dave m Posted June 20, 2017 Share Posted June 20, 2017 Hi I am in the process of replacing the wire loom/channel that is on the firewall center just above the distributor it had a relay ? mounted to it. when I tried to unplug it just broke in pieces. I thought it was a horn relay ????? but looking on opgi site it looks like this??????? 1970-75 Monte Carlo Transmission Controlled Spark Relay Email Plus Pin It Tweet Share 1970-75 Monte Carlo Transmission Controlled Spark Relay Part# CH28222 Be the First to Review SAVE: $9.96 Retail: $102.95 OPGI Price: $92.99 Part Type: ® = Authentic reproduction of the original GM productYears: 1970-75Sold As: EACH2016 Monte Carlo Catalog Page: 194 click to enlarge ’70-75 Monte Carlo Authentically reproduced relayThis reproduction relay is identical to original equipment and is a must-have for any 4-speed vehicle. The relay works with the Transmission Controlled Spark (TCS) switch to advance the engine timing when the transmission is in top-gear, which provides better fuel economy. The original style relay is stamped with the original GM part number on its zinc-plated metal top and features a plastic body equipped with the correct 4-prong configuration. Sold per each. Search Keywords my car was a factory 3 speed on the tree I have converted to hei dist . Is this correct ???? do I need it any more???? can I just trace the wires back and cut them off ????? I thought it was a horn relay?????? car is apart for msd// carb// full tune and a few other things so I cant tell if disconnected everything will still work. thanks dave Quote Link to comment Share on other sites More sharing options...
stangeba Posted June 20, 2017 Share Posted June 20, 2017 Here is a picture of my 1971 350 4BBL with THM350 trans, NO A/C. I believe my TCS relay is on the right or passenger side (left on the picture) with the wires unhooked because I removed everything in 1972. I don't remember what the other relay thingy on the left or drivers side (rt. on the picture) is for. I don't believe you need any of it but make sure it starts and runs prior to cutting the wires. There should be some sort of fuse I would think but what, if anything else it powers, I don't know. Good luck, Bruce Quote Link to comment Share on other sites More sharing options...
dave m Posted June 21, 2017 Author Share Posted June 21, 2017 Hi thanks it is the relay you still have wires on facing the drivers side in the picture. it apers to be what opgi has in the pic but the discription does not make sense ??? Quote Link to comment Share on other sites More sharing options...
stangeba Posted June 21, 2017 Share Posted June 21, 2017 I don't remember, perhaps they are both related to the TCS (Transmission Controlled Spark) I will do some research, unless someone has the answer. Bruce Quote Link to comment Share on other sites More sharing options...
Mo's70MCs Posted June 21, 2017 Share Posted June 21, 2017 Does the car have A/C? If so I believe one is the TCS and the other is a blower motor relay. Quote Link to comment Share on other sites More sharing options...
stangeba Posted June 21, 2017 Share Posted June 21, 2017 Rod, the picture I supplied is from my 71 NO A/C 350 4bbl automatic. Bruce Quote Link to comment Share on other sites More sharing options...
stangeba Posted June 21, 2017 Share Posted June 21, 2017 Just found this wiring diagram in my collection of stuff. I can't be sure it is for first gen's but I believe it is. Looks like both relays / switches are for the TSC. Bruce Quote Link to comment Share on other sites More sharing options...
Mo's70MCs Posted June 22, 2017 Share Posted June 22, 2017 Imagine that a non a/c, 49 states, and possibly federal cars, with two spark control relays, and yet I speak from a 70's model and California emissions control perspective. Yet my 70's if I remember correctly only had an electricly controlled ported vacuum switch. I don't recall them ever having a accelerator control device other than an iddle stop solenoid. Controlling higher RPM for A/C compressor use. I stand corrected, you learn something new everyday. Quote Link to comment Share on other sites More sharing options...
stangeba Posted June 22, 2017 Share Posted June 22, 2017 Rod, If I recall correctly, the idle stop would energize in high gear, so when you took your foot off the gas, the throttle plates did NOT close to idle therefore the engine pulled less raw fuel, for lower emissions. Then why did it engage in REVERSE? I believe that was the only way to safely adjust the throttle position or RPM. The TCS system also only allowed vacuum to the vacuum advance canister when the vehicle is in high gear, or reverse (for testing). I picked up my car May 14. 1971 and I think the TSC was bypassed by June of 1971. As to what A/C vehicles were equipped with, I don't know. Bruce Quote Link to comment Share on other sites More sharing options...
dave m Posted June 22, 2017 Author Share Posted June 22, 2017 thanks for all the ideas no my car did not have ac//// it also did not have the throttle solenoid ( I did add a/c so I could use it now ) I'll worry about that later . Although it is busted I am going to wait to see iff everything works when the car is back together and then i'll either eliminate it totally or just plug it in and tape it up and hide it. thanks again Quote Link to comment Share on other sites More sharing options...
monte70car Posted June 23, 2017 Share Posted June 23, 2017 If it has the original trans take a look at the passenger side right by the kick down cable you will see a elec connection for the TCS on the transmission. Quote Link to comment Share on other sites More sharing options...
stangeba Posted June 23, 2017 Share Posted June 23, 2017 I took a picture of my trans TCS electrical hook up: Bruce Quote Link to comment Share on other sites More sharing options...
dave m Posted June 24, 2017 Author Share Posted June 24, 2017 thanks but my car always was stick shift factory 3 speed on the column now 4 on the floor . hoping to get everything back together tomorrow and then make sure every thing works without it dave Quote Link to comment Share on other sites More sharing options...
Sam (Bones) Posted June 25, 2017 Share Posted June 25, 2017 TSC, the '70 4 speed I had also used it Quote Link to comment Share on other sites More sharing options...
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