What are these for? - The 1947 - Present Chevrolet & GMC Truck Message Board Network

speed · 02-11-2006, 01:16 PM

I'm trying to get some of the wiring sorted out in my 83, have no idea what they are for. Both are on the passenger side by the rear of the valve cover.
Caution LARGE pictures!
http://photobucket.com/albums/c282/i...hevy%20truck/?
Also does anybody have a good wiring diagram for an 83 underhood and dash especially they could email to me?
TIA

82c10 · 02-11-2006, 01:42 PM

Quote:

Originally Posted by speed

I'm trying to get some of the wiring sorted out in my 83, have no idea what they are for. Both are on the passenger side by the rear of the valve cover.
Caution LARGE pictures!
http://photobucket.com/albums/c282/i...hevy%20truck/?
Also does anybody have a good wiring diagram for an 83 underhood and dash especially they could email to me?
TIA

they are for a lockup transmsiion, best i can remember, i am betting that the trans in it is not original, and has been replaced with a better one

speed · 02-11-2006, 02:23 PM

The tranny has been swapped out a couple of owners ago, originally a 700r4. Is the part up near the cowl a vacumme switch? There is a piece of hose still on it.

Prerunner1982 · 02-11-2006, 03:47 PM

yes it is vac operated, my 82 with th350c has it as well, i am referring to the pic on the right in the link you provided.

**swervin ervin** · 02-11-2006, 04:38 PM

IM002498.jpg

This is the ESC vacuum switch. Here is what it does.

ESC Vacuum Switch
On LE9 engine equipped vehicles with automatic transmission a "tip in" vacuum switch is used. Its function is to provide a momentary contact closure (signal) to the ESC controller during a throttle "tip in" condition which then briefly retards spark timing to minimize knock. The switch contacts are normally open under steady engine vacuum conditions including no vacuum, and all brief increasing vacuum conditions. Basically the switch closes only during rapidly decreasing vacuum conditions such as that encountered on rapid throttle operation.

IM002499.jpg

This is once again, part of the ESC system. Read this article I wrote about it.
http://www.73-87.com/7387garage/drivetrain/escrepl.htm

speed · 02-11-2006, 06:07 PM

Thanks that explains alot. Since it has had the dist swapped out, I'm going to get rid of the ESC parts & HEI in there and go with a GMPP HEI, Eldelbrock intake and carb.
The wiring under the dash has been hacked up bad so if I can find a good harness to start with, I'll swap that out too.

02-11-2006, 01:16 PM	#1
speed Junior Member Join Date: Jan 2006 Location: Northern Iowa Posts: 258	What are these for? I'm trying to get some of the wiring sorted out in my 83, have no idea what they are for. Both are on the passenger side by the rear of the valve cover. Caution LARGE pictures! http://photobucket.com/albums/c282/i...hevy%20truck/? Also does anybody have a good wiring diagram for an 83 underhood and dash especially they could email to me? TIA __________________ Jeff J ---------- 86 El Camino 81 Monte Carlo 81 Regal 04 Colorado Last edited by speed; 02-11-2006 at 01:18 PM.

02-11-2006, 02:23 PM	#3
speed Junior Member Join Date: Jan 2006 Location: Northern Iowa Posts: 258	Re: What are these for? The tranny has been swapped out a couple of owners ago, originally a 700r4. Is the part up near the cowl a vacumme switch? There is a piece of hose still on it. __________________ Jeff J ---------- 86 El Camino 81 Monte Carlo 81 Regal 04 Colorado

02-11-2006, 03:47 PM	#4
Prerunner1982 Registered User Join Date: Oct 2002 Location: Edmond, OK Posts: 5,904	Re: What are these for? yes it is vac operated, my 82 with th350c has it as well, i am referring to the pic on the right in the link you provided. __________________ Jon 1982 Chevy Silverado 350/th350.... RETIRED 1993 Jeep XJ 2 door(Cherokee) 4wd 4.0ltr/AX-15 (5spd)/NP231 .... Oklahoma Roll Call

02-11-2006, 04:38 PM	#5
swervin ervin You get what you pay for Join Date: Dec 1999 Location: Cherryville, NC Posts: 4,798	Re: What are these for? IM002498.jpg This is the ESC vacuum switch. Here is what it does. ESC Vacuum Switch On LE9 engine equipped vehicles with automatic transmission a "tip in" vacuum switch is used. Its function is to provide a momentary contact closure (signal) to the ESC controller during a throttle "tip in" condition which then briefly retards spark timing to minimize knock. The switch contacts are normally open under steady engine vacuum conditions including no vacuum, and all brief increasing vacuum conditions. Basically the switch closes only during rapidly decreasing vacuum conditions such as that encountered on rapid throttle operation. IM002499.jpg This is once again, part of the ESC system. Read this article I wrote about it. http://www.73-87.com/7387garage/drivetrain/escrepl.htm __________________ Mike 1985 Chevy C-10

02-11-2006, 06:07 PM	#6
speed Junior Member Join Date: Jan 2006 Location: Northern Iowa Posts: 258	Re: What are these for? Thanks that explains alot. Since it has had the dist swapped out, I'm going to get rid of the ESC parts & HEI in there and go with a GMPP HEI, Eldelbrock intake and carb. The wiring under the dash has been hacked up bad so if I can find a good harness to start with, I'll swap that out too. __________________ Jeff J ---------- 86 El Camino 81 Monte Carlo 81 Regal 04 Colorado

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