What did this wire do?

[Paul G]

It is a single brown wire in the loom with the transmission neutral safety switch wiring. It was plugged in to a round device that was scrwed on to the speedometer gear. Could it have been some type of electronic speed control?

[Nacho-RT74]

I can't find that on any 71/74 B body diagram, but searching in some C body diagram


NOTE... yes it looks is is a speed switch sensor and has to do something with Emission controls device onto firewall...

Not sure exactly how is but it look it is

Cali car ?

Pete ( TruckDriver ) had that device on firewall on his former 72 SE

[Paul G]

It was a California car originally.

[Nacho-RT74]

this is what I could find

Obviouslly bieng from a C body diagram, wires can run ( taped diff ) diff than on a B body.

TruckDriver's Charger got this device on firewall close where the ECU should mount

[Paul G]

Thats got to be it. S6-18BR. C body emission controls on a 72 B body. Must be because it was a California car. I did not think California had stricter emission standards way back then. I remember removing that hardware, control assembly and solenoid, from the fire wall a while back. Thanks Natcho.

[Nacho-RT74]

[4aThrill]

since that's the wiring harness part of your safety natural switch the brown wire should connect to the speed sensor that goes into the trans it will have a black wire as a ground. got the same thing on mine.

[John_Kunkel]

The single wire connects to the speed sensor for the NOX system, the speed sensor is a centrifugal switch that provides a ground at around 40 mph. Pic of the sensor which is threaded onto the speedo pinion adapter between it and the speedo cable.

[4aThrill]

thats the one

[Paul G]

I have that device. Removed it from the 727 when the A518 went on. The wire broke off at the case of the device on mine. Surpised it was for emmissions rather than speed control. 

[Rolling_Thunder]

I got one of those things too...    in my shed.   

[John_Kunkel]

Those switches are real handy for 518 swaps, just hook the transmission OD wire to the switch and presto...at 40 mph the OD engages.

[Paul G]

Wont work on a 3rd gen B body without major surgery. I could barely get the speedo cable back on. Too close to the cross member.

[John_Kunkel]

Wont work on a 3rd gen B body without major surgery. I could barely get the speedo cable back on. Too close to the cross member.

There's always a way.

[Paul G]

That might work. My speedo jumps around now a little bit. Probably due to the tight turns I had to put in it just to get mounted back on the trans. Is that an aftermarket device, store bought?

[John_Kunkel]

It's a Stewart-Warner piece but there are factory original as well, my '92 D350 5-speed had one.

[flyinlow]

Wont work on a 3rd gen B body without major surgery. I could barely get the speedo cable back on. Too close to the cross member.

There's always a way.

Wish I had seen that before I did surgury on my crossmember.