Gain extra benefits by becoming a Supporting Member Click here find out how!
Classic Performance Products Classic Parts
Ciadella InteriorsAmerican Auto Wire Classic Industries
Chevs of the 40sDanchuk Catalog
Hellwig Products IncPerformance Rod & CustomEcklers AutoMotive
Nu-Relics Power Windows
Impala Bob's Bob's Chevy Trucks Bob's Chevelle Parts Bob's Classic Chevy



Username Post: Key on and start 12v        (Topic#349142)
lowblazer 
Forum Newbie
Posts: 2

Reg: 02-02-16
01-13-18 06:42 AM - Post#2720929    

Been lurking in the forum for a long time. I have gained so much knowledge. I have a 1960 Bel Air 4 door. 283/PG. I have been doing different upgrades, and currently I am finishing up a Sniper EFI. I am having a hard time finding a wire that has 12v on key on, and key start. Can anyone here assist me with this? My name is Eric by the way!



 
This Forum is Sponsored by
1-800-IMPALAS  *  www.impalas.com
Visit Impala Bob's forum on ChevyTalk
DonSSDD 
Silver Supporting Member
Posts: 6785
DonSSDD
Loc: Nova Scotia, Canada
Reg: 08-21-01
01-13-18 07:02 PM - Post#2720973    
    In response to lowblazer

What are you using for a distributor?

Your + coil wire would have what you are looking for, unless you are using stock points. Then there is a resister wire in the harness.

You should also find a connection on the fusebox powered on by the key, if that is stock.

63 Pontiac Parisienne Sport Coupe(CDN Chev mechanically (409, 4 speed),62 Bel Air SC (sold), 59 El Camino (sold), 62 Bel Air SC(sold), 63 SWC Vette (sold),
Member #2194


 
lowblazer 
Forum Newbie
Posts: 2

Reg: 02-02-16
01-13-18 09:13 PM - Post#2720984    
    In response to DonSSDD

Thanks for the reply. It is still the stock points style distributor. I have checked the fuse panel, and I can find key on 12v, but not a source that is 12v on key on AND key start.



 
DonSSDD 
Silver Supporting Member
Posts: 6785
DonSSDD
Loc: Nova Scotia, Canada
Reg: 08-21-01
01-14-18 05:49 AM - Post#2720991    
    In response to lowblazer

Run one off the ignition switch wire that runs to the coil + side. At the ignition switch it puts out 12V, before it goes into the wire harness where the resistor resides.

63 Pontiac Parisienne Sport Coupe(CDN Chev mechanically (409, 4 speed),62 Bel Air SC (sold), 59 El Camino (sold), 62 Bel Air SC(sold), 63 SWC Vette (sold),
Member #2194


Edited by DonSSDD on 01-14-18 05:50 AM. Reason for edit: No reason given.

 
JayChicago 
"8th Year" Silver Supporting Member
Posts: 323
JayChicago
Loc: Chicago
Reg: 01-03-13
01-17-18 10:56 PM - Post#2721351    
    In response to lowblazer

There is no one place on your car where you can get +12V in both KEY-ON and START modes. The car was designed to keep those two circuits isolated from each other. And if you come off a source in each circuit and then join them together to feed your EFI, each circuit will back-feed the other and cause problems. (like the starter continuing to run in KEY-ON)

I would think you should talk to the EFI supplier; seems like they would have figured out an easy solution. It probably needs to be done using one or two relays. (when a relay springs open, it prevents back-feeding into its circuit)

Another point: To be safe you want your new +12V feeds to be fused. The ignition switch on our cars is ahead of the fuses, so not a good source. The fused source you found at your fuse panel would be good for KEY-ON. And on our old cars the START circuit does not go thru the fuse panel, it is not fused at all! So nothing lost if you tap the START circuit at the ignition switch, but your new feed should then have an in-line fuse within the first few inches.



 
models916 
Valued Contributor
Posts: 4776

Age: 67
Loc: Addison, IL
Reg: 05-28-10
01-19-18 07:21 AM - Post#2721478    
    In response to JayChicago

What about on the starter before the resistance wire? Or remove the resistance wire and use a ballast on the firewall like the 348-409 cars and wire in front of the ballast?



 
Jim Streib 
Senior Member
Posts: 452
Jim Streib
Loc: Saint Louis
Reg: 03-20-03
01-19-18 11:23 AM - Post#2721498    
    In response to lowblazer

While I do not know how accurate this wiring diagram is and if power does drop out when in the crank position on some circuits, here is a complete diagram:



Now below is the above diagram with other circuits removed but traced back off of the coil, through the resistance wire to a plug that also has a wire off of it that goes to the wipers and an over ride relay and then probably inside the car, this circuit splits to things like the output of the ignition switch, power for the oil pressure and temperature light, as well as having a branch for the turn signal flasher.

I would think if you are looking under the dash, see if the power side of the flasher has 12V when the key is in the run AND crank position.



It is possible back on the older years that the output from the ignition switch is only hot when the key is in the run position and dead at all other times and this is why they needed a jumper wire from the starter solenoid to the coil positive to get the motor to fire when it was being cranked over. Testing should show what is going on.

Jim

1968 Chevy II Nova (Garage Find 2013)

https://www.flickr.com/photos/121766713@N04/ albums...

https://www.youtube.com/user/StlNovas/videos

1973 Nova Custom
1974 Nova Spirit Of America


 
models916 
Valued Contributor
Posts: 4776

Age: 67
Loc: Addison, IL
Reg: 05-28-10
01-22-18 05:20 AM - Post#2721722    
    In response to Jim Streib

When cranking you get 12v to the points and the coil for hotter spark. In the run position you get reduced voltage via a resistance wire or a ballast in line to reduce arcing of the points. Both wires are on the starter/solenoid.



 
JayChicago 
"8th Year" Silver Supporting Member
Posts: 323
JayChicago
Loc: Chicago
Reg: 01-03-13
01-22-18 11:02 PM - Post#2721828    
    In response to models916

Yeah. I forgot that the resistor wire doesn't go directly to the coil. The ON circuit's resistor wire goes first to a dead terminal on the starter relay, and from there another wire carries the reduced voltage on up to the coil. Then when the starter relay is engaged that terminal comes alive, feeding a full 12 volts to the coil.

The original poster's problem, finding a point to pick-up +12V in both START and ON modes, is still the same. That terminal on the starter relay would be a good place to pick-up 12V in START, but that terminal is downstream of the resistor, will see reduced voltage (+/-8 volts?) when engine is running.





 
raycow 
Honored Member
Posts: 27440
raycow
Loc: San Francisco, CA
Reg: 11-26-02
01-23-18 01:18 AM - Post#2721833    
    In response to JayChicago

If you don't want to cut into the stock wiring harness you can get 12V off the wiper motor feed, but first check that it is hot with the switch in the start position. I'm not real happy with this hookup though, because it goes through the wiper fuse.

What I did is to use the resistor lead to operate a cube relay. The relay feeds 12V to the coil from the horn relay or any other convenient point under the hood which is hot all the time. No original wiring is disturbed this way and it can easily be restored to stock at any later time if you desire.

Ray

Those who choose an automatic transmission want transportation. Those who choose a manual transmission want to drive.


 
94guy 
Member
Posts: 13

Reg: 08-12-03
03-16-18 05:02 PM - Post#2727868    
    In response to raycow

lowblazer did you ever find a 12v source? i'm doing a 60 impala with the sniper efi also.



 
This Forum is Sponsored by
1-800-IMPALAS  *  www.impalas.com
Visit Impala Bob's forum on ChevyTalk
Icon Legend Permissions Topic Options
Report Post

Quote Post

Quick Reply

Print Topic

Email Topic

738 Views
FusionBB
FusionBB™ Version 2.1
©2003-2006 InteractivePHP, Inc.
Execution time: 0.353 seconds.   Total Queries: 16   Zlib Compression is on.
All times are (GMT -0800) Pacific. Current time is 02:20 PM
Top