71 RR ignition switch to harness

[SMS68]

1971 Road Runner wiring riddle.

I’m rebuilding the steering column and noticed something doesn’t match the wiring diagrams.

The old ignition switch doesn’t have the ”18V Ground” conductor going down to the connector. It’s not cut off or removed…it’s just not there. The new switch does have it.

On the harness side, the diagram shows no pin/conductor in the corresponding position. It’s blank. What good is the 18V Ground if it’s not connected to anything? However, my harness has an orange conductor pinned into that spot and it’s not an add on, it’s wrapped/taped into the bundle.

Anyone have a clue what’s happening here?

 

[Ronnman]

I believe the Orange wire from the dash side is the instrument lights feed and would be for the column shift indicator light, if equipped. These harnesses were used in some instances across vehicle platforms and sometimes the wiring is different from that shown in the manuals.
Ron

 

[SMS68]

I believe the Orange wire from the dash side is the instrument lights feed and would be for the column shift indicator light, if equipped. These harnesses were used in some instances across vehicle platforms and sometimes the wiring is different from that shown in the manuals.
Ron

That would definitely make sense…so in this case I definitely don’t want to connect it to a ground coming from the switch. Perhaps I need to pull the ground from the switch side of the connector and ground to column?

 

[Ronnman]

I would use a meter to verify power at the orange wire with instrument lights on. I would also verify that the column “ground” wire is in fact connected to ground. If both of these are powered and grounded respectively, you will definitely need to eliminate one connection to prevent a direct short when the instrument lamps are on.
Ron

 

[SMS68]

Found my answer here:
Loose wire

Linking in case anyone experiences the same in the future.

Thanks @72RoadrunnerGTX !

 

[pnora]

You do not need it.

 

[SMS68]

I would use a meter to verify power at the orange wire with instrument lights on. I would also verify that the column “ground” wire is in fact connected to ground. If both of these are powered and grounded respectively, you will definitely need to eliminate one connection to prevent a direct short when the instrument lamps are on.
Ron

Thanks. That’s exactly what I was concerned about.

It appears the 18 gauge ground is in fact unused and can be pulled from the connector and taped off. Found a related post above. This place is a great resource!

 

[Ronnman]

Thanks. That’s exactly what I was concerned about.

It appears the 18 gauge ground is in fact unused and can be pulled from the connector and taped off. Found a related post above. This place is a great resource!

Glad you got it figured out. That would have been fun to troubleshoot since it only grounds when in the crank position! 72RoadrunnerGTX as well as many others, are a great resource and have helped me on various issues in the past.
Ron

 

[72RoadrunnerGTX]

Found my answer here:
Loose wire

Linking in case anyone experiences the same in the future.

Thanks @72RoadrunnerGTX !

Was just about to post that picture again.
In this case I would have to assume a rare error in the ’71 factory wiring diagram. Haven’t seen a 18ga violet wire (18V) in that position. The later c-body ignition switch with a black wire there, grounds while cranking, is connected to the brake waring light circuit on c-bodies, bulb check I assume.

The ’72 wiring diagram would be correct for the ’71, an orange wire in that position normally on the dash harness side, dash illumination, gear selector back lighting for column shift autos. If the later switch is used without the modification documented, the illumination fuse will blow the first time the car is started with the lights on.