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

angelsairman · 03-10-2004, 01:27 AM

ok guys..here i am with another one of my questions, i have these two connectors on the drivers side of the firewall(top right in picture). They both mostly run into one harness and all but one wire has been cut. I dont know if it matters but it had been converted to Int Reg Alt. Can anyone tell me what these are and what the control so i can fix this mess??? I tried to find them on the wiring diagram but got to lost. Any help would be appreciated....

angelsairman · 03-10-2004, 01:36 AM

i guess i should have mentioned that this is a 71 C10 half ton 2wd with a v8........

stelth2002 · 03-10-2004, 01:42 AM

never seen them before on any other truck ive had What it goto?

angelsairman · 03-10-2004, 01:44 AM

i wish it knew what it went to all the wires have been cut but one green one with a spade connector on the end.

72 CustomCamper · 03-10-2004, 01:57 AM

Those are for the trans spark control BS. My 71 blazer had them and so did 72Blazerman's I didn't have to worry with them on my truck as I used it for parts, but on Doug's truck whin I rebuilt his wiring harness I deleated them...

Chuck

angelsairman · 03-10-2004, 02:05 AM

so basically i shouldnt worry about them just cap off the cut ends?? What funtion did the trans aprak control serve, ive already dropped in a 350 and swapped the 3 on the tree for a automatic.. So i shouldnt need them..correct?? But just for gee whiz information just wondering what they did do.

72 CustomCamper · 03-10-2004, 02:16 AM

You should be able to follow the wires up into the plastic wiring gutter on the fire wall and there should be a dark brown wire with a single blade plug where it connects to the rest of the harness.. I don't remember the whole thinking by GM on it but basicly I think it would keep the vaccume advance retarded until the trans was in high gear...

Chuck

jimfulco · 03-10-2004, 02:56 AM

It's a smog device that cuts the vacuum advance out except in high gear. TCS=transmission-controlled-spark

J.Lance · 03-10-2004, 10:11 AM

Basically what the other guys said. The wiring goes to another temp. sending unit on the passenger side of the block and to a vacuum solenoid placed inline between the vacuum advance canister and the carb. Also runs to a idle control switch on the carb. The entire harness is self sustained and can be removed without effecting your main harness. Just remove the relays from the firewall and pull the harness out of the gutter.

Basically it prevented any vacuum advance until the motor heated up to proper operating temperature. Early emissions technology. Unless you want to keep everything stock, tearing it out is the norm.

bpmcgee · 03-10-2004, 10:19 AM

They are quite correct. Further, if any of the parts (especially the vacuum switch) is missing, they are impossible to replace today.

If you still have the parts, you may want to label and hold onto them -- someone who wants to return to completely original is sure to ask for them someday.

Brian

03-10-2004, 01:27 AM	#1
angelsairman Future Owner Join Date: Jul 2003 Location: Grand Forks AFB, ND Posts: 151	What are these connections for?? ok guys..here i am with another one of my questions, i have these two connectors on the drivers side of the firewall(top right in picture). They both mostly run into one harness and all but one wire has been cut. I dont know if it matters but it had been converted to Int Reg Alt. Can anyone tell me what these are and what the control so i can fix this mess??? I tried to find them on the wiring diagram but got to lost. Any help would be appreciated.... Attached Images __________________ Its not the end result that counts most...its the journey along the way that's most rewarding My truck doesn't leak, it just marks it's territory

03-10-2004, 01:36 AM	#2
angelsairman Future Owner Join Date: Jul 2003 Location: Grand Forks AFB, ND Posts: 151	i guess i should have mentioned that this is a 71 C10 half ton 2wd with a v8........ __________________ Its not the end result that counts most...its the journey along the way that's most rewarding My truck doesn't leak, it just marks it's territory

03-10-2004, 01:42 AM	#3
stelth2002 Young Gun wth Fast Inline Join Date: Jan 2002 Location: Idaho Posts: 1,475	never seen them before on any other truck ive had What it goto? __________________ 1967 Chevrolet LWB with built 292! 415 ft. lbs of torque, 4 speed :O with 27% overdrive too, 3.73 Posi. Frame and body done... getting painted!!!

03-10-2004, 01:44 AM	#4
angelsairman Future Owner Join Date: Jul 2003 Location: Grand Forks AFB, ND Posts: 151	i wish it knew what it went to all the wires have been cut but one green one with a spade connector on the end. __________________ Its not the end result that counts most...its the journey along the way that's most rewarding My truck doesn't leak, it just marks it's territory

03-10-2004, 01:57 AM	#5
72 CustomCamper huh ??? Join Date: Nov 2002 Location: Fredericksburg,Va. Posts: 3,369	Those are for the trans spark control BS. My 71 blazer had them and so did 72Blazerman's I didn't have to worry with them on my truck as I used it for parts, but on Doug's truck whin I rebuilt his wiring harness I deleated them... Chuck __________________ 90 Blazer Silverado 350w/ 700R4 and 32" Kelly's "I am a bomb technician. If you see me running try to keep up!"

03-10-2004, 02:05 AM	#6
angelsairman Future Owner Join Date: Jul 2003 Location: Grand Forks AFB, ND Posts: 151	so basically i shouldnt worry about them just cap off the cut ends?? What funtion did the trans aprak control serve, ive already dropped in a 350 and swapped the 3 on the tree for a automatic.. So i shouldnt need them..correct?? But just for gee whiz information just wondering what they did do. __________________ Its not the end result that counts most...its the journey along the way that's most rewarding My truck doesn't leak, it just marks it's territory

03-10-2004, 02:16 AM	#7
72 CustomCamper huh ??? Join Date: Nov 2002 Location: Fredericksburg,Va. Posts: 3,369	You should be able to follow the wires up into the plastic wiring gutter on the fire wall and there should be a dark brown wire with a single blade plug where it connects to the rest of the harness.. I don't remember the whole thinking by GM on it but basicly I think it would keep the vaccume advance retarded until the trans was in high gear... Chuck __________________ 90 Blazer Silverado 350w/ 700R4 and 32" Kelly's "I am a bomb technician. If you see me running try to keep up!"

03-10-2004, 02:56 AM	#8
jimfulco Registered User Join Date: May 2003 Location: Shreveport LA Posts: 3,170	It's a smog device that cuts the vacuum advance out except in high gear. TCS=transmission-controlled-spark

03-10-2004, 10:11 AM	#9
J.Lance Too many is never enough! Join Date: May 2003 Location: Idaho Falls, ID Posts: 455	relays Basically what the other guys said. The wiring goes to another temp. sending unit on the passenger side of the block and to a vacuum solenoid placed inline between the vacuum advance canister and the carb. Also runs to a idle control switch on the carb. The entire harness is self sustained and can be removed without effecting your main harness. Just remove the relays from the firewall and pull the harness out of the gutter. Basically it prevented any vacuum advance until the motor heated up to proper operating temperature. Early emissions technology. Unless you want to keep everything stock, tearing it out is the norm. __________________ Jason 1968 K10 SWB Fleetside 1971 K2500 GMC LWB 1968 K20 (later frame, donor body) 1972 C20 LWB parts truck 1993 K2500 Suburban, tow rig, 454, 4L80E NEW!! 18' Siem's car hauler 2004 Honda Odyssey (family man!)

03-10-2004, 10:19 AM	#10
bpmcgee Registered User Join Date: Mar 2003 Location: Northern Illinois Posts: 2,181	They are quite correct. Further, if any of the parts (especially the vacuum switch) is missing, they are impossible to replace today. If you still have the parts, you may want to label and hold onto them -- someone who wants to return to completely original is sure to ask for them someday. Brian



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