Working on the Valve cover, found a mystery wire - The 1947 - Present Chevrolet & GMC Truck Message Board Network

phlegm · 10-04-2005, 10:06 AM

Not sure if this falls under electircal, since its not an issue of the wires not working.

While working on the truck last night I found 3 wires and their termination clip all taped to the AC Compressor Bracket, not connected to anything. The wires run down the top of the engine just inside the Valve ccover in that grove, and are attached to the block with Clips.... any idea what this is supposed to connect to?

Thanks in advance

farside847 · 10-04-2005, 11:49 AM

Does your temp guage work? I seem to remeber the temp sender is on that side of a SB

shaneschevys · 10-04-2005, 12:45 PM

what color are the wires? Some trucks had 2 temp senders on each side of engine one for the guage & one for the temp light in the dash. If your truck is a fact air truck there should be a small solenoid on the side of your carb that idles up your engine when you turn your a/c on. Hope this helps you out.

phlegm · 10-04-2005, 12:56 PM

Both are good suggestions, i will run the both down. I do not ahve a guage cluster, but it could be the dummy light.

I will have to check on the carb solenoid too. would that run directly to the compessor, or somewhere else, I assumed my wires ran to my fuse panel but if it is the ac stuff I could probably trace it back to the the unit somehow.

Anymore suggestions would be welcome!

Longhorn Man · 10-04-2005, 02:58 PM

None of these trucks ever came with 2 sending units. Not originally anyways. The only original location for the temp sending unit for a small block 67 - 72 truck is in the passenger side head between #1 and #3 cylinder exhaust ports.
This may be for the vacume advance delay crap that they had as primitive emissions... Not sure since I have very few details, I think that was mounted on the passenger side of the intake with a relay or something on the firewall.

bucket · 10-04-2005, 05:28 PM

[QUOTE=Longhorn Man]The only original location for the temp sending unit for a small block 67 - 72 truck is in the passenger side head between #1 and #3 cylinder exhaust ports.

Or in the intake manifold near the oil fill tube in the case of a 67 327.

70short/step · 10-04-2005, 05:42 PM

Quote:

Originally Posted by Longhorn Man

None of these trucks ever came with 2 sending units. Not originally anyways. The only original location for the temp sending unit for a small block 67 - 72 truck is in the passenger side head between #1 and #3 cylinder exhaust ports.
This may be for the vacume advance delay crap that they had as primitive emissions... Not sure since I have very few details, I think that was mounted on the passenger side of the intake with a relay or something on the firewall.

Isnt #1 and #3 cylinder exhaust ports located on the drivers side of the engine??

phlegm · 10-04-2005, 05:27 PM

Thanks again guys.

farside847 · 10-04-2005, 06:01 PM

My temp sensor is on the drivers side from the factory. 1971 307 V8

Longhorn Man · 10-04-2005, 07:13 PM

LOL...yes. I ment drivers side..the caddy engine has #1,3,5,&7 on the passenger side. I had it pictured in my head properly...just didn't word it correctly.
As for in the intake... I've never seen that, but my 67/68 hands on portion is minimal.

neonlarry · 10-04-2005, 09:19 PM

Trucks equipped with a TSC system did have two temp sending units. Gauge one in D/S head TSC controll on in the P/S head.

phlegm · 10-05-2005, 02:14 PM

Quote:

Originally Posted by neonlarry

Trucks equipped with a TSC system

What is TSC system? and would it be on my box sticker or sales receipt?

phlegm · 10-05-2005, 08:32 AM

I took a look at the wiring diagrams in my haynes Manual. It was late when I got around to it but I think the temp sensors only have 1 wire going to them that I can tell. The one I found is has 3 wires. It looks a lot like the wiring for my alternator, I thought maybe it was pre rebuild and they replaced it, but it runs down the PS with clips there for it.. alternator is on the other side.

farside847 · 10-05-2005, 11:53 AM

What engine do you have? The stock location of the alternator on a SB is on the driver side too. I have a wire bundle that goes down along the valve cover then splits off to hook up to the alternator and the temp sender. 4 wires I think (correct me if Im wrong)

phlegm · 10-05-2005, 02:11 PM

Sb 350 from a 71, thats why I dont think its for that application. I am surprised that it has 2 sending units for the temprature.... gues I am just going to have to go digging for a termination point to see what it is really for.

I have to go back in anyway, the old gasket didnt set right when I replaced the valve cover, I drove it for a half hr last night and it started oozing once the oil heated up o well, back at it.

neonlarry · 10-05-2005, 03:25 PM

Actually its TCS(my mistype) for transmission controlled spark. It has a switch in the transmission, a relay on the firewall, a temp sensor in P/S head and a solenoid on the intake manifold. It shuts off the vacuum advance in the lower forward gears, the temp sensor overrides this when the engine is cold.

phlegm · 10-05-2005, 03:32 PM

I have a stock 3 spd. this sounds more like something you would put in a Auto Tranny.

neonlarry · 10-05-2005, 04:06 PM

You are correct.

phlegm · 10-05-2005, 04:28 PM

OK back to doing a hunt and peck for the socket.

kbs71 · 10-06-2005, 12:05 AM

Sounds like your truck use to have an under dash A/C unit installed at one time. My 71 has the exact same setup your refering to and it went to the A/C compressor that use to be there when the old under dash unit was installed.

phlegm · 10-06-2005, 08:24 AM

Shouldnt be, I have factory air. but it does look like the same wiring.

patrick66 · 10-06-2005, 04:40 PM

Have you checked the connection for power? If so, does it come on when you turn the ignition on, or is it constant? It's sounding to me like an a/c power source, as said earlier. You may be able to simply cut it off at the source and rid yourself of the problem.

phlegm · 10-07-2005, 08:19 AM

My buddy that rebuilds 350s for his Pontiacs of the same era, said it looks like the TCS harness to him. That it is possible when they did the reubuild the harness included that connection although it was not needed. so they just taped it off incase he ever went automatic. We dont know for sure but that is as good a theory as any.

larry may · 10-07-2005, 06:01 PM

My ole heap has same wires.Do not remember what they went to . Alternator I think , Used to have a six cylinder, Wires were ran a bit different. Than for what is in there for an engine currently. Probably was for an idiot light of sorts and for sure one was for temp gage.

WB72 · 10-11-2005, 04:14 PM

It possibly may be a Engine Block Heater cord...

10-04-2005, 11:49 AM	#2
farside847 Registered User Join Date: Feb 2005 Location: Bay Area, California Posts: 995	Does your temp guage work? I seem to remeber the temp sender is on that side of a SB __________________ 1971 Chevy C10 Shortbed Stepside, 307v8 3-on-the-tree

10-04-2005, 12:56 PM	#4
phlegm Still Green but learning Join Date: Nov 2004 Location: Central NC Posts: 1,895	Both are good suggestions, i will run the both down. I do not ahve a guage cluster, but it could be the dummy light. I will have to check on the carb solenoid too. would that run directly to the compessor, or somewhere else, I assumed my wires ran to my fuse panel but if it is the ac stuff I could probably trace it back to the the unit somehow. Anymore suggestions would be welcome! __________________ -- Cory 71 Cheyenne 10 - SWB, 350, "3 on the tree" AC cab 07 Suburban LTZ 4x4 2010 Acura TL 98 Mastercraft "FrankenStar" 225 27253 UPS/USPS IIOY....nope never was

10-04-2005, 05:27 PM	#8
phlegm Still Green but learning Join Date: Nov 2004 Location: Central NC Posts: 1,895	Thanks again guys. __________________ -- Cory 71 Cheyenne 10 - SWB, 350, "3 on the tree" AC cab 07 Suburban LTZ 4x4 2010 Acura TL 98 Mastercraft "FrankenStar" 225 27253 UPS/USPS IIOY....nope never was

10-04-2005, 06:01 PM	#9
farside847 Registered User Join Date: Feb 2005 Location: Bay Area, California Posts: 995	My temp sensor is on the drivers side from the factory. 1971 307 V8 __________________ 1971 Chevy C10 Shortbed Stepside, 307v8 3-on-the-tree

10-04-2005, 09:19 PM	#11
neonlarry Registered User Join Date: Feb 2002 Location: Vacaville, CA Posts: 2,746	Trucks equipped with a TSC system did have two temp sending units. Gauge one in D/S head TSC controll on in the P/S head. __________________ 70 C/10 Light Red 350/TH350, HEI, Duals w/40 series Flows, 91 seat, LED taillights 99 Pontiac S/C GTP, SLP Ram Air hood, GMPP Konis & springs 95 Neon ACR, MP PCM, AFX UDP, 3.0 CAI

10-04-2005, 10:06 AM	#1
phlegm Still Green but learning Join Date: Nov 2004 Location: Central NC Posts: 1,895	Working on the Valve cover, found a mystery wire Not sure if this falls under electircal, since its not an issue of the wires not working. While working on the truck last night I found 3 wires and their termination clip all taped to the AC Compressor Bracket, not connected to anything. The wires run down the top of the engine just inside the Valve ccover in that grove, and are attached to the block with Clips.... any idea what this is supposed to connect to? Thanks in advance __________________ -- Cory 71 Cheyenne 10 - SWB, 350, "3 on the tree" AC cab 07 Suburban LTZ 4x4 2010 Acura TL 98 Mastercraft "FrankenStar" 225 27253 UPS/USPS IIOY....nope never was

10-04-2005, 12:45 PM	#3
shaneschevys Its always something! Join Date: Aug 2005 Location: FT Worth,TX Posts: 4,992	what color are the wires? Some trucks had 2 temp senders on each side of engine one for the guage & one for the temp light in the dash. If your truck is a fact air truck there should be a small solenoid on the side of your carb that idles up your engine when you turn your a/c on. Hope this helps you out. __________________ 79 p10 stepvan 72 Short Fleetside 72 Suburban 67 GMC One Ton Flatbed 64 Short Fleetside 57 Chevy 2DR Hard Top 57 Chevy 2dr wagon 65 f* short fleet 63 C 60 Flatbed Member of the patina club**

10-04-2005, 02:58 PM	#5
Longhorn Man its all about the +6 inches Join Date: Jan 2001 Location: Hilliard Ohio Posts: 2,693	None of these trucks ever came with 2 sending units. Not originally anyways. The only original location for the temp sending unit for a small block 67 - 72 truck is in the passenger side head between #1 and #3 cylinder exhaust ports. This may be for the vacume advance delay crap that they had as primitive emissions... Not sure since I have very few details, I think that was mounted on the passenger side of the intake with a relay or something on the firewall.

10-04-2005, 05:28 PM	#6
bucket Registered User Join Date: Aug 2001 Location: Shawnee, KS Posts: 923	[QUOTE=Longhorn Man]The only original location for the temp sending unit for a small block 67 - 72 truck is in the passenger side head between #1 and #3 cylinder exhaust ports. Or in the intake manifold near the oil fill tube in the case of a 67 327.

10-04-2005, 07:13 PM	#10
Longhorn Man its all about the +6 inches Join Date: Jan 2001 Location: Hilliard Ohio Posts: 2,693	LOL...yes. I ment drivers side..the caddy engine has #1,3,5,&7 on the passenger side. I had it pictured in my head properly...just didn't word it correctly. As for in the intake... I've never seen that, but my 67/68 hands on portion is minimal.

10-05-2005, 08:32 AM	#13
phlegm Still Green but learning Join Date: Nov 2004 Location: Central NC Posts: 1,895	I took a look at the wiring diagrams in my haynes Manual. It was late when I got around to it but I think the temp sensors only have 1 wire going to them that I can tell. The one I found is has 3 wires. It looks a lot like the wiring for my alternator, I thought maybe it was pre rebuild and they replaced it, but it runs down the PS with clips there for it.. alternator is on the other side. __________________ -- Cory 71 Cheyenne 10 - SWB, 350, "3 on the tree" AC cab 07 Suburban LTZ 4x4 2010 Acura TL 98 Mastercraft "FrankenStar" 225 27253 UPS/USPS IIOY....nope never was

10-05-2005, 11:53 AM	#14
farside847 Registered User Join Date: Feb 2005 Location: Bay Area, California Posts: 995	What engine do you have? The stock location of the alternator on a SB is on the driver side too. I have a wire bundle that goes down along the valve cover then splits off to hook up to the alternator and the temp sender. 4 wires I think (correct me if Im wrong) __________________ 1971 Chevy C10 Shortbed Stepside, 307v8 3-on-the-tree Last edited by farside847; 10-05-2005 at 11:53 AM.

10-05-2005, 02:11 PM	#15
phlegm Still Green but learning Join Date: Nov 2004 Location: Central NC Posts: 1,895	Sb 350 from a 71, thats why I dont think its for that application. I am surprised that it has 2 sending units for the temprature.... gues I am just going to have to go digging for a termination point to see what it is really for. I have to go back in anyway, the old gasket didnt set right when I replaced the valve cover, I drove it for a half hr last night and it started oozing once the oil heated up o well, back at it. __________________ -- Cory 71 Cheyenne 10 - SWB, 350, "3 on the tree" AC cab 07 Suburban LTZ 4x4 2010 Acura TL 98 Mastercraft "FrankenStar" 225 27253 UPS/USPS IIOY....nope never was

10-05-2005, 03:25 PM	#16
neonlarry Registered User Join Date: Feb 2002 Location: Vacaville, CA Posts: 2,746	Actually its TCS(my mistype) for transmission controlled spark. It has a switch in the transmission, a relay on the firewall, a temp sensor in P/S head and a solenoid on the intake manifold. It shuts off the vacuum advance in the lower forward gears, the temp sensor overrides this when the engine is cold. __________________ 70 C/10 Light Red 350/TH350, HEI, Duals w/40 series Flows, 91 seat, LED taillights 99 Pontiac S/C GTP, SLP Ram Air hood, GMPP Konis & springs 95 Neon ACR, MP PCM, AFX UDP, 3.0 CAI

10-05-2005, 03:32 PM	#17
phlegm Still Green but learning Join Date: Nov 2004 Location: Central NC Posts: 1,895	I have a stock 3 spd. this sounds more like something you would put in a Auto Tranny. __________________ -- Cory 71 Cheyenne 10 - SWB, 350, "3 on the tree" AC cab 07 Suburban LTZ 4x4 2010 Acura TL 98 Mastercraft "FrankenStar" 225 27253 UPS/USPS IIOY....nope never was



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10-05-2005, 04:06 PM	#18
neonlarry Registered User Join Date: Feb 2002 Location: Vacaville, CA Posts: 2,746	You are correct. __________________ 70 C/10 Light Red 350/TH350, HEI, Duals w/40 series Flows, 91 seat, LED taillights 99 Pontiac S/C GTP, SLP Ram Air hood, GMPP Konis & springs 95 Neon ACR, MP PCM, AFX UDP, 3.0 CAI

10-05-2005, 04:28 PM	#19
phlegm Still Green but learning Join Date: Nov 2004 Location: Central NC Posts: 1,895	OK back to doing a hunt and peck for the socket. __________________ -- Cory 71 Cheyenne 10 - SWB, 350, "3 on the tree" AC cab 07 Suburban LTZ 4x4 2010 Acura TL 98 Mastercraft "FrankenStar" 225 27253 UPS/USPS IIOY....nope never was

10-06-2005, 12:05 AM	#20
kbs71 71 rustless in texas Join Date: Aug 2004 Location: Houston, TX Posts: 257	Sounds like your truck use to have an under dash A/C unit installed at one time. My 71 has the exact same setup your refering to and it went to the A/C compressor that use to be there when the old under dash unit was installed. __________________ "The secret to creativity is knowing how to hide your sources." "No one really listens to anyone else, and if you try it for a while you'll see why" 71 C-10 LWB presently in a perpetual state of disassembly '96 Toyota (my work car) '04 Mustang Convertable (wife's car & other money pit) Latest aquesition and why my trucks still in the garage covered with junk.. 2010 Aqua Blue metallic 6 speed Manual LS3 2SS/RS Camaro (I want one of these in my truck FAQ here VENDORS here SUPPORT THE BOARD here My second favorite SITE

10-06-2005, 08:24 AM	#21
phlegm Still Green but learning Join Date: Nov 2004 Location: Central NC Posts: 1,895	Shouldnt be, I have factory air. but it does look like the same wiring. __________________ -- Cory 71 Cheyenne 10 - SWB, 350, "3 on the tree" AC cab 07 Suburban LTZ 4x4 2010 Acura TL 98 Mastercraft "FrankenStar" 225 27253 UPS/USPS IIOY....nope never was

10-06-2005, 04:40 PM	#22
patrick66 crazy about dem trucks! Join Date: Jan 2005 Location: Oklahoma City Posts: 75	Have you checked the connection for power? If so, does it come on when you turn the ignition on, or is it constant? It's sounding to me like an a/c power source, as said earlier. You may be able to simply cut it off at the source and rid yourself of the problem. __________________ patrick66 - '67 C-10

10-07-2005, 08:19 AM	#23
phlegm Still Green but learning Join Date: Nov 2004 Location: Central NC Posts: 1,895	My buddy that rebuilds 350s for his Pontiacs of the same era, said it looks like the TCS harness to him. That it is possible when they did the reubuild the harness included that connection although it was not needed. so they just taped it off incase he ever went automatic. We dont know for sure but that is as good a theory as any. __________________ -- Cory 71 Cheyenne 10 - SWB, 350, "3 on the tree" AC cab 07 Suburban LTZ 4x4 2010 Acura TL 98 Mastercraft "FrankenStar" 225 27253 UPS/USPS IIOY....nope never was

10-07-2005, 06:01 PM	#24
larry may Senior Member Join Date: Jul 2005 Location: MISSOURI Posts: 3,256	My ole heap has same wires.Do not remember what they went to . Alternator I think , Used to have a six cylinder, Wires were ran a bit different. Than for what is in there for an engine currently. Probably was for an idiot light of sorts and for sure one was for temp gage.

10-11-2005, 04:14 PM	#25
WB72 Before and After Join Date: Feb 2000 Location: Leduc, Alberta CANADA Posts: 632	It possibly may be a Engine Block Heater cord... __________________ Not Grandpa's C-20 anymore... 383 Stroker 425HP, 485Ft/Lbs Lowered 3.5" Front / 5" Rear 66,000 miles. Alberta, CANADA

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