Reverse Lights

[72 Electric Blue]

Whether my car is in drive or reverse the reverse lights are on.  When in park or neutral the reverse lights are off.  Any suggestions on how to fix it?

[GoodysGotaCuda]

Sounds like the neutral safety switch needs adjustment, replacement, or the wiring inspected. The reverse light circuit runs through the switch.

[burdar]

Sounds like the neutral safety switch needs adjustment, replacement, or the wiring inspected. The reverse light circuit runs through the switch.

 

Inspect the wiring and make sure all the wires have continuity.  Pull the NSS and inspect.  You may have to drop the trans pan and have a look at the valve body where the contacts for the NSS are.

[72 Electric Blue]

Whether my car is in drive or reverse the reverse lights are on.  When in park or neutral the reverse lights are off.  Any suggestions on how to fix it?

Thanks.  I'll look at the NSS.

[Skunkworks Challenger]

 May I join the party?  I am in the initial stages of conducting "sea trials" on my newly minted 70 Challenger with a 727 and discovered that my back up light is on in any position except park and neutral .  So, I'm very interested in what anyone knows about the problem and how to resolve it.  I read  an earlier post that mentioned "adjustment" in relation to the switch.   How would one adjust the switch? PK

[dodj]

The only way to 'adjust' the nss is to put another gasket or two on the switch before installation to prevent the switch from going in as far. The nss turns on the (contacts close) when the lever in the trans (VB-1) depresses the switch. It seems to me the switch is depressed too much in all positions. Try unscrewing the nss a turn or two and see how your back-up lights behave. 

[Skunkworks Challenger]

May I join the party?  I am in the initial stages of conducting "sea trials" on my newly minted 70 Challenger with a 727 and discovered that my back up light is on in any position except park and neutral .  So, I'm very interested in what anyone knows about the problem and how to resolve it.  I read  an earlier post that mentioned "adjustment" in relation to the switch.   How would one adjust the switch? PK

I tested my switch and two spares---found the switch not to be the problem.  I removed the switch and looked in the hole at the cam.  The cam is perfectly in the middle of the hole but the notches seem out of sync with the gear selector .  It looks fine for park, reverse and neutral but for drive, 2nd and 1st the cam appears too far back to contact the switch.  I tried two gaskets and no gaskets to no avail.  Looks like i'll have to pull the valve body and check out the cam.  Anyone have experience with this problem?  PK

[dodj]

 It looks fine for park, reverse and neutral but for drive, 2nd and 1st the cam appears too far back to contact the switch.  I tried two gaskets and no gaskets to no avail.

For drive 2nd and first it should be too far away to depress the switch. Park and neutral should line up with metal for the centre pin on the switch to contact ground for the start relay. When the gear selector is in reverse, the cam needs to depress the switch enough for the contact to close between the outer two pins. Try putting the selector in reverse, then screwing in your nss switch until the contact closes.

[Skunkworks Challenger]

 Thanks, I'll try that but I thought that the contact had to be depressed to break continuity, keeping the light off.  PK

[dodj]

Thanks, I'll try that but I thought that the contact had to be depressed to break continuity, keeping the light off.  PK

Sorry Skunkworks, I wrote that all backwards.   You are correct. Depressed to break the contact. Guess I've been thinking about those switches backwards for years.  Give me a minute and I will measure how far back that lever should be on a spare 727 I have.
The nss I have on hand is 7/8" deep from gasket face to plastic switch end. When not in reverse, the cam is 3/4" in from the trans case outer surface. when in reverse it is 13/16" in.
If it was me, I'd put the gear selector in drive and screw in the nss until the contacts open, then maybe a half turn more. Then move it into reverse and see if the contacts close. From the measurements on my trans, you only have 1/16" to play with. If you can't get the contacts to open, I have heard there are two different length nss switches, or perhaps the plastic surface of the cam is that badly worn?

[DAYLEY/CHALLENGER]

Well..........rather than messing with all the fluid and crawling aroung under the car in and out.........I took the bulb out of the backup socket.           

[Skunkworks Challenger]

dodj, thanks for the measurements and suggestions--very informative.  Because I'm pressed for time at the moment I removed my bulb (like Dayley/Challenger).  That puts the light out when going forward but now I have to replace it to back up then remove it again to go forward---very inconvenient!   Just kidding!  My 727 is a 69 model and does not have the plastic cam, just stamped steel.  I have a 71 model 727 that has a plastic cam.  When I get some time I will try the plastic cam in my car.  According to what I've seen they should use the same switch and should be interchangeable between transmissions.  Thanks for your help.  When I get it resolved I'll post my methods.  I'm heading to Victoria, BC this Thursday, July 21st, to a Regional WPC meet and car show. This will be the car's first time out of town and in public. Too bad I'll have to back up in the dark!  PK

[dodj]

My 727 is a 69 model and does not have the plastic cam, just stamped steel.  I have a 71 model 727 that has a plastic cam. 

Maybe Tactransman will chime in but is it possible the '69 used to have platic on it and has come off? The cam on my '75 727 is steel with plastic on it to isolate the start relayground (centre contact) when out of park or neutral.