Help needed in identifying broken wire in 70 Corvette engine compartment

[Patrick B.]

While changing the intake manifold on my 70 Corvette I noticed a black wire from the engine harness hanging loose with the connector cut off. It exits the firewall wiring harness below the wiper motor and behind the distributor. I have taken a series of photos from an overview to the place on the harness where the wire emerges, and also a picture of the whole bundle of hoses and wires where the wire emerges with the wire marked with blue tape.

I would appreciate some '70 owners checking where this wire goes. This car has TI and no A/C but I'm sure the wire in questuion has nothing to do with the TI. It looks like it has been broken for a long time without an obvious effect. I'm guessing it may be part of the "TCS" system with I removed 40 years ago.

[Bill L.]

Re: Help needed in identifying broken wire in 70 Corvette engine compartment

I am leaning towards the TCS switch down on the trans if a 4 speed.

This is a unique connector like that on the brake fluid sensor wire.



Bill

[Monte M.]

Re: Help needed in identifying broken wire in 70 Corvette engine compartment

Patrick,
Take a look at page A8 of your assembly manual. It has the layout of the TCS wires.
Let me know what your regular e-mail is and I can send you some pictures of other 70 TCS70.jpgcars. The pictures are not great, but they my be a lot easier for you to make something out of because you have something to compare them to.
I do not have a 70, but I do keep quite a bit of stuff on the TCS system itself.

Best of luck,
Monte

[Patrick B.]

Re: Help needed in identifying broken wire in 70 Corvette engine compartment

Monte-- my email is patrick@drcriswell.com

[Monte M.]

Re: Help needed in identifying broken wire in 70 Corvette engine compartment

Sent in an e-mail with pictures. Will try to post pictures. Right now having a problem for some reason.
Patrick,
I know your relays is still on the wall. Maybe you can pull those wires out a bit so we can see where they go or where the ends of them are. That might help point us in a direction as well.

I know these are just a few pictures, but they may help a bit. If they do not help, send me a few more pictures of your wire and where it actually comes out of the harness. Turn that harness over so we can see if it does come out of the harness there.

Monte

[Monte M.]

Re: Help needed in identifying broken wire in 70 Corvette engine compartment

Patrick,
After looking at it, one of the other members (Bill) mentioned it looks like the trans switch control. I think he is correct.
1972 TCS Relay Jumper.jpg

This is a 72 sketch I did a while back, but the trans switch is the same. I looked on my 72 and my trans switch wire looks similar and comes out of my harness at the exact same point yours looks to. I think if you look into it further you will find that your wire is a bit short and is missing an end that plugs into the trans switch. (As shown the the page 8A diagram in the 1970 manual.

I will look for a picture of the end of that wire for you, or maybe one of the other members might have one.

Monte

[Monte M.]

Re: Help needed in identifying broken wire in 70 Corvette engine compartment

Patrick,

Here is a better diagram. It looks like the wire you are speaking of is the one called out as "TCS Time Delay Relay". It has a molded plastic end on it the actually covers the switch on the transmission.
One other thing: it says it is the "Time Delay". That is only on small blocks. The big blocks just have a jumper in its place. Even though some of the other relays on your car are not the same as the 72 drawing/schematic, the wire and trans switch are.

1972 TCS DIAGRAM.jpg

After all this, I sure hope your car is a $-speed, as Bill suggested, otherwise we have an interesting situation on our hands.

Best of luck,

Monte

Thanks, Bill for the help.

[Alan S.]

Re: Help needed in identifying broken wire in 70 Corvette engine compartment

Hi,
Here's the transmission switch and connector from my 71's CEC system.
I don't know if the 70 connector is the same.
Regards,
Alan

[Patrick B.]

Re: Help needed in identifying broken wire in 70 Corvette engine compartment

Patrick,

Here is a better diagram. It looks like the wire you are speaking of is the one called out as "TCS Time Delay Relay". It has a molded plastic end on it the actually covers the switch on the transmission.
One other thing: it says it is the "Time Delay". That is only on small blocks. The big blocks just have a jumper in its place. Even though some of the other relays on your car are not the same as the 72 drawing/schematic, the wire and trans switch are.

[ATTACH=CONFIG]60334[/ATTACH]

After all this, I sure hope your car is a $-speed, as Bill suggested, otherwise we have an interesting situation on our hands.

Best of luck,

Monte

Thanks, Bill for the help.

Monte -- The car is a 4 speed small block LT-1. The big block in the picture is a real ZL-1 (out of one of those 69 exotic Camaros) that I put in it in the early 80's. I was putting a 71 LS-6 low rise manifold on it so I could put my original LT-1 hood back on.

The remnants of the black wire look a lot like the transmission switch wire in Alan's photo. I removed the TCS stuff the first week I bought the car because blocking the vacuum advance didn't seem like a good idea. I think I still have the components somewhere, and I would have disconnected wires rather than cut them. If the cut wire is the transmission switch wire, it could easily have been pinched off during one of the engine or transmission removals and replacements I performed over the years. The wire in question exits the main bundle under the wiper motor directly beside a branch of the bundle going to the passenger side of the engine compartment (possibly for the heater blower). I will try to identify where that branch goes tommorrow. If the transmission switch wire in your cars exit the engine harness at the same point it will verify the identity of my broken wire.
Thanks fellows.

[Alan S.]

[Harmon C.]

Re: Help needed in identifying broken wire in 70 Corvette engine compartment

I had a black wire that came from the harness and was a ground for the wiper motor. My wipers had a bubba ground as the wire was burned off inside the harness.

[Patrick B.]

Re: Help needed in identifying broken wire in 70 Corvette engine compartment

The wrapped wires exiting the harness adjacent to the cut wire turned out to be the wires meant to attach to the TCS solenoid. I'm pretty sure that the cut wire was meant to go to the transmission switch.

[Russ S.]

Re: Help needed in identifying broken wire in 70 Corvette engine compartment

Patrick, You are correct. I am working on a 70 with a very closely related problem. I think your issue has been answered so I hope you don't mind my hijacking your thread. On the first picture you posted there is a small rectangular box mounted to the firewall just a few inches to the driver side of the w/s wiper motor. It has three terminals. Two of the terminals get connected to a "two wire" connector. The third terminal is directly behind the forward top terminal. I put a new engine compartment harness in and there is no wire to connect to the third terminal. Can you tell me what color the wire is for that position? Also what is this little box for? Last question, where does this third terminal wire come from?

The wrapped wires exiting the harness adjacent to the cut wire turned out to be the wires meant to attach to the TCS solenoid. I'm pretty sure that the cut wire was meant to go to the transmission switch.

[Monte M.]

Re: Help needed in identifying broken wire in 70 Corvette engine compartment

Patrick,
Have you looked into the other wires any further? If any of the other wires were cut, maybe one of the other member can measure the lengths of the wires for you so you can make the needed repairs.

I do not want to hi-jack your thread either, BUT:

When I bought my 72, the previous owner took the plastic connectors off the TCS components and tucked the wires back into the harness without hurting them or removing the actual wire connectors. My car too had one wire sheered off over the years. It is a very easy one if I can ever figure out the length it originally was.

It is the tan wire the goes from the TCS switch to the fast idle solenoid. Maybe there is a 72 owner out there with that wire in tact than can measure it for me?

Russ,
Do you have a 1970 wiring diagram for your car. If not, you might do a search on this forum, or just start another tread asking another member, that has a diagram to check out those wires for you. My 72 wiring diagrams are no help to you at all.
Also, there are a number of other threads on the TCS/CEC systems that might be able to help you out.
When I started my research on my car, it seemed that everything I found back then was on 1970 and 1971.
Best of luck,

[Russ S.]

Re: Help needed in identifying broken wire in 70 Corvette engine compartment

The 70 service manual says on the cover "and 69 corvette" Is there also a 70 manual that covers a 70 corvette? The 70 manual with the 69 vette has different wiring than the 70 I am working on.