Greg Rogers

I'm in the process of redoing the a/c on my 71 Cutlass and while doing it I decided to fix a few other small things. Years ago I found a electrical plug that wasn't connected to anything under the car by the drivers side of the transmission. It comes off the harness that has the smaller wires to the starter. After sort of checking into I it, I think I determined that it was the wire to the pressure switch for the transmission controlled spark which is actually on the passenger side of the trans between the kick down cable and the dipstick tube. The pressure switch has never been there since i've owned the car and has a plug in it's place. So I did some research and bought what I thought was the correct pressure switch thru ebay. This switch has 2 terminals which are together like this = with a rivet .. I mean that they aren't 2 separate terminals but 1. Anyway I went to install the switch and found that the plug has 2 wires that are like a T or one terminal is horizontal and one is vertical. So I found the original part # for this switch is 6462514. I found a couple of these on ebay and they just have 1 terminal and it looks just like a oil pressure (light) type switch. So.... I am confused. Maybe this plug isn't even for the TCS?? Can anyone help with this?? Appreciate it... Greg

MDchanic

I don't want to bust your chops, and you certainly have the right to do whatever you wish to your car, but the TCS was a bogus piece of emissions equipment and the car will run better, perform better, and get better gas mileage without it, provided you set the timing to where it should be, instead of where the manual tells you to set it.

I'd save my money and my sanity for a different project.

- Eric

Greg Rogers

I know what you're saying. I actually was just going to use the switch as a connection for the wire. (just a place to put it) But after checking in to it and getting more confused , now I'm confused what this wire connection is for..??. Thanks

MDchanic

The TCS switch on the transmission opens when the transmission is in third (top) gear.

This moves the valve on the DVCS from the position that connects the distributor to the atmosphere (defeating any vacuum advance) to the position that directs ported vacuum from the carburetor to the vacuum advance (that is to say that in first and second gears it defeats the vacuum advance and retards your ignition).

The DVCS also redirects manifold vacuum to the vacuum advance, instead of ported vacuum, when the engine begins to overheat (around 215°), thus advancing the timing at idle (which is to say, stuck in traffic).

If you like your car to run retarded, then this is the emission control for you.
If you like your car timed properly, then this is a bunch of unnecessary garbage
(though, if your engine prefers ported vacuum, as some do, then the switch to direct manifold vacuum when the car gets hot might be helpful).

- Eric

Allan R

The wire goes to the distributor to advance the timing when the car is in 3rd gear, or when overheat conditions arise. If you have a 71 CSM it's all explained on page 6K-9.

As Eric pointed out, it's an early form of emissions control. I have it in my car and it runs just fine. I have some spare TCS's if you run into a bind and really need one.

joe_padavano

Let's back up a little, because I'm not exactly sure of the O.P.'s question. First, your trans a TH350. The harness in the car is designed to accommodate both the TH350 and the TH400, and the TH400 requires two terminals in the harness, one for the TCS and one for the kickdown. That's why the plug has two terminals in a "T" configuration. The TH350 only uses one of them (the green wire).

The plastic connector that snaps into the trans body can have either one or two terminals, but only the one for the TCS will be used in the TH350. Again, GM designed the cars to be able to accommodate either trans. Just be sure the the pressure switch inside the trans is connected to the correct terminal on the case connector.

Greg Rogers

Yep Joe you are right and I found your answer to it on another older thread about a kick down switch. I was confused because there was 2 connectors in the wire socket and the TCS switches that I found only had 1 connector. Now after checking the shop manual and your responses to this and the other thread I see that only 1 terminal is used on the th350 (for TCS only) and both are used on a th400 for kickdown and TCS. Mystery solved.. Allen, I have the switch you pictured. I wanted to get the one that is down on the Right side of the trans which looks like a light oil pressure switch. Eric, I know what you mean about loosing my sanity messing with this stuff but there has been some things I cobbled up years ago, and now I am going back and correcting. Actually it's kinda fun figuring this stuff out. And I agree with you- I wont be using the TCS but I am going to try to make it look like it's as it was from factory but still have vacuum advance in all gears.. Thanks again guys.