HELP. 1Wire to solenoid , what color - The 1947 - Present Chevrolet & GMC Truck Message Board Network

**1970 CST Short Wide** · 02-26-2022, 01:58 PM

My Sons Truck only has 1 terminal at the solenoid plus the bat cable. What color wire goes to the solenoid Yellow or Purple???

The only thing I know about electricity is , You can’t see it and It Will Kill You, so I Don’t play with it

**Steeveedee** · 02-26-2022, 02:15 PM

Purple wire goes to the "S" terminal. The yellow wire provides ignition power during cranking. If he has electronic ignition, the yellow wire is vestigial.

**1970 CST Short Wide** · 02-26-2022, 02:52 PM

vestigial ???? Yes he has HEI

**LockDoc** · 02-26-2022, 03:22 PM

-

Quote:

Originally Posted by 1970 CST Short Wide

vestigial ???? Yes he has HEI

That's what I said too...??.. I'm too lazy to look it up..

The yellow wire is not needed if he has the HEI. Purple wire goes to the small terminal. ("S" for solenoid)

LockDoc

RichardJ · 02-26-2022, 06:35 PM

It isn't an issue of not being used with an HEI ignition. It is more of a matter that it should not be used with an HEI.

The "R" terminal (sometimes labeled as "I" terminal) connects to a little bent copper finger inside the solenoid cap. The finger should contact the solenoid Disc, only when the solenoid is energized.

The solenoid contains two coils. A Hold-in winding and a Pull-in winding and both generate a large magnetic field when energized. When the 12v is removed from the "S" terminal, the magnetic field collapses and a very high EMF, voltage spike is generated across the coils.

If the solenoid disc flops the wrong way and/or the copper finger is bent incorrectly, that High voltage spike can travel up that yellow wire and fry the HEI module.

With the old points ignition, a high voltage spike from the solenoid, applied to the ignition coil would go completely unnoticed. It's busy generating its own voltage spike.

**1970 CST Short Wide** · 02-26-2022, 11:48 PM

It was the Purple wire. The reason we didn’t have power to it was that it runs through the neutral safety switch. We had changed the column to standard from Auto (going with 4 speed) so the NSS needed to be jumped. Problem solved

**dmjlambert** · 02-27-2022, 06:06 PM

So now the neutral safety switch is vestigial!

**1970 CST Short Wide** · 02-27-2022, 08:08 PM

Quote:

Originally Posted by dmjlambert

So now the neutral safety switch is vestigial!

Yep - What he said

**Ol Blue K20** · 02-28-2022, 09:32 AM

I look it up, weird word but it fits ....

02-26-2022, 01:58 PM	#1
1970 CST Short Wide Senior Moment Join Date: Mar 2002 Location: Pittsburg Ca Posts: 4,111	HELP. 1Wire to solenoid , what color My Sons Truck only has 1 terminal at the solenoid plus the bat cable. What color wire goes to the solenoid Yellow or Purple??? The only thing I know about electricity is , You can’t see it and It Will Kill You, so I Don’t play with it __________________ 1970 CST LS 1 6 speed Ford 9 inch Detroit Tru Track, Dakota Didgital, Vintage Air, QA1 Coil Overs Front & Rear Lots of FUN 2013 GMC PU, Oldest Son 71 GMC LWB. QA1 Suspension, Angry SB. Youngest Son 2019 GMC Diesil Dually. Youngest Son 2017 Toyota SUV Daughters car 2018 Traverse , Wife’s Ride Pittsburg Ca 94565

02-26-2022, 02:15 PM	#2
Steeveedee Who Changed This? Join Date: Jan 2013 Location: Simi Valley, CA Posts: 10,342	Re: HELP. 1Wire to solenoid , what color Purple wire goes to the "S" terminal. The yellow wire provides ignition power during cranking. If he has electronic ignition, the yellow wire is vestigial. __________________ ~Steven '70 Chevy 3/4T Longhorn CST 402/400/3.56 Custom Camper Simi Valley, CA

02-26-2022, 02:52 PM	#3
1970 CST Short Wide Senior Moment Join Date: Mar 2002 Location: Pittsburg Ca Posts: 4,111	Re: HELP. 1Wire to solenoid , what color vestigial ???? Yes he has HEI __________________ 1970 CST LS 1 6 speed Ford 9 inch Detroit Tru Track, Dakota Didgital, Vintage Air, QA1 Coil Overs Front & Rear Lots of FUN 2013 GMC PU, Oldest Son 71 GMC LWB. QA1 Suspension, Angry SB. Youngest Son 2019 GMC Diesil Dually. Youngest Son 2017 Toyota SUV Daughters car 2018 Traverse , Wife’s Ride Pittsburg Ca 94565

02-26-2022, 06:35 PM	#5
RichardJ Registered User Join Date: Apr 2010 Location: So Cal Posts: 1,427	Re: HELP. 1Wire to solenoid , what color It isn't an issue of not being used with an HEI ignition. It is more of a matter that it should not be used with an HEI. The "R" terminal (sometimes labeled as "I" terminal) connects to a little bent copper finger inside the solenoid cap. The finger should contact the solenoid Disc, only when the solenoid is energized. The solenoid contains two coils. A Hold-in winding and a Pull-in winding and both generate a large magnetic field when energized. When the 12v is removed from the "S" terminal, the magnetic field collapses and a very high EMF, voltage spike is generated across the coils. If the solenoid disc flops the wrong way and/or the copper finger is bent incorrectly, that High voltage spike can travel up that yellow wire and fry the HEI module. With the old points ignition, a high voltage spike from the solenoid, applied to the ignition coil would go completely unnoticed. It's busy generating its own voltage spike. Attached Images __________________ '67 GMC 2500, 292, 4spd, AC

02-26-2022, 11:48 PM	#6
1970 CST Short Wide Senior Moment Join Date: Mar 2002 Location: Pittsburg Ca Posts: 4,111	Re: HELP. 1Wire to solenoid , what color It was the Purple wire. The reason we didn’t have power to it was that it runs through the neutral safety switch. We had changed the column to standard from Auto (going with 4 speed) so the NSS needed to be jumped. Problem solved __________________ 1970 CST LS 1 6 speed Ford 9 inch Detroit Tru Track, Dakota Didgital, Vintage Air, QA1 Coil Overs Front & Rear Lots of FUN 2013 GMC PU, Oldest Son 71 GMC LWB. QA1 Suspension, Angry SB. Youngest Son 2019 GMC Diesil Dually. Youngest Son 2017 Toyota SUV Daughters car 2018 Traverse , Wife’s Ride Pittsburg Ca 94565

02-27-2022, 06:06 PM	#7
dmjlambert Senior Member Join Date: Apr 2016 Location: Cypress, TX Posts: 3,656	Re: HELP. 1Wire to solenoid , what color So now the neutral safety switch is vestigial!

02-28-2022, 09:32 AM	#9
Ol Blue K20 Proprietor of Dale's Corner Join Date: Nov 2012 Location: Vacaville , CA Posts: 16,023	Re: HELP. 1Wire to solenoid , what color I look it up, weird word but it fits .... __________________ "Some Days Chickens And Some Days Feathers" Dale XNGH ECV Sam Brannan 1004 R.I.P. 67ChevyRedneck R.I.P. Grumpy Old Man



Register or Log In To remove these advertisements.

Register or Log In To remove these advertisements.