TCS Relays P&A

[Tom R.]

I've perused the archives and browsed my 75 and 83 P&A catalog and while I find part numbers...can't say there was much consistency.

I've conclude the relays used for TCS from 70-74 were used to accomplish five different functions with two of those used in 71 and discussed in a recent thread. That leaves us with 70, 72, 73 and 74.

The 70 relay 3961573 appears to have been used for spark control.
The 72 relay 3996297 was used for vacuum advance delay.
The 73 relay used also in 74 6270698 was used for spark delay.

I think I have this right but why in the P&A does it mix the tranny switches with electrical and relays with the tranny section...seems confusing.

[Juliet P.]

Re: TCS Relays P&A

I can offer up a little bit of information on this regarding 1970. The TCS system included a relay on the Tranny as well as the one on the intake which controlled the vac advance. It prevented advance until the car was heated up and also in a higher gear. There's a wire which goes to the intake relay which comes out of the harness just below the wiper door vacuum actuator. There's another which goes to the relay on the TH400 tranny. I'm not certain of the setup on 4-spds. I believe both conditions need to be met in order for vac advance to be permitted. Mine isn't 100% hooked up yet. The intake part was common on Camaro's also. I got a used original from a Camaro parts dealer (for about half of what the vette parts dealers wanted). ~Juliet




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