VSS to speedometer wiring ?

[yossarian19]

My Omega Kustoms gauge instructions say to wire the VSS directly to the speedometer and then calibrate the speedo.
Only, I can't wire them straight to the speedo - they need to reach the computer, after all.
My thinking is that I can splice in another twisted pair of wires from the vss to the gauges & that will be fine, as the computer is looking for an amount of voltage (not amperage) which won't be changed by feeding the speedo too.
Am I right, here? Or am I going to screw the pooch by trying this?

[Big Port Jimmy 6]

Use the speedo output from the pcm? Jay

[ls1nova71]

Autometer says to tap directly off the VSS too, but when I tried it, it skewed the signal going to the PCM and caused erratic transmission shifting problems. Hooking it up to the speedometer output from the PCM fixed it.

[lutronjim]

Trying to get parts list for ls to 70 c10. Read about lots of problems on forum with Cable x. Found a Dekota Digital ECD-100 that seems to solve several mentioned problems.

They want to hook right to VSS also. Is the signal out of the PCM the same as from the VSS?

Thanks

[BR3W CITY]

Yes, and also NO...it could be

Depending on what trans and what VSS type it uses, it can have different signal. This would be a good time for ClineBarger to come on this thread and tell me what I'm getting wrong here, since I know I'm gonna have something sidways;

Something like a T56 or 4l60e uses something like a 40 pulse A/C sine wave. (out)
iirc the LS1 f-body speedometer uses a 4000 pulse, square wave signal (out).
Dakota digital aftermarket stuff uses 8000 pulse. (this is common for aftermarket gauges)
DBW trucks can function off of the 8k, but actually want a 120k to get things like the Cruise control to work. It needs the additional resolution/polling to work properly.

In any effect, I'd just hook to the ECM output, since you can go back in HP Tuners and just change the vss signal options. Its from like 0-2579643 or some huge number that should be well more than you'd ever need.

Find out what signal its looking for tho, it might help.

[dayj1]

Originally Posted by BR3W CITY

Yes, and also NO...it could be

Depending on what trans and what VSS type it uses, it can have different signal. This would be a good time for ClineBarger to come on this thread and tell me what I'm getting wrong here, since I know I'm gonna have something sidways;

Something like a T56 or 4l60e uses something like a 40 pulse A/C sine wave. (out)
iirc the LS1 f-body speedometer uses a 4000 pulse, square wave signal (out).
Dakota digital aftermarket stuff uses 8000 pulse. (this is common for aftermarket gauges)
DBW trucks can function off of the 8k, but actually want a 120k to get things like the Cruise control to work. It needs the additional resolution/polling to work properly.

In any effect, I'd just hook to the ECM output, since you can go back in HP Tuners and just change the vss signal options. Its from like 0-2579643 or some huge number that should be well more than you'd ever need.

Find out what signal its looking for tho, it might help.

You didn't get sideways. The only problem that I see is that the T56 is 17 pulses driveshaft revolution instead of the 40 used by the 4L60/80.

I'd also add that most of the aftermarket gauges that I've encountered will handle the A/C VSS or the square wave with any frequency between 2K and 128K.

[BR3W CITY]

Good lookin Dayj

Since we're talking about it, I went and dug up a few more.
The T5 is a 4k ppm
FWD ls based cars with 4t65 and similar have a 24k ppm

More random info that may or may not be useful lol

[lutronjim]

Y'all guys are way over my head. I am a newbie to this.

I assume DBW trucks means drive by wire. I see y'all use FWD ls cars - front wheel drive?

I am trying to come up with parts necessary to put a 'CPSLC94L65E connect and cruise' in my 70 c10 step side. It has LC9 engine and electric OD 4L65E tranny. Current 305 has over 300 and is pissing oil.

The speedo was next on my list. Want to add vintage air with their belt system. Have a handle on mounts and fuel system.

Anyway I have the L1 guide and I see pin C1 55 VSS output - I would assume this would go to speedo. I also see C2 35 for tach output.

It just dawned on me --- electric gear selection. I currently have 3 on column but have auto column to put in.

Hope y'all wont mind putting up with me.

Thanks for info.

[dayj1]

Originally Posted by lutronjim

Y'all guys are way over my head. I am a newbie to this.

I assume DBW trucks means drive by wire. I see y'all use FWD ls cars - front wheel drive?

I am trying to come up with parts necessary to put a 'CPSLC94L65E connect and cruise' in my 70 c10 step side. It has LC9 engine and electric OD 4L65E tranny. Current 305 has over 300 and is pissing oil.

The speedo was next on my list. Want to add vintage air with their belt system. Have a handle on mounts and fuel system.

Anyway I have the L1 guide and I see pin C1 55 VSS output - I would assume this would go to speedo. I also see C2 35 for tach output.

It just dawned on me --- electric gear selection. I currently have 3 on column but have auto column to put in.

Hope y'all wont mind putting up with me.

Thanks for info.

CPSLC94L65E comes with the 19256514 engine controller package.

The instructions for 19256514 are available online here:

http://www.crateenginedepot.com/pdfs...controller.pdf

On page 5 of the above manual, VSS output is shown to be the brown wire at position "D" on the bulkhead connector. That's the one you want to hook to your speedometer. It's worth mentioning that the "fine print" says the signal is not scaled. In other words, it's probably a square wave representation of the sine wave created by the VSS sensor in the transmission. What that means to you is that you'll want a speedometer that is capable of "auto-scaling" or, in other words, is capable of syncing with a range of VSS signals. I've used Classic Instruments and Autometer speedometers in the past and they were auto-scaling. Just check before buying one.

[BR3W CITY]

Originally Posted by lutronjim

I assume DBW trucks means drive by wire. I see y'all use FWD ls cars - front wheel drive?



Anyway I have the L1 guide and I see pin C1 55 VSS output - I would assume this would go to speedo. I also see C2 35 for tach output.

It just dawned on me --- electric gear selection. I currently have 3 on column but have auto column to put in.
\.

Yep, we mean drive by wire. The FWD thing was just brought up as sort of an "aside" if you will. There are some cars like the cop impala's and such, that came with a front wheel drive engine that falls into the LS family, but is a bast@rd in the way it fits in. Its called the LS4, and has a different bellhousing pattern, uses a different type of 4t-series transmission, and doesn't really interchange with our stuff.

Did you have a question about the gear selection? Are you wanting to still have a colum-shift auto, or switch to a floor shift unit or aftermarket?

[lutronjim]

Thanks for the come back.

I would like to have the column shift. Does the 4L65E have a mechanical linkage and provide the PCM with were the selector is located? In my LS1 manual it shows a selector switch like would be on the column but only park and neutral had wires going to PCM.

I may be going outside this thread. If I am please redirect me.

Thanks

[yossarian19]

Originally Posted by lutronjim

Thanks for the come back.

I would like to have the column shift. Does the 4L65E have a mechanical linkage and provide the PCM with were the selector is located? In my LS1 manual it shows a selector switch like would be on the column but only park and neutral had wires going to PCM.

I may be going outside this thread. If I am please redirect me.

Thanks

the 4L60E, which I think is going to be the same, has a mechanical selector. On trucks, the selector shaft has a gear position sensor (neutral safety switch, amongst other functions) mounted to that shaft. On car transmissions, it doesn't - the switch is mounted to the shifter.
The engine controller wants to know when it's in park or neutral so it can adjust the idle speed. From talking to Current Performance and stalking the internet forums, it doesnt' seem to be very important. You definitely need a vehicle speed sensor signal. The gear you are in? Not as important to keep the engine running properly.
You can run any GM transmission as a column shift. Lokar will have the parts you need.

[lutronjim]

Thanks

[BR3W CITY]

The truck DOES actually know what gear its in, thats provided through controlling the trans solenoids. The gear indicator thats on the shaft is ONLY for the HUD readout, and serves no additional function besides NSS. The NSS functions can be hooked up to an aftermarket shifter, or modified from pretty much anything that has an NSS.

I don't use one, and the ONLY downside is that with the addition of things like Hydroboost or high-draw accessories, the lack of park/neutral idle control is occasionally annoying, but by no means a dealbreaker. The heavy-cammed motors sometimes need a tad higher idle under the load of the trans, because the lope can occasionally stall them if the idle is too low and the driver isn't maintaining it/bumping it with the pedal. This means that when you pop into neutral, you may idle a touch high (kinda like it was still warming up).

[lutronjim]

If I get the 'connect and cruise', could the selector shaft gear position sensor from a truck be added to its tranny. Sounds like that would be much better that trying to provide some switch/s to provide info from linkage.

I'm a little confused. If the neutral and park are the only thing supplied to the PCM, how would you tell the tranny to stay in first or second?

Thanks

[BR3W CITY]

That lever you pull that put the truck into park helps

When you put the truck into 1, your physically pulling the selector shaft into 1st. When its in D, it uses the normal valve pattern 1-4/lockup. The nuetral and park are things sent to the pcm from THAT harness... NOT from both the trans harnesses. The big round plug with 11-14 pins contains the shift solenoid wiring and all that.

All the NSS is, is a switch that makes or breaks a connection to the circuit telling the pcm whether or not its in park. It should really be called a PSS (park safety sensor), since the engine knows its in neutral when you physically shift it there (and the load comes off the engine). On an aftermarket floor shifter, this is simply a contact switch mounted to make contact when the shifter is in P. Most will come with this, but its extremely easy to add to any custom shifter as well.

Column shifters are a tad different, but they can still be done. You don't physically have to mount the NSS @ the transmission.

[lutronjim]

Thanks

[Hart_Rod]

Lots of good information here, as usual!! As far as the transmissions go, the A4's (4 speed auto's) can be manually selected to each gear position (PRND321).

The A6's (6 speed autos -6 L80/6L90s) can't be mechanically shifted to a specific forward gear (1-6). Those transmissions can only be "mechanically" shifted to the following positions - PRNDM/S.

The "D" position, is programmed to automatically upshift and downshift the transmisson through all 6 forward gears.

The "M" position (usually on trucks or SUVS) allows the driver to manually select the highest gear that the transmission will "automatically" shift into. It also activates the tap up tap down (TUTD) feature on the shifter handle.

The "M" position, or "SPORT" position on Corvettes/Camaros, changes the transmission "tune" or programming to a more aggressive shift pattern that "tightens" up the shifting of the transmission. It also activiates a cars TUTD switch or paddle shifters if installed.

Some more cool features about the A6 is that it contains all of the information for gear position, neutral safety, tranny temp, etc that can be displayed via a BUS system if your gauges (SpeedHut/Dakota Digital/Speartech...) has the capability. I'll try to post a picture of some of the programmable parts of an A6 from HPTuners. The programming for an A6 is actually more complicated than the LS engine is...

R