1970 TCS Switch

[Deane M.]

Re: 1970 TCS Switch

As usual, ask the question, get the answer. You guys are great! Some excellent advice and answers. Terry, thanks for the heads up, and Doug, thanks for the site. They clearly have what I need. Just have to determine which type although I'm pretty sure it is the pin type.
Thanks again to all.

[Terry M.]

Re: 1970 TCS Switch

One of my parts books shows the 70-71 switch on trans as being P/N 6462286 (GR-4.075, 2.408) for the turbo 400 and P/N 3961567 (GR-2.408) for the manual trans, if I am reading it correctly.
Lynn

I see the 3961567 in the 70 AIM on page K204 UPC 7 Sheet B6.

The 3961567 is the pin style 4-speed TCS switch. I am off work for the next few days and will check the 1971 & 1972 AIM to see where the switch changed. We ought to have something in the TIM&JG about this since the configuration of the 4-speed switch terminal is easily judged by the Chassis crew.

[Edward J.]

Re: 1970 TCS Switch

Terry, Sounds Logical To Me, There Are Two Wires On Connector I Thought One Was Ground And The Other Power For For Kick Down Solonoid.

[Terry M.]

Re: 1970 TCS Switch

That ground one would be for the TCS switch. It picks up a ground when the line pressure is higher than the set point. One of the ways of testing the transmission part of the system would be to ground that wire at the connector. Of course reverse with the engine running is easier than crawling under the car. The temperature part of the system can be tested by grounding the green wire at the passenger side head temperature sensor.

[Lynn H.]

Re: 1970 TCS Switch

The 3961567 is the pin style 4-speed TCS switch. I am off work for the next few days and will check the 1971 & 1972 AIM to see where the switch changed. We ought to have something in the TIM&JG about this since the configuration of the 4-speed switch terminal is easily judged by the Chassis crew.

Terry-
Looking at the AIM drawings for 70, 71, 72, it appears that 71 used the same switch (at least for the manual trans) as 70, P/N -3961567, which looks to be the pin type of switch. The 72 Aim shows the switch as P/N 3996286 (4 spd?). I see in 71 although the same switch was used, they used two relays. P/N 3990842 (Relay Reversing), and P/N 3990843 (Relay-Delay), where in 70 only one relay was used P/N-3961573.
I just had a look at my 72-4 spd and the 72 switch (3996286), is a spade connector type, although it looks to be installed in the same way as the earlier pin type of external switch. I also see in the 72 AIM, that only one relay was used (P/N-3996297, Relay-Delay).
Lynn

[Terry M.]

Re: 1970 TCS Switch

Thanks for researching the AIMS. It saves me an extensive visit to the cold storage.

Those delay switches are a real quagmire. In the PV manual I tried to sort out which year(s) and engines had the delay, but while I think I was mostly right I wouldn't want to have my well being depend on the accuracy of them. The CSM (Chassis Service Manual) contains the delay data for ALL Chevrolet body lines, and extracting just the Corvette information is tricky.

I am sure there was no delay in 1970. I know either 1971 or 1972 had a shorting bar or wire at the delay switch connections for one of the motors -- the AIM shows this, but finding it requires the diligence of Sherlock Holms.

[Lynn H.]

Re: 1970 TCS Switch

No problem, I know that right now in my area (and I believe yours too), cold storage is exactly that -COLD!!!
I also understand what you mean by the "Sherlock Holmes", as finding info in the AIM's can be frustrating at times, due to the way it seems to jump around. You would think someone would have put ALL relevant information in the same general area. I have always assumed that it had more to do with the sequence in which the cars were assembled, and certainly NOT for the ease of the restorers 40 years later.
As far as extracting the Corvette info (as well as that of other models), I can relate to that somewhat also. I still have not had the time to figure it all out on the 70 Caddy (which I had started a thread on a month or so ago). While I am under the belief that ALL the systems were intended to serve the same function (I may be wrong on this), I am experiencing some of the different components and set-ups used. The Caddy has a thermal switch that seems to be MUCH different from that on the systems in the Corvette's. While I think I remember you stating that there is some sort of temperature switch on the Corvette system, the one on the Caddy has 5 vacuum ports, and seems to be more complicated. I think this has more to do with the automatic climate control in that car, than the way the system itself is designed to function.
Being as that I have the 70 and the 72, along with the Cadillac with the TCS, this is a subject of much interest to me, as I would like to have them all working properly if possible.
Lynn

[Terry M.]

Re: 1970 TCS Switch

No problem, I know that right now in my area (and I believe yours too), cold storage is exactly that -COLD!!!

Amen Brrrr....

I also understand what you mean by the "Sherlock Holmes", as finding info in the AIM's can be frustrating at times, due to the way it seems to jump around. You would think someone would have put ALL relevant information in the same general area. I have always assumed that it had more to do with the sequence in which the cars were assembled, and certainly NOT for the ease of the restorers 40 years later.

I am told that is exactly how the AIMs are laid out -- sequence of build.

As far as extracting the Corvette info (as well as that of other models), I can relate to that somewhat also. I still have not had the time to figure it all out on the 70 Caddy (which I had started a thread on a month or so ago). While I am under the belief that ALL the systems were intended to serve the same function (I may be wrong on this), I am experiencing some of the different components and set-ups used. The Caddy has a thermal switch that seems to be MUCH different from that on the systems in the Corvette's. While I think I remember you stating that there is some sort of temperature switch on the Corvette system, the one on the Caddy has 5 vacuum ports, and seems to be more complicated. I think this has more to do with the automatic climate control in that car, than the way the system itself is designed to function.

The Corvette temperature switch is in the passenger side head -- between cylinders 6 & 8. It has two connections in an L shape. One connects to ground below some temperature (I have the number in the PV manual. 86* sounds right but that is a guess) and the other terminal connects to ground above 230*. So if all the components are properly working (a big IF) the ground signal from the temperature sender gives full vacuum to the distributor on cold start, and again if the engine overheats. In the normal operating heat range ther is no ground from the temperature switch.

You are probably right that the vacuum ports on the Cadillac is due to the automatic climate control system. That would add an additional level of complexity to the system. Do you have a FSM for that car? It might contain some answers.

Being as that I have the 70 and the 72, along with the Cadillac with the TCS, this is a subject of much interest to me, as I would like to have them all working properly if possible.

Lynn

No offense, but good luck. I have talked a lot of Corvette owners through the TCS system, but I wouldn't touch that Cadillac with a ten foot pole -- and I love Cadillacs. I have a 1937 project. Not much vacuum, but the headlight system in that car is worthy of those old engineers.

Terry

[Lynn H.]

Re: 1970 TCS Switch

I was able to come up with an original 1970 Cadillac FSM, and it spells things out fairly well. The jumping around from one project to the next has kept me from troubleshooting the system as of yet, not to mention that COLD factor we have right now. I do not have room for this car in a heated area, so it may be a while before I actually get to it. It seems to be causing me a dim GEN light when the solenoid on the intake is plugged in (electrically). It was unplugged when I got the car earlier this year, and I wanted to see if I could make it work properly before passing this car on to the next guy. Here is a picture of the Cadillac setup from the FSM for comparison.
Lynn

[Lynn H.]

Re: 1970 TCS Switch

This is where I purchased my replacement TCS switch. They are difficult to find.

http://www.thepartsplaceinc.com/ocat...D=10&curpage=3

Scroll down to part #
EL8426Z

Douglas,
After going to look at my 72 4 speed this morning (which is the EL8426Z, spade connector style, GM#3996286), I noticed mine had the spade broken off. I went to this site and found the correct part, as well as seen some of the other TCS parts they have available, such as solenoids and relays. I did notice that they do not list it specifically as a Corvette application, but they do list the correct GM part number cross reference from the AIM numbers. I ordered a switch for my car for what I thought to be a very reasonable price of $32. I am assuming that Deane (original thread starter) has a '70 4 speed car and the correct number for his part is the EL8427Z GM#3961567, this is the pin style of connector. I thought these parts would be much more difficult to locate, and thank you for posting this information. I would suggest anyone else who has an interest take note of this supplier, as it looks like they have quite a variety of hard to find parts for various GM vehicles, including the Corvette.
Thanks!!!!
Lynn

[Lynn H.]

Re: 1970 TCS Switch

Terry-
Looking at the AIM drawings for 70, 71, 72, it appears that 71 used the same switch (at least for the manual trans) as 70, P/N -3961567, which looks to be the pin type of switch. The 72 Aim shows the switch as P/N 3996286 (4 spd?). I see in 71 although the same switch was used, they used two relays. P/N 3990842 (Relay Reversing), and P/N 3990843 (Relay-Delay), where in 70 only one relay was used P/N-3961573.
I just had a look at my 72-4 spd and the 72 switch (3996286), is a spade connector type, although it looks to be installed in the same way as the earlier pin type of external switch. I also see in the 72 AIM, that only one relay was used (P/N-3996297, Relay-Delay).
Lynn

I just received the TCS switch for my 72 4 speed car (3996286) from "The Parts Place Inc.", the place that Douglas posted the link for above. I thought I would post a photo of it. This is the spade connector style for 72. It came in a generic looking box with the number DQ-0305, although it is stamped on one of the hex flat surfaces with the GM number 3996286. I tried to show this in the photo, but I think with the glare it does not show up well.
Lynn

After getting the spade style switch today, I got to thinking about a part I had acquired some time ago that was tagged Muncie reverse light switch. When I went out to look at it I discovered that this was the 70-71 pin style TCS switch, so I thought I would add a photo of this part also. I do not know if this is the Generals part or aftermarket, but it has the numbers 502F, on the crimped edge (I think you can see them somewhat in the photo). It also has the GM #3961567 molded in the plastic radially around the face with the pin. There is also a small number 7 on this face also, separate from the P/N.

[Stephen B.]

Re: 1970 TCS Switch

eBay has TCS parts quite frequently.