1970 LT1 Firewall Wiring and Vacuum Questions

[David S.]

Hi All,

Finally got the LT1 back on the road. I have few questions regarding wiring/ vacuum on the car.

1 - The engine compartment wiring harnesses were changed. As the pictures show below, I have a green wire coming out of the harness near the heater box (below the wiper door actuator) that does not connect anywhere. What does this go to?

2 - On the driver side of the firewall, between the master cylinder and the motor, I have two wires that come out of the harness that have clips. The clips do not go into anything. Can someone advise what they are?

3 - The last picture I show is of a vacuum hose coming through the firewall. This is the only vac. hose that does not lead anywhere. Can someone advise what it is?

IMG_0117.jpgIMG_0118.jpgIMG_0120.jpgIMG_0121.jpgIMG_0122.jpg

Thanks!
Dave

[Edward J.]

Re: 1970 LT1 Firewall Wiring and Vacuum Questions

Hi All,

Finally got the LT1 back on the road. I have few questions regarding wiring/ vacuum on the car.

1 - The engine compartment wiring harnesses were changed. As the pictures show below, I have a green wire coming out of the harness near the heater box (below the wiper door actuator) that does not connect anywhere. What does this go to?

2 - On the driver side of the firewall, between the master cylinder and the motor, I have two wires that come out of the harness that have clips. The clips do not go into anything. Can someone advise what they are?

3 - The last picture I show is of a vacuum hose coming through the firewall. This is the only vac. hose that does not lead anywhere. Can someone advise what it is?

[ATTACH=CONFIG]70213[/ATTACH][ATTACH=CONFIG]70214[/ATTACH][ATTACH=CONFIG]70215[/ATTACH][ATTACH=CONFIG]70216[/ATTACH][ATTACH=CONFIG]70217[/ATTACH]

Thanks!
Dave

Dave, green wire is for a temp switch on pass side cylinder head,( below cylinder head) for CEC system, It appears it the picture of the pink and black wires that they plug together?, the vacuum hose is just a vent hose for the vacuum switch under the wiper grill.

[David S.]

Re: 1970 LT1 Firewall Wiring and Vacuum Questions

Hi Edward,

Thank you.

1 - Just found an NOS TCS Sending Unit for the cylinder head. That should be an easy fix. Now, I assume the trans plug should have a wire on it which I need to validate. Also I don't recall if the TCS solenoid by carb has wires going to it.

2 - Regarding the two connectors, I thought they could plug into each other. But it would seem odd that two wires coming out of the same harness plug into one another? Everything on the car works (less the washer pump). I don't like to plug and play without knowing for sure or testing first.

3 - Thank you.

Best,
Dave

[Edward J.]

Re: 1970 LT1 Firewall Wiring and Vacuum Questions

David, yes the trans switch is what activates the solenoid, my C3 is a 72 its a little different the 70, yours emission system is TCS mine is called CEC , just slightly different. If you have AIM or shop manual they may show the two wires.

[Ralph S.]

Re: 1970 LT1 Firewall Wiring and Vacuum Questions

Dave, There are 2 wires together that go down to the transmission back up light switch.

[David S.]

Re: 1970 LT1 Firewall Wiring and Vacuum Questions

Hi Ralph,

Understood. I'm sure its hooked up just need to confirm.

Can you send me reference pictures of your LT1 regarding the two wires with connectors that do not go anywhere? Can you confirm they clip into each other?

Thanks,
Dave

[David S.]

Re: 1970 LT1 Firewall Wiring and Vacuum Questions

Bringing this to the top.

Still trying to figure out what the two clips go to?

Thanks!
Dave

[Ralph S.]

Re: 1970 LT1 Firewall Wiring and Vacuum Questions

What Clips ? post a picture

[Dave S.]

Re: 1970 LT1 Firewall Wiring and Vacuum Questions

Dave, There are 2 wires together that go down to the transmission back up light switch.

The back up light switch is not part of this. Ed mentions the transmission TCS switch which is a switch screwed into the side cover and has 1 wire going to it. I believe it's black and has a plastic push on connector onto the switch. That switch is activated when the car is in third of fourth gear (or both?) and activates the TCS switch. It can be very confusing.

[Mike F.]

Re: 1970 LT1 Firewall Wiring and Vacuum Questions

2 - On the driver side of the firewall, between the master cylinder and the motor, I have two wires that come out of the harness that have clips. The clips do not go into anything. Can someone advise what they are?

Are your back up lights working? If not, that may be the plug.

25-103972-1.jpg

[David S.]

Re: 1970 LT1 Firewall Wiring and Vacuum Questions

The backup lights are working. Switch installed correct as well.

Can anyone share reference pictures of the above wires/clips?

Thanks,
Dave

[Alan S.]

Re: 1970 LT1 Firewall Wiring and Vacuum Questions

Hello Dave,
After looking at the additional photo you sent here's what I think based on THIS photo:
First a question: notice how the TCS relay is mounted in THIS picture compared to yours….which would be typical of production?
Second, notice the unused spade terminal on the RELAY in YOUR picture. Is that the connection for one of your unused connectors?
Third, notice the connection near the harness in THIS picture… is that the second of the unused connectors in YOUR first posted picture? Is there another female connector laying near the harness that you haven't seen yet?
Regards,
Alan

[David S.]

Re: 1970 LT1 Firewall Wiring and Vacuum Questions

Alan,

Thank you, very helpful.

I'll check it out!

Thanks,
Dave