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Dumb reverse lights.... #336839
06/03/09 02:53 AM
06/03/09 02:53 AM
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hi
sharpie Offline OP
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Okay, so weird problem - my reverse lights are on in reverse AND in drive, 2, and 1. Neutral and park do not have them on as usual. I know this must be an issue with the Back Up Light Switch Circuit, but I have no idea how to fix it. Is this common? Do I have a short, or do I just need to change something? Any help is appreciated!

Re: Dumb reverse lights.... [Re: sharpie] #336840
06/03/09 07:30 AM
06/03/09 07:30 AM
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On the open road
Hrtbkr Offline
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I just worked through this problem. If you have (I"m not sure of the exact year for the change) a '70 or older transmission, the switch in the side is only for neutral safety. The reverse lights are switched either at the floor or column shifter. The trans switch for the older style had a single connector. You can install a newer three prong switch, but then you get the symptoms you describe.
To fix this, you need two friends like I have. Darryl GAVE me the correct valve body (the cam on the shifter rod activates the safety and back up lights plus you get part throttle kick down), and you need Kenny to install it. Automatics are a complete mystery to me , but Kenny swapped VB's last night like it was nothing...


While outside on the turnpike They got this new hit tune Where thrills become as cheap as gas And gas as cheap as thrills
Re: Dumb reverse lights.... [Re: Hrtbkr] #336841
06/03/09 08:38 AM
06/03/09 08:38 AM
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Florida
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scratchnfotraction Offline
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yes if it on the colum at the floor you need the one wire nss

like said the rooster comb is diff for the 3 prong nss

you can move the rev light switch for some adjustment on the colum some..that might help

the trans you took out would have the nss and correct vb,but I know you said it gone

so its just a matter of the right nss maybe

find out if its got the rev light switch on the colum


Re: Dumb reverse lights.... [Re: scratchnfotraction] #336842
06/03/09 10:36 AM
06/03/09 10:36 AM
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Posts: 5,037
hi
sharpie Offline OP
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Well, my trans is from a 76 truck and my car's a 71, so I think it's supposed to have the 3-wire NSS (same plug came with my wiring harness originally). I don't know if that helps or not.

Re: Dumb reverse lights.... [Re: sharpie] #336843
06/03/09 11:32 AM
06/03/09 11:32 AM
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68HemiB Offline
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Indeed, the rooster comb inside can vary, but I am not sure that this should come into play, given the years of the parts you used. IIRC, '68 was the last year of the single pin NSS and reverse lights from elsewhere.

It would be very useful diagnostic information if you could establish that the switch and comb are or are not truly the source of your problem. Doing so might avert the need to start digging into the internals of the transmission needlessly.

I would suggest that you disconnect the harness plug from the switch, and use an ohm meter to establish if the outer two pins in fact have continuity in reverse/drive/2/1 and no continuity in park and neutral (matching your symptoms).

a. If this is the case, it's bad news and time to dig further into the switch integrity and switch/comb interaction.

b. However, if the outer pins behave as they should (continuity in reverse, and no other gear), you can breathe a sigh of relief and continue your search external to the transmission itself.


Down to just a blue car now.
Re: Dumb reverse lights.... [Re: sharpie] #336844
06/03/09 12:35 PM
06/03/09 12:35 PM
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Texas
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6packattk Offline
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I ran into this problem on my bee a few years ago and finally figured out my three prong wiring harness plug was so heat hardened it was not plugging in correctly,got one from mopar junk yard,same problem,no one made new ones at the time.Wired each wire to prongs seperately using typical wire crimp connector(tube type)crimped just enough on prong end to make tight like won`t never fall off.Works great,I was getting ready for texas car inspection.Back up lights are checked.Would of liked to have factory end but was not to bee

Re: Dumb reverse lights.... [Re: 6packattk] #336845
06/03/09 01:01 PM
06/03/09 01:01 PM
Joined: Sep 2007
Posts: 5,037
hi
sharpie Offline OP
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Does it matter which way the plug goes on? It can only go on two ways, but if upside down won't work, I should know.

Re: Dumb reverse lights.... [Re: sharpie] #336846
06/03/09 01:07 PM
06/03/09 01:07 PM
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Posts: 32,882
Grand Prairie,Texas
stumpy Offline
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It will work either way. The two outer terminals are just in and out not directional.

Re: Dumb reverse lights.... [Re: sharpie] #336847
06/03/09 03:37 PM
06/03/09 03:37 PM
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Rio Linda, CA
John_Kunkel Offline
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The only way to know if the transmission is configured correctly for the 3-prong switch is to remove the switch and determine what type of internal lever (roostercomb) is installed. If the lever has two metal contacts it won't operate the 3-prong switch' if it has the correct lever with a plastic shoe the ploastic end might be broken off.

Below is a pic of the different internal levers and the switches that they operate.

5270469-NSSwitches.jpg (63 downloads)
Re: Dumb reverse lights.... [Re: John_Kunkel] #336848
06/03/09 03:55 PM
06/03/09 03:55 PM
Joined: Sep 2007
Posts: 5,037
hi
sharpie Offline OP
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Wow John, that's a great picture. I do know that I have the middle lever, with the fox-ears on the switch-side of the lever. I can't tell whether the middle switch is a three-prong, but the one I have in there looks exactly like this:


Last edited by sharpie; 06/03/09 03:56 PM.
Re: Dumb reverse lights.... [Re: sharpie] #336849
06/03/09 04:55 PM
06/03/09 04:55 PM
Joined: Jan 2003
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Grand Prairie,Texas
stumpy Offline
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If you have the middle lever you need a single terminal switch. For backup lights you need the third lever and three prong switch. You can see how the lever slides along the switch to make it work in different positions. The middle one only works the switch with the two points in park and neutral for starting.

Re: Dumb reverse lights.... [Re: stumpy] #336850
06/03/09 05:33 PM
06/03/09 05:33 PM
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sharpie Offline OP
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So how would I go about resolving the issue?

Re: Dumb reverse lights.... [Re: sharpie] #336851
06/03/09 05:48 PM
06/03/09 05:48 PM
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Florida
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scratchnfotraction Offline
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pull the vb and install the new 3 prong nss rooster comb in you vb

I have the right rooster comb if ya need it

the vb is for parts so I dont need it

its yours if ya want it




Re: Dumb reverse lights.... [Re: sharpie] #336852
06/03/09 06:35 PM
06/03/09 06:35 PM
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Rio Linda, CA
John_Kunkel Offline
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Only the '69 and '70 roostercomb (on the left below) can be used to convert a '68 and earlier valve body, the '71 and later is different.

Re: Dumb reverse lights.... [Re: John_Kunkel] #336853
06/03/09 09:27 PM
06/03/09 09:27 PM
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scratchnfotraction Offline
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maybe not

I thought it was a 76 truck tranny


Last edited by scratchnfotraction; 06/03/09 09:31 PM.
Re: Dumb reverse lights.... [Re: scratchnfotraction] #336854
06/03/09 10:34 PM
06/03/09 10:34 PM
Joined: Jan 2003
Posts: 32,882
Grand Prairie,Texas
stumpy Offline
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Seems to me if it was a 76 trans it wouldn't have the two prong lever in it.

Re: Dumb reverse lights.... [Re: stumpy] #336855
06/03/09 10:39 PM
06/03/09 10:39 PM
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SoCal
68HemiB Offline
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Referring back to my earlier post...


...it's easier to yank the valve body of a transmission than to hold the probes of an ohm meter up to two pins on the NSS?


Down to just a blue car now.
Re: Dumb reverse lights.... [Re: 68HemiB] #336856
06/04/09 01:29 AM
06/04/09 01:29 AM
Joined: Sep 2007
Posts: 5,037
hi
sharpie Offline OP
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I am thinking it's pretty solid that I have the wrong NSS switch in there, because I've seen the inside of the transmission (and thus the shift lever) when I was reconditioning it. Since the only real difference between 69+ NSS is 1- or 3-pin and thus the part that touches the switch (rooster comb seems to be the same), I really think it's the switch. How would I go about re-routing the reverse light circuit? It seems easier to get a 1-pin NSS switch and reroute the reverse light circuit than to replace the shift lever and valve body.

Re: Dumb reverse lights.... [Re: sharpie] #336857
06/04/09 08:09 AM
06/04/09 08:09 AM
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Florida
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scratchnfotraction Offline
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IMO the rooster comb is easier to do than rewire the rev light circit

the detent ball is the hardest thing to deal with changing it

its 12 or so bolt that hold the vb in place

and you can put a new throttle valve shaft seal in there while your at it


Re: Dumb reverse lights.... [Re: sharpie] #336858
06/04/09 10:56 AM
06/04/09 10:56 AM
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SoCal
68HemiB Offline
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Quote:

I am thinking it's pretty solid that I have the wrong NSS switch in there, because I've seen the inside of the transmission (and thus the shift lever) when I was reconditioning it. Since the only real difference between 69+ NSS is 1- or 3-pin and thus the part that touches the switch (rooster comb seems to be the same), I really think it's the switch. How would I go about re-routing the reverse light circuit? It seems easier to get a 1-pin NSS switch and reroute the reverse light circuit than to replace the shift lever and valve body.




Some members (myself included) are a bit confused how such a late transmission could have an early roostercomb. You know more about the ancestry of the transmission, have seen the innards for yourself, and seem to buy onto the "wrong comb" theory, even without testing with an ohm meter. So be it.

Assuming that your problem is a comb/NSS mismatch (as I said - a leap for some of us), the task at hand is to match the NSS and car wiring to the comb, or the comb to the NSS and car wiring. I think I join the majority here in thinking that the latter is the easier path. Your idea to search out a single pin switch leaves you needing a whole 'nother set-up to get your reverse lights working. In a column-shifted automatic, this was done with a switch near the bottom of the steering column. And it is not just a switch and some wires - there needs to be a matching pin-like thing on the shifter linkage to engage the switch. The sarcastic side of me wants to recommend you seek out a "1968 Demon" to gather your needed parts...

I would urge you to confirm your problem first. THEN, if it really is a comb/switch mismatch, reconsider going the comb changing route.

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