# 1970 GTO Dash Wiring Help



## scolmoo (Mar 17, 2014)

Hello all. Newbie here but have been a member quite some time on LS1GTO. Figured it was time to make an account for collaborative problem solving. Been working on getting my Dad's 70 GTO back together after it has sat for a decade or so mid restoration. It's sat so long he doesn't remember exactly where stuff goes, is, or how it went together. Installed the dash today and was working on wiring when I ran into a cross roads. Pouring over wiring illustrations has me cross eyed and no closer to a solution it seems. New dash harness compares identically to the old one aside from less splices (LOL). Car was an original 4spd car that was converted to an Auto and now being converted back.

As it sits I have these three connections:









I think I finally ruled the Pink/Orange one as Auto only downshift switch. However, I still have the pink/green horizontal one and the double purple stacked one.

I have this connection on the steering column which I am not sure what it's for and can't seem to find it anywhere:









And then there is this connection for the clutch safety:









1.The three connections I have will in no way reach the clutch safety and there doesn't seem to be a wire(s) on the left side of the harness/column to go here. Anyone know which it is or can take pictures of theirs to compare?

2. The double purple, which is listed on some diagrams as neutral safety, was wired together and went to the side of the 4spd. on another connector. I assume as a bypass but obviously not correct.

3. Does the pink/green go to the connector on the column?

Appreciate any help and look forward to working with you all as I am sure it's going to be a long road ahead...:willy:


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## 05GTO (Oct 6, 2004)

I believe the Green/Pink wires go to the reverse light switch which may be on the transmission, the purple pair can connect to the clutch safety if you don't have a neutral switch on the transmission.


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## scolmoo (Mar 17, 2014)

Neutral switch may be on the side of the 4speed as that is where the connection went on the factory harness to a connection/sensor on the side, albeit like stated above the 2 wires were spliced together.

Does nothing need to connect to the sensor on the clutch? Seems odd that something wouldn't go there, but the new harness is the same as the one that came out and I see nothing there either.

There isn't enough length on the green/pink connector to go anywhere but within 6 inches of where it hangs down beneath the dash. Not trying to discredit you or anything, I just don't see how it could connect to the transmission. 

Maybe it will just have to wait until further along in the drivetrain install to match everything up/trouble shoot.


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## 05GTO (Oct 6, 2004)

scolmoo said:


> There isn't enough length on the green/pink connector to go anywhere but within 6 inches of where it hangs down beneath the dash. Not trying to discredit you or anything, I just don't see how it could connect to the transmission.


Is it possible that you have a wiring harness for an automatic transmission, the neutral safety and reverse lamp connection(s) on an automatic plug into the switch on your steering column shown in one of your pictures. When doing a 4-speed conversion the neutral safety/backup light switch on the column is not used and your reverse lights connect to the transmission and the neutral safety switch connects to the clutch safety switch.


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## scolmoo (Mar 17, 2014)

After hours of searching online I found a few good restoration picture collections and finally found what I was looking for.

I believe you are correct in that the connector on the column is only used for automatics. This pictures shows the two horizontal ones I was questioning dangling and the double purple going to the clutch sensor. Hopefully the reverse light connector to the transmission is on the rear light harness somewhere. LOL

Appreciate the assistance!


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## jmt455 (Mar 26, 2012)

Double purple is the "neutralizer" switch connector (Clutch safety interlock switch). As you discovered, it connects to the 2-wire connector on the clutch pedal bracket.

The Park/Reverse switch on the column should be active on your car. The column Park/Reverse function is engaged by the "back-lock" linkage, which is designed to engage the column locking mechanism when you put the transmission into reverse.

There should be a bell-crank and rod linkage that connects your reverse shift lever on the transmission to the lever at the bottom of the steering column. The column/shifter linkage was designed so that you had to put the car in Reverse to be able to rotate the ignition switch to the locked position.

The back-up light connector should plug in to the park-reverse switch on the column. It is the semi-circular switch, down near the floor (shown in the second image you posted).

HTH


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## scolmoo (Mar 17, 2014)

Gotcha. Thanks for the assistance! 

Haven't run the rod linkage to the column yet as the transmission isn't close to being installed yet. Just getting ahead of myself in regards to trying to find a place for everything when not everything is there.


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## 1970mint (Oct 27, 2015)

Did you ever figure out the reverse/back up light circuit?
My lemans was a factory 3spd manual that was changed to a m21 along the way. So I should have a linkage from steering column to m21 reverse linkage??


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## Rukee (Feb 8, 2007)

Mine had a harness that plugged in under the dash went through the firewall down to the tranny.


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## 1970mint (Oct 27, 2015)

What year is yours?
Do you have munci?
Is it a linkage type switch?
Or on base of shifter?


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