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Thread: VSS Speed Sensors

  1. #16
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    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
    1994 3500 Dually , 502 , 264HR , Edelbrock MPFI
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    1993 K-3500 "Ex-diesel" 454/4L80E
    1992 454SS "Eh Stock" W/Wynjammer
    1992 S-10 434 SBC/Tremec
    1984 S-10 , SAS, 454/700R4/205 , D44/14BFF
    1980 Z-28 454/700R4
    1977 Olds 98 Regency 403/700R4

  2. #17
    Super Moderator Six_Shooter's Avatar
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    The electronic trans required the 40 PPR signal through the DRAC on pin F12.
    The man who says something is impossible, is usually interrupted by the man doing it.

  3. #18
    EFI GearHead ! EagleMark's Avatar
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    Quote Originally Posted by Nasty-Z View Post
    Mark , That looks like a '7747 or the like .

    TOM
    I 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?

    1990 Chevy Suburban 5.7L Auto ECM 1227747 $42!
    1998 Chevy Silverado 5.7L Vortec 0411 Swap to RoadRunner!
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  4. #19
    Fuel Injected! JeepsAndGuns's Avatar
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    Quote Originally Posted by EagleMark View Post
    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!
    79 Jeep Cherokee, AMC 401, T-18 manual trans, hydroboost, 16197427 MPFI system---the toy

    93 Jeep YJ Wrangler, 4.0L, 99+ intake, SS header, dynomax exhaust, 5 speed, 8.8 rear, WJ front brakes, hydroboost, P-pump conversion, 2.5in OME lift, 31x10.50's---the daily driver

    99 Jeep WJ Grand Cherokee limited, 4.0L, auto, 2wd, leather and power everything, 99% stock---the long distance highway ride.

  5. #20
    Fuel Injected! gregs78cam's Avatar
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    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.
    1978 Camaro Type LT, 383, Dual TBI, '7427, 4L80E
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    1974 Chevy/GMC Truck, '90 TBI 350, '7427, TH350, NP203, 6" lift, 35s

  6. #21
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    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.

  7. #22
    EFI GearHead ! EagleMark's Avatar
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    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

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

  8. #23
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    One of the ones on this page?

    http://www.jagsthatrun.com/Pages/SpeedSensors_Speedometer.html

    Straight to the ECM, or do I still need some huge board to stick someplace?

    Quote Originally Posted by EagleMark View Post
    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

  9. #24
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    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.

  10. #25
    EFI GearHead ! EagleMark's Avatar
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    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...

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

  11. #26
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    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.

  12. #27
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    Is it possible to tell the PCM to expect a 4 pulse per rev input?

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