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Thread: VSS Speed Sensors

  1. #1
    RIP EagleMark's Avatar
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    VSS Speed Sensors

    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...

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    Fuel Injected! gregs78cam's Avatar
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    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.


    But I may grab one like this next time I go to P&S.


    both should work fine.
    Attached Images Attached Images
    1978 Camaro Type LT, 383, Dual TBI, '7427, 4L80E
    1981 Camaro Z-28 Clone, T-Tops, 350/TH350
    1981 Camaro Berlinetta, V-6, 3spd
    1974 Chevy/GMC Truck, '90 TBI 350, '7427, TH350, NP203, 6" lift, 35s

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    RIP EagleMark's Avatar
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    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!
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    1990 Chevy Suburban 5.7L Auto ECM 1227747 $42!
    1998 Chevy Silverado 5.7L Vortec 0411 Swap to RoadRunner!
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  4. #4
    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.
    Familiar with 1227747 and 16197427 PCMs

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    RIP EagleMark's Avatar
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    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?

    1990 Chevy Suburban 5.7L Auto ECM 1227747 $42!
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    Fuel Injected! gregs78cam's Avatar
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    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/sp...ar_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.
    Last edited by gregs78cam; 03-04-2012 at 07:38 AM.
    1978 Camaro Type LT, 383, Dual TBI, '7427, 4L80E
    1981 Camaro Z-28 Clone, T-Tops, 350/TH350
    1981 Camaro Berlinetta, V-6, 3spd
    1974 Chevy/GMC Truck, '90 TBI 350, '7427, TH350, NP203, 6" lift, 35s

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    Super Moderator Six_Shooter's Avatar
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    4L80E with the '7060 uses a DRAC, also all wiring diagrams I have seen for the '7427 use a DRAC, regardless of transmission.
    The man who says something is impossible, is usually interrupted by the man doing it.

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    Fuel Injected! gregs78cam's Avatar
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    Quote Originally Posted by EagleMark View Post
    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.
    Last edited by gregs78cam; 03-04-2012 at 08:29 AM.
    1978 Camaro Type LT, 383, Dual TBI, '7427, 4L80E
    1981 Camaro Z-28 Clone, T-Tops, 350/TH350
    1981 Camaro Berlinetta, V-6, 3spd
    1974 Chevy/GMC Truck, '90 TBI 350, '7427, TH350, NP203, 6" lift, 35s

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    RIP EagleMark's Avatar
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    Quote Originally Posted by gregs78cam View Post
    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/sp...ar_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?

    Quote Originally Posted by Six_Shooter View Post
    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.


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



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



    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...

    1990 Chevy Suburban 5.7L Auto ECM 1227747 $42!
    1998 Chevy Silverado 5.7L Vortec 0411 Swap to RoadRunner!
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  10. #10
    Fuel Injected! gregs78cam's Avatar
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    Quote Originally Posted by EagleMark View Post
    Can't you do anything without math?
    Math is everywhere, man!

    Quote Originally Posted by EagleMark View Post
    .. so I can't do math and still have no idea what to do about a speed sensor?


    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.
    Last edited by gregs78cam; 03-04-2012 at 09:46 AM.
    1978 Camaro Type LT, 383, Dual TBI, '7427, 4L80E
    1981 Camaro Z-28 Clone, T-Tops, 350/TH350
    1981 Camaro Berlinetta, V-6, 3spd
    1974 Chevy/GMC Truck, '90 TBI 350, '7427, TH350, NP203, 6" lift, 35s

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    RIP EagleMark's Avatar
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    Quote Originally Posted by gregs78cam View Post
    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" ?

    Quote Originally Posted by gregs78cam View Post
    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...

    1990 Chevy Suburban 5.7L Auto ECM 1227747 $42!
    1998 Chevy Silverado 5.7L Vortec 0411 Swap to RoadRunner!
    -= =-

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    Fuel Injected! JeepsAndGuns's Avatar
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    Quote Originally Posted by FSJ Guy View Post
    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.
    79 Jeep Cherokee, AMC 401, T-18 manual trans, hydroboost, 16197427 MPFI system---the toy

    93 Jeep YJ Wrangler, 4.0L, 5 speed, 8.8 rear, homebrew hub conversion and big brakes, hydroboost, 2.5in OME lift, 31x10.50's---the daily driver

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  13. #13
    Super Moderator Six_Shooter's Avatar
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    Quote Originally Posted by EagleMark View Post
    Can't you do anything without math?

    Well here's 16196395 and A10 goes to VSS but not a very good diagram.
    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?

    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?




    Huh? I see mention of both location on transmission and showing connection directly to the DRAC.
    The man who says something is impossible, is usually interrupted by the man doing it.

  14. #14
    Vintage Methane Ejector
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    Quote Originally Posted by EagleMark View Post
    Well here's 16196395 and A10 goes to VSS but not a very good diagram.


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

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

    1990 Chevy Suburban 5.7L Auto ECM 1227747 $42!
    1998 Chevy Silverado 5.7L Vortec 0411 Swap to RoadRunner!
    -= =-

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