no reverse lights on 727 Transmission

[Gizmo327]

I picked up 1973 Cuda with the 727 Transmission and have no reverse lights. Not sure where to start trouble shooting or where to test. Is there a wiring diagram or suggestions on where or how to test to figure out where my problem is?

Thanks in advance

[Chryco Psycho]

there are 3 wires that go down to the trans , black on each side [reverse lights] & brown in the middle neutral start
1 of the black wires should have power & in reverse both wires should have power , the return black wire goes through the firewall under the kick panel to the rear of the car , start testing power at the connectors

[Cuda Cody]

Check what Chryco said, but also what transmission is in the car?  The rooster comb changed (I think around 69) so if you have a rebuilt trans and they used the wrong comb or you are running an early trans it might not work even with the correct wiring.

[7212Mopar]

Check the light bulbs And grounds?

[1 Wild R/T]

As Neil said the two outer wires are for the backup lights so put a jumper between them....
With the key on If the lights come on you are looking  either at the switch or the comb...
If they don't come on first check is for power, then bulbs

[Gizmo327]

Thanks for the info guys. I do have power at the plug and if I jump it I have reverse lights, but I had to wiggle my tester in the sockets and I noticed that the plug does not fit very tight so I'm thinking it might be bad contacts in the plug. Not familiar on how to use a tester on the switch so see if power goes through it. Might just run out and get more test jumpers try a few things


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[1 Wild R/T]

https://www.oreillyauto.com/detail/b/standard-ignition-5753/lighting---electrical-16777/connectors-sockets-16631/neutral-safety-switch-connector-11471/06e9829fd6d3/standard-ignition-3-terminal-multi-purpose-connector/s747/5820389/1971/dodge/challenger?pos=0

[Gizmo327]

Does not look like I'm getting power across the safety switch. Is there a way to test it when I get it out to know if it's the switch or the comb? I'm assuming transmission will need to be taken out to change the comb.


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[dodj]

You can test it with an ohm meter. On the bench depress the switch. With your ohm meter read across the two outside pins. Should have continuity.

[1 Wild R/T]

Comb is part of the valve body, it can be serviced in car...  Before jumping to conclusions know there have been a lot of defective aftermarket NSS's lately.. So new doesn't necessarily mean good...

Usually if the problem is related to the comb it's because the trans has been swapped and there simply is no comb present... 68 & earlier transmissions didn't use it...

If you pull the NSS you should be able to confirm the presence or lack of the comb...

One picture is the comb mounted on the rooster tail, other picture is the actual comb...

[1 Wild R/T]

One of the most common problems is the connection plug gets rock hard and doesn't make good connections... Hence my earlier link to a new connector

Testing the switch is best done with either a light or a DVOM with a buzzer mode... connect to the two outer pins and have a helper move the shifter in and out of reverse...  If you do it by yourself disconnect the shift linkage so you know it's not effecting the position of the comb, only the internal detents are positioning the comb...

[Katfish]

Good info, I have this same issue.

[7212Mopar]

https://forum.e-bodies.org/electrical-and-audio/11/neutral-safety-switch/5460/msg77642#msg77642

Take a look to see if this help.

[6pack]

I was pulling my hair out with this problem also.  The cure like stated above in the link is to go to Autozone; they are the only one I know for sure sell the correct size sensor.  All the other auto houses sell the wrong size for some reason.  They may work for other years.  I had the same issue as you wires and lights OK.

[wanderlustin]

Excellent thread and thanks to @7212Mopar for the link to a previous related thread.  Length of NSS is hopefully my problem too.  Reverse lights do not work, nor does grounding of the starter relay (I have an alligator clip installed for now and yes the car could crank over in any gear).