VSS Speed Sensors

[EagleMark]

My son is going to buy a inline VSS next payday for $75. What are you using for a VSS sensor? It's going in a 16197427 $OE TBI conversion on his IH. So no VSS at all...

[gregs78cam]

I tried an inline one, but it put out 8 pulse per Speedo Cable revolution, which is way different from 40 pulse per drivshaft revolution. It was off by a factor of 10+. I was doing 55-60 and it showed 5. I have one from a manaul trans S10.
http://www.gearhead-efi.com/Fuel-Injection/attachment.php?attachmentid=1819&d=1330825388

But I may grab one like this next time I go to P&S.
http://www.gearhead-efi.com/Fuel-Injection/attachment.php?attachmentid=1820&d=1330825388

both should work fine.

[EagleMark]

That second one looks very mountable!

80 pulse should only be 2x? You got 10+? Which made me think that if you use a 40 pulse from Jaqs that run does that include ALL differat size gears on speedo drives? How?

There is no access in trans like pdf attached shows, so it's either in speedo line or a ring like shown in pdf or Greg has for sale!

[FSJ Guy]

I used the same one that I used for the 7747 computer. 2PRS, IIRC. From Jags That Rug. JTR. For the 16197427 PCM, I selected the checkbox for "VSS not from DRAC.

I'm not controlling the transmission so I think that's why it works for me.

[EagleMark]

The wiring diagram for 4L80E shows VSS going straight to PCM with no VSSB/DRAC used in 4l60e. But there are many VSS options to change things under 4L80E but my $OE is a manual bin so I checked VSS not from DRAC, but I don't know if any of the VSS paremeter changes will work with manual?

[gregs78cam]

So if you have 3.08 gears and 27" tall tires (which is close to normal for 2WD cars), Then your driveshaft theoretically should spin 2536 Revs/Mile.
OK, we know the cables were normally calibrated to spin 1000revs per mile.

That comes out to somewhere between a 2:1 and 3:1 ratio, which follows the available gears for speedo correction.

The PCM wants to see 40 pulses for every driveshaft revolution. 2436 X 40 = 101438 Total pulses per mile.
So when we divide the pulses that we need per mile by the available cable rotations, you would need to have a 101ppRev sender for the cable mounted solution.

I tried the #54MG (http://www.transmissioncenter.org/speedometer_gear_housing.htm), and like I said.......not even close.
Here is the math for my truck.....
3.73, 35" (nominal) tires.......2149 Driveshaft Revolutions per mile. I have 2speed multipliers on the Speedo output, and it is close, (shows 55ish @60). So it is close to the 1000 per mile, lets call it 900.

PCM wants to see 40 X 2149 = 85960 pulses.
8pprev sender on cable gets me 8 X 900 = 7200.
Just like I said a little over 10X error. OK 11.934.

[Six_Shooter]

4L80E with the '7060 uses a DRAC, also all wiring diagrams I have seen for the '7427 use a DRAC, regardless of transmission.

[gregs78cam]

The wiring diagram for 4L80E shows VSS going straight to PCM with no VSSB/DRAC

Don't forget, 4L80e has two sensors, Input Speed sensor does infact go directly to PCM, the diagram I looked at for my Camaro showed VSSB/DRAC on Output Speed sensor.
http://www.gearhead-efi.com/Fuel-Injection/attachment.php?attachmentid=316&d=1321243211

[EagleMark]

So if you have 3.08 gears and 27" tall tires (which is close to normal for 2WD cars), Then your driveshaft theoretically should spin 2536 Revs/Mile.
OK, we know the cables were normally calibrated to spin 1000revs per mile.

That comes out to somewhere between a 2:1 and 3:1 ratio, which follows the available gears for speedo correction.

The PCM wants to see 40 pulses for every driveshaft revolution. 2436 X 40 = 101438 Total pulses per mile.
So when we divide the pulses that we need per mile by the available cable rotations, you would need to have a 101ppRev sender for the cable mounted solution.

I tried the #54MG (http://www.transmissioncenter.org/speedometer_gear_housing.htm), and like I said.......not even close.
Here is the math for my truck.....
3.73, 35" (nominal) tires.......2149 Driveshaft Revolutions per mile. I have 2speed multipliers on the Speedo output, and it is close, (shows 55ish @60). So it is close to the 1000 per mile, lets call it 900.

PCM wants to see 40 X 2149 = 85960 pulses.
8pprev sender on cable gets me 8 X 900 = 7200.
Just like I said a little over 10X error. OK 11.934.Can't you do anything without math? :laugh:


4L80E with the '7060 uses a DRAC, also all wiring diagrams I have seen for the '7427 use a DRAC, regardless of transmission.Well here's 16196395 and A10 goes to VSS but not a very good diagram.
http://www.gearhead-efi.com/Fuel-Injection/attachment.php?attachmentid=512&d=1322084443

And here's 16197427 with VSSB and 4L80E going to PCM hi and lo so maybe it's 4x4?

http://www.gearhead-efi.com/Fuel-Injection/attachment.php?attachmentid=314&d=1321243200

and here's a 16197427 VSS going into VSSB but does not say trans?

http://www.gearhead-efi.com/Fuel-Injection/attachment.php?attachmentid=316&d=1321243211

Now Greg says 4l80E has 2 speed sensors.. so I can't do math and still have no idea what to do about a speed sensor?

So that 40 tooth ring is looking better all the time...

[gregs78cam]

Can't you do anything without math? http://www.gearhead-efi.com/Fuel-Injection/images/smilies/laughing2.gif

Math is everywhere, man!


.. so I can't do math and still have no idea what to do about a speed sensor?


:laugh::laugh:

If you look at your second pic you see it says input speed sensor, the 4L80E has this to calculate Torque converter and clutch slip. It also has an output sensor for Vehicle speed. A 4WD will just have the VSS mounted in the Transfer Case instead of the non-existent tail housing.

[EagleMark]

If you look at your second pic you see it says input speed sensor, the 4L80E has this to calculate Torque converter and clutch slip. It also has an output sensor for Vehicle speed. A 4WD will just have the VSS mounted in the Transfer Case instead of the non-existent tail housing.Ok but in $OE it has a 4L80E Paremeter named "4wd Low Reduction Ratio" ?


Math is everywhere, man!
But I get a headache doing VE...

I haven't even looked to see if his speedo comes off his transfer case, but if it did this would be a 1 to 1 in high gear and I could put a 40 ppm in there.

Since it's a manual bin I'm wondering if these "4l80E VSS paremeters" are even going to work?

Since it's a manual how accurate does VSS have to be for the PCM to funtuion properly for engine? I know when these paremeters were off in my 4l60E it effected shifting, but engine ran fine...

[JeepsAndGuns]

I used the same one that I used for the 7747 computer. 2PRS, IIRC. From Jags That Rug. JTR. For the 16197427 PCM, I selected the checkbox for "VSS not from DRAC.

I'm not controlling the transmission so I think that's why it works for me.

I'm running the exact same one. It didnt work when I swapped in the 7427 untill I se the "input not from DRAC" Then it works like it should, and even reads correctly.
And I am running a $0E manual trans bin and had to change no other VSS or trans parameters.

[Six_Shooter]

Can't you do anything without math? :laugh:

Well here's 16196395 and A10 goes to VSS but not a very good diagram.
http://www.gearhead-efi.com/Fuel-Injection/attachment.php?attachmentid=512&d=1322084443


That's a pretty poor diagram, and just shows a connection to some non existant (in the diagram) VSS sensor, that could mean a DRAC, or directly to a sensor, it's really quite vauge and wouldn't base any thoughts ablout 4L80E not using a DRAC on that single diagram.


And here's 16197427 with VSSB and 4L80E going to PCM hi and lo so maybe it's 4x4?

http://www.gearhead-efi.com/Fuel-Injection/attachment.php?attachmentid=314&d=1321243200


Near the bottom at pins F12 and F13, it shows an input from the DRAC (VSSB), and these are known to be correct vehicle speed input pins.

Trans input speed is just that, input speed at the trans input shaft, not output shaft. The "hi" and "lo" in this case are refernces to electrical properties, the "lo" is essentially a ground, and the "hi" is the actually changing signal from the sensor that the ECM uses to watch trans input speed.

[quote]and here's a 16197427 VSS going into VSSB but does not say trans?

http://www.gearhead-efi.com/Fuel-Injection/attachment.php?attachmentid=316&d=1321243211


Huh? I see mention of both location on transmission and showing connection directly to the DRAC.

[93V8S10]

Well here's 16196395 and A10 goes to VSS but not a very good diagram.
http://www.gearhead-efi.com/Fuel-Injection/attachment.php?attachmentid=512&d=1322084443



Sorry, but this is not for a 6395 PCM. Look at the pin #'s.

[EagleMark]

Thanks 93V8S10! I'll remove that from the PCM information thread and try and figure what it is for?

[Nasty-Z]

Mark , That looks like a '7747 or the like .

FWIW , I haven't used a DRAC with the '7427's I have running , one is with a manual and one is a 700R4 , both have 2000PPM sensors inputed @ F13 and have no problems .

No electronic transmissions yet but one is on the horizon .

TOM

[Six_Shooter]

The electronic trans required the 40 PPR signal through the DRAC on pin F12.

[EagleMark]

Mark , That looks like a '7747 or the like .

TOMI think I got it in the wrong thread and it's a 16136965 91- 93 Caprice, LB4, L03 & L05 Eng. $62 wiring diagram...

Well no E trans ever planed for this, seems like guys are getting away with 2ppm but it's supposed to be 40ppm both are about same price but we have proof 2ppm works with bit set to VSS not from DRAC so think that's the beat bet?

[JeepsAndGuns]

we have proof 2ppm works with bit set to VSS not from DRAC so think that's the beat bet?

Looks like it. Mine works like a champ!

[gregs78cam]

Well, I got the 40tooth ring mounted to the T-case front output, fabbed a sensor mount, got it wired up, and it works great. I now just need to do the Tire/gear calculation to set the correct jumpers in the DRAC.

[Mastiff]

So can someone summarize for those of us who are a little slow? I want something that can maintain my existing cable for the speedo, plus output the right signal for the ECM. With the EBL it looks like I can adjust the pulses-per-mile between about 10 and 2000.

[EagleMark]

1227747 ECM right? Jaqs that run 2 ppm inline VSS sensor.

Your working on your Blazer right? If so you could look into a 1987 to 1991 Blazer, Suburban dash board which would have the VSS in behind the speedo. I've never tried this but they are same body style and dash looks the same as does most everything else. Someone may have already done it and you could check at CK5.org

[Mastiff]

One of the ones on this page?

http://www.jagsthatrun.com/Pages/SpeedSensors_Speedometer.html
(http://www.jagsthatrun.com/Pages/SpeedSensors_Speedometer.html)
Straight to the ECM, or do I still need some huge board to stick someplace?


1227747 ECM right? Jaqs that run 2 ppm inline VSS sensor.

Your working on your Blazer right? If so you could look into a 1987 to 1991 Blazer, Suburban dash board which would have the VSS in behind the speedo. I've never tried this but they are same body style and dash looks the same as does most everything else. Someone may have already done it and you could check at CK5.org

[dyeager535]

A bit late to this ballgame, but are you using stock gauges?

If so, can you work a stock 40 tooth reluctor into your setup? ('90-91 205 or 241, or at least tailhousing and reluctor ring?)

I felt I wasted a bunch of time/effort wiring VSS up in my truck with a cable speedometer, only to later on decide that the mechanical speedometer was more hassle than it was worth, and ended up going with the '90-91 electric speedometer, and related DRAC.

DRAC is far simpler to account for tire size/gear ratio changes, and has a variety of outputs to satisfy everything such as ECM, cruise, ABS, speedometer, etc. Obviously it is personal preference (cost/time vs. perceived benefit), but as I've grown more comfortable with the electronics, I'm more inclined to eliminate mechanical components for electronic.

[EagleMark]

He has a divorced 205 transfer case, but it's in good shape right now. But we will look for one for parts for future build.

Right now it looks like one is going in speedo line, or a 40 tooth on drive shaft of transfer case that Greg built? Actually this thing may be running this week without VSS till his next payday. So I may try to figure out how to run without VSS, drive tune, install VSS and compare differences in tune and drivability. Like I did on a 1227747 ECM conversion on a Scout II. I had it done and drove for a year without. Installed a VSS and drivability and idle etc... was improved! That is why I do not want to go without...

[dyeager535]

I remember some discussion of VSS necessity on the '7747 on CK5 some time back, and most without VSS were adamant that the '7747 just didn't need it. Until recently, I had no experience on the '7747 to comment. Now I do. From what I found on my Dad's setup (mild 454 build w/'7747) if something else is wrong (such as his IAC adjustment) the problem is compounded when VSS isn't present. His truck would stall nearly every time the clutch was depressed when coming to a stop. Hook up VSS, and while the IAC problem didn't go away, the truck no longer stalled. Obviously fixing the IAC is the solution, BUT when something does go wrong, there is no failsafe if everything isn't in place.

I understand the DRAC isn't for every application, but I highly recommend using it for the '73-87(91) series trucks if at all possible. There are enough of the '90-91 variants out there that the parts required aren't too pricey. 205's are a bit more difficult, but the parts can be had. I believe someone even did some work to a 241 reluctor to get it to fit on the 205. I wouldn't be surprised if some of the S10 t-case setups wouldn't also be potential donors.

[Scorp1us]

Is it possible to tell the PCM to expect a 4 pulse per rev input?