up.  Also important to check that ground strap and clean up.  Very important to check the number on your Delco case.  More later on this, thanks for asking!

[Linda M. Brooks]

Made it to Montana on Nov. 19th with no other issues!  Had the old starter rebuilt, will post the ordeal I went through on that part.  May be valuable to others regarding the ACDelco case numbers.  I ended up having a 8M case vs. the 10M that came on the car.  The 8M parts will not work in a 10M, etc.  One of these days I'll find a used 10M and have it rebuilt.

Happy Thanksgiving!

Linda

[Dennis P. DiBari]

Hi Linda,

     Well done for sure.  Sent you a message on the internal website.

Dennis DiBari