Back up lights on when trans is in neutral

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694spd

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I'm real near the complication of my car. Yesterday, I installed the battery to test the electrical systems and found that when I turned the key to the on position the reverse light under the dash and the ones in the tail lamps came on. The trans was in neutral at the time. I removed the back up light switch from the trans and found that the switch is made all the time. I would assume that the switch should be open when the ball on the end is not depressed. If so then it looks like my switch is the problem. I checked Rock Auto and they do not list one for a 1969 car, but they do list ones for 1970 and later.
Dose anyone know if the 70 and up switch is the same and that it will work in the 1969 trans?
 
The one they list for the 70 and up cars looks correct. It is a AIRTEX/WELLS 1S4938
 
I don't know if this switch is normally open or normally closed. A brake lamp switch is normally closed. The pedal pushes the button and opens the switch, pedal moved away release the button so switch returns to it normally closed position. Simple enough?
This reverse lamp switch should be easy enough to bench test with ohms meter, or even with battery live wires, inline fuse, and bulb.
 
I am pretty sure putting in reverse makes the circuit. Easy enough to tell, shift the trans into reverse and see if the linkage in the hole moves closer to the switch to engage it, or not.
 
I am pretty sure putting in reverse makes the circuit. Easy enough to tell, shift the trans into reverse and see if the linkage in the hole moves closer to the switch to engage it, or not.
Well of course reverse position closes the switch but... Is the button pushed or released when in reverse? That's what I don't know. I doubt the moving part inside the trans is worn. The button on the switch might be worn.
 
I just picked up a new switch at Advance Auto. BWD brand part# S9148 A cheaper looking unit compared to the factory one. The body of the switch has very little surface to put a wrench on it. I just installed it and it does work.
Just so everyone is clear. It is a normally open switch and when you put the trans in reverse the ball is pushed in and the switch is made turning the reverse lights.
 
The new cheaply made Chinese back-up light switch is already leaking on me. I just pulled it out for the 2nd time. The first time was to try to install a new o-ring as it was leaking around the threads. I was able to stop that but now it is leaking through the body of the switch. All these leaking problems and I have not even fired up the engine yet.
You can see the difference between the factory switch and the aftermarket switch in the picture. When the switch is just about seated in the trans. The 15/16" socket that I'm using is barley engaged with the flats on the switch due to the switch sitting in a recessed hole in the trans.

100_4356.JPG
 
The O-ring seems to just get crushed out of shape when tighten. They will either leak around the threads or through the body of the switch. Mine did both. I was able to stop the thread leak only to have the body leak.
I have been trying to figure out what the threads are. I thought that they might be NPT, but they do not look tapered. They may be 9/16" machine threads.
 
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