Anybody know what this switch is? - The 1947 - Present Chevrolet & GMC Truck Message Board Network

70c10 · 12-12-2004, 06:04 PM

In the wiring schematics for our V8 trucks I see a label for "TRANS CONT SPARK TEMP SW" in front of the passenger side head. It is labeled Dark Green wire which I found unhooked. What does that switch do and where is it located?

cableguy0 · 12-12-2004, 06:21 PM

im pretty sure that is old emissions crap that wouldnt have any effect on your hei and new carb anyways

*bisquik65* · 12-12-2004, 06:44 PM

That switch retards the timing upon engine and transmission temp. It holds the timing back until the switch opens. You are better off without it. My 70 sb had it and my 70 2wd blazer also. Not any more

cableguy0 · 12-12-2004, 06:46 PM

i dont remember if it is or not but i imagine your hei is wired how it should be to a 12 volt hot key on if so its bypassed anyways even if the switch was hooked up

70c10 · 12-12-2004, 06:56 PM

Thanks guys. I found this wire on my dads truck today. I was looking for the dark green wire to hook up his temp gauge and came across this one. I find something new everyday with these trucks!

jimfulco · 12-13-2004, 02:47 AM

TCS is transmission controlled spark. It eliminates the vacuum advance in all gears except high. That switch eliminates the TCS when the motor is cold.

70c10 · 12-13-2004, 08:24 AM

Just curious- where is the switch actually located?

mrein3 · 12-13-2004, 08:50 AM

I just installed a new 383 in my truck. I put a new Edelbrock 1406 on it. I used that wire for the +12 volts to my new carb.

7T1BURB · 12-13-2004, 09:37 AM

TCS is actually located on the transmission....has a male lead on the switch itself (to attach the green wire) and other end of switch is threaded into the transmission. On the end of the switch threaded into the transmission, is a ball/plunger setup that is activated by internal transmission workings..

Hope this helps..

12-12-2004, 06:04 PM	#1
70c10 67-72 Addict! Join Date: Feb 2002 Location: The TAX State! Posts: 7,856	Anybody know what this switch is? In the wiring schematics for our V8 trucks I see a label for "TRANS CONT SPARK TEMP SW" in front of the passenger side head. It is labeled Dark Green wire which I found unhooked. What does that switch do and where is it located? __________________ Jim 1970 C/10 Fleetside w/Ghost Flames Lowered 4.5" front and 4" rear (Raked) 355/350 Turbo w/shift kit 10" Redneck Performance Verter w/2500 stall Hooker Super Comps part#2808-1 Performer RPM Air-Gap 12 Bolt w/3:73 gears- Eaton Posi Comp Cams XE262 with 1.6 Crane Energizers, Road Demon 625 and Brodix IK 180 heads

12-12-2004, 06:21 PM	#2
cableguy0 Senior Member Join Date: Apr 2000 Location: Delta,Pa Posts: 14,948	im pretty sure that is old emissions crap that wouldnt have any effect on your hei and new carb anyways __________________ Owner of North Point Car Care in Dundalk Md. We specialize in custom exhaust on both modern and classic vehicles. We are a full service auto shop from classics to modern vehicles. Feel free to contact me with questions. I will give a 10% discount to any board member.

12-12-2004, 06:46 PM	#4
cableguy0 Senior Member Join Date: Apr 2000 Location: Delta,Pa Posts: 14,948	i dont remember if it is or not but i imagine your hei is wired how it should be to a 12 volt hot key on if so its bypassed anyways even if the switch was hooked up __________________ Owner of North Point Car Care in Dundalk Md. We specialize in custom exhaust on both modern and classic vehicles. We are a full service auto shop from classics to modern vehicles. Feel free to contact me with questions. I will give a 10% discount to any board member.

12-12-2004, 06:56 PM	#5
70c10 67-72 Addict! Join Date: Feb 2002 Location: The TAX State! Posts: 7,856	Thanks guys. I found this wire on my dads truck today. I was looking for the dark green wire to hook up his temp gauge and came across this one. I find something new everyday with these trucks! __________________ Jim 1970 C/10 Fleetside w/Ghost Flames Lowered 4.5" front and 4" rear (Raked) 355/350 Turbo w/shift kit 10" Redneck Performance Verter w/2500 stall Hooker Super Comps part#2808-1 Performer RPM Air-Gap 12 Bolt w/3:73 gears- Eaton Posi Comp Cams XE262 with 1.6 Crane Energizers, Road Demon 625 and Brodix IK 180 heads

12-13-2004, 08:24 AM	#7
70c10 67-72 Addict! Join Date: Feb 2002 Location: The TAX State! Posts: 7,856	Just curious- where is the switch actually located? __________________ Jim 1970 C/10 Fleetside w/Ghost Flames Lowered 4.5" front and 4" rear (Raked) 355/350 Turbo w/shift kit 10" Redneck Performance Verter w/2500 stall Hooker Super Comps part#2808-1 Performer RPM Air-Gap 12 Bolt w/3:73 gears- Eaton Posi Comp Cams XE262 with 1.6 Crane Energizers, Road Demon 625 and Brodix IK 180 heads

12-12-2004, 06:44 PM	#3
bisquik65 Account Suspended Join Date: Apr 2004 Location: N.C. high country Posts: 6,107	That switch retards the timing upon engine and transmission temp. It holds the timing back until the switch opens. You are better off without it. My 70 sb had it and my 70 2wd blazer also. Not any more

12-13-2004, 02:47 AM	#6
jimfulco Registered User Join Date: May 2003 Location: Shreveport LA Posts: 3,170	TCS is transmission controlled spark. It eliminates the vacuum advance in all gears except high. That switch eliminates the TCS when the motor is cold.

12-13-2004, 08:50 AM	#8
mrein3 Registered User Join Date: Feb 2000 Location: Center City, MN, USA Posts: 3,254	I just installed a new 383 in my truck. I put a new Edelbrock 1406 on it. I used that wire for the +12 volts to my new carb. __________________ '70 cab, '71 chassis, 383, TH350, NP205. '71 Malibu convertible '72 Malibu hard top Center City, MN

12-13-2004, 09:37 AM	#9
7T1BURB Registered User Join Date: Aug 2002 Location: Newport News, VA Posts: 190	Tcs TCS is actually located on the transmission....has a male lead on the switch itself (to attach the green wire) and other end of switch is threaded into the transmission. On the end of the switch threaded into the transmission, is a ball/plunger setup that is activated by internal transmission workings.. Hope this helps..



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