NSS & VSS questions

[LockDoc]

Hi all,

Back to work on the '67 Panel with the LS1/4l60e. From what I can gather from posts on here, even though I am using a factory NSS switch on the tilt column I will still need to connect the trans NSS wire somewhere, I just can't figure out where. I saw a schematic in one of the threads where one poster built a circuit from Radio shack parts to connect the wire to and that all it does is increase the RPM by about 75 RPM when shifted into gear. I think another poster connected his to ground and the engine just idled 75 RPM higher all the time. Any other thoughts on this???

On the VSS, I am going to use a GPS speedometer and wondering if I can just de-pin the VSS wire and remove it in the tune.... I can't seem to get the VSS part through my thick skull.

Thanks,
LockDoc

[BR3W CITY]

VSS needs to be hooked up...its the NSS that can be ditched. The VSS is how the trans knows how fast its spinning (even if you aren't using it for Speedo). I'm running a Com-driven speedo (Scanguage) fwiw.

The NSS can be tuned out, which people tell you not to do for safety...but I'm in the "Bcuz Racetruk" group who doesn't really care. If you run a beefy cam, you'll end up idling higher anyway, enough so that that 75rpm won't matter one hair. Go big enough, and your idle window will be larger than that...so it REALLY won't matter.

Where the NSS is nice; if you have a manual car, or an auto that can't catch its idle when the convertor loads up. IMO if the car is NEEDING the nss to not stall, then there are deficiencies in its tune.

[LockDoc]

Originally Posted by BR3W CITY

VSS needs to be hooked up...its the NSS that can be ditched. The VSS is how the trans knows how fast its spinning (even if you aren't using it for Speedo). I'm running a Com-driven speedo (Scanguage) fwiw.

The NSS can be tuned out, which people tell you not to do for safety...but I'm in the "Bcuz Racetruk" group who doesn't really care. If you run a beefy cam, you'll end up idling higher anyway, enough so that that 75rpm won't matter one hair. Go big enough, and your idle window will be larger than that...so it REALLY won't matter.

Where the NSS is nice; if you have a manual car, or an auto that can't catch its idle when the convertor loads up. IMO if the car is NEEDING the nss to not stall, then there are deficiencies in its tune.

Since I'm using the stock Chevy truck NSS I should be OK on the safety end of it.

If I don't have an electronic speedo where do I connect the VSS signal wire?

LockDoc

[dayj1]

Originally Posted by LockDoc

Since I'm using the stock Chevy truck NSS I should be OK on the safety end of it.

If I don't have an electronic speedo where do I connect the VSS signal wire?

LockDoc

The VSS input wire goes from the trans to the PCM. You don't have to connect the VSS output from the PCM to anything if your speedo doesn't need it.

[LockDoc]

Originally Posted by dayj1

The VSS input wire goes from the trans to the PCM. You don't have to connect the VSS output from the PCM to anything if your speedo doesn't need it.

OK, Thanks guys. I appreciate the info.... Back to work for me..

LockDoc

[ls1nova71]

Originally Posted by LockDoc

Since I'm using the stock Chevy truck NSS

I thought you had an F body LS1? What harness/PCM and tune are you using? F bodys don't have a transmission mounted NSS. They only have one wire in the harness that needs to be grounded in park and neutral.

As a footnote, I would ALWAYS use a NSS. Those people who say "I'm the only one who will drive it, and I will always make sure its in park" are in my opinion not too safety conscious. It's called a "safety" switch for a reason. Just last weekend I watched a guy at a car show try to get his BBC powered Anglia to start, and when it did, it took off and hit a curb and a 65 Chevelle. Also, there was a guy lying on the ground afterward, but I'm not sure if it hit him or he tripped trying to get out of the way, but that could have ended really bad. A simple switch could have saved a lot of trouble, just sayin'.......

[solidaxel]

Originally Posted by ls1nova71

i thought you had an f body ls1? What harness/pcm and tune are you using? F bodys don't have a transmission mounted nss. They only have one wire in the harness that needs to be grounded in park and neutral.

As a footnote, i would always use a nss. Those people who say "i'm the only one who will drive it, and i will always make sure its in park" are in my opinion not too safety conscious. It's called a "safety" switch for a reason. Just last weekend i watched a guy at a car show try to get his bbc powered anglia to start, and when it did, it took off and hit a curb and a 65 chevelle. Also, there was a guy lying on the ground afterward, but i'm not sure if it hit him or he tripped trying to get out of the way, but that could have ended really bad. A simple switch could have saved a lot of trouble, just sayin'.......

x 2 !!

[LockDoc]

Originally Posted by ls1nova71

I thought you had an F body LS1? What harness/PCM and tune are you using? F bodys don't have a transmission mounted NSS. They only have one wire in the harness that needs to be grounded in park and neutral.

As a footnote, I would ALWAYS use a NSS. Those people who say "I'm the only one who will drive it, and I will always make sure its in park" are in my opinion not too safety conscious. It's called a "safety" switch for a reason. Just last weekend I watched a guy at a car show try to get his BBC powered Anglia to start, and when it did, it took off and hit a curb and a 65 Chevelle. Also, there was a guy lying on the ground afterward, but I'm not sure if it hit him or he tripped trying to get out of the way, but that could have ended really bad. A simple switch could have saved a lot of trouble, just sayin'.......

It is a '98 F Body engine but it has an '01 PCM and harness. It does have one NSS wire but I figured since I was going to use the early column mounted NSS system that I wouldn't need it. If need be I think I could put a micro switch on the shift linkage temporarily to ground it in park so it will start.

As far as tune, the PCM has been tuned for the mods to the engine and for standalone operation.

LockDoc

[ls1nova71]

Originally Posted by LockDoc

It is a '98 F Body engine but it has an '01 PCM and harness. It does have one NSS wire but I figured since I was going to use the early column mounted NSS system that I wouldn't need it. If need be I think I could put a micro switch on the shift linkage temporarily to ground it in park so it will start.

As far as tune, the PCM has been tuned for the mods to the engine and for standalone operation.

LockDoc

I think I may have confused you a little bit. You can just use the neutral safety switch on your column and hook up the original purple wire that went to your old starter directly up to the new starter. The PCM uses the NSS to know when the engine is shifted from park or neutral to slightly bump the idle. It isn't completely necessary, but if you can hook it up, I would. If you ever need to do a crank relearn, it has to be hooked up so the PCM knows the transmission is in park. As for hooking it up in the harness, it depends on what harness and what tune you are using. An F body harness and tune will use the single wire grounded in park and neutral, where as the truck harness has several wires that go from the trans mounted switch to the PCM. The tunes are different between the two. Also, if you got the transmission with your engine, the shift shaft on a car trans isn't long enough to add a truck NSS to it.