VSS on SAS

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Hamps

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I reached out to a staff member and was informed to try this part of the forums. I will reach out to Howell today and run it past them. Here is the link to the VSS I purchased and I believe this will be the direction to go because it produces the needed pulse signal 2000 PPM.
https://howellefi.com/product/tpi-tbi-vehicle-speed-sensor/
I attached the manual for the VSS look under step 2 for early TBI. That is where it says to install the signal wire to the ECM and my wiring diagram matches what everything is saying.
The only thing I have left to complete my SAS is to fix the speedometer. It is a 1989 2wd 700r4 that I went nuts and turned it into a 4wd 4spd. I purchased a VSS from Howell because it was one that I could find that would provide the needed 2000 Pulse Per Mile.
The purple and yellow twisted pair wires that use a magneto pickup from the factory 2wd 700r4 are still there. Purple is high speed from what I can tell and yellow is low speed. These wires go directly to the cluster and supply signal/pickup from what I can tell and back feed to the ECM through a brown wire with red stripe on A10. The VSS switch I bought from Howell is the 2000 pulse per mile and their instructions state to put the red wire "from the VSS" mounted on the speedo gear in the transfer case directly to the ECM A10 location then the black wire directly to ground. I have tried literally everything I can think of and I can still not get my speedometer to operate. I have not tried twisting the yellow and purple wire together and running the wire to the ECM from the VSS.
The speedometer worked well before and tach read 2400 RPM at 65MPH in drive. With the new combination I will have 35 inch tires and tach should read 2500 RPM at 65 MPH so I do not think there will be an issue with the DRAC once I get it to work. If anyone has any input I could really use the help in getting the speedometer issue sorted. I used page 984 on the manuals offered here https://www.gmt400.com/threads/88-95-service-manuals.43575/
Here is my pile for reference https://www.gmt400.com/threads/pig-pens-89-gmc-2wd-sas-auto-to-sm465.52511/
thanks for any help on this issue.
 

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PlayingWithTBI

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This may be a stupid question but, is the reluctor gear for the VSS installed on the output shaft? A lot of transmission builders don't install it.
 

stutaeng

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I'll have read through your build thread, but what transfer case did you use?

Isn't the VSS in the TC of the 4x4 models?
 

Hamps

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I used a cable drive Np208 transfer case. Yes before the purple and yellow wire were connected to the 2wd 700r4 magneto.
Purple and yellow wire are no longer connected they are hanging for now. Spot A10 at ECM is where directions state to plug the new VSS signal wire into the ECM then ground to chassis. I've tried this and multiple other scenarios. I have found everything in the diagrams and it all is jiving I'm just not completing something but I do feel I'm in the ballpark. Thanks for the look see. I am basically out of ideas. The one thing that is weird to me is the process. The VSS appears to go to the cluster first then to the ECM. Different that what I expected to see.
 

Hamps

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I am going to apply the trouble tree to what steps I have taken and see if there is any useful information or some other anomaly that shows itself. I am running 8C-16 pg983.
 

Hamps

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Ran the trouble tree and came up with the same. I wire a proper resistor in and tried to provide signal from the VSS but didn't come up with anything. Dakota Digital it is I guess. Not a bad thing but didn't want to spend the $800 on that. Unless anyone else has anything they may want to add. Appreciate it.
 

Traveling man

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I reached out to a staff member and was informed to try this part of the forums. I will reach out to Howell today and run it past them. Here is the link to the VSS I purchased and I believe this will be the direction to go because it produces the needed pulse signal 2000 PPM.
https://howellefi.com/product/tpi-tbi-vehicle-speed-sensor/
I attached the manual for the VSS look under step 2 for early TBI. That is where it says to install the signal wire to the ECM and my wiring diagram matches what everything is saying.
The only thing I have left to complete my SAS is to fix the speedometer. It is a 1989 2wd 700r4 that I went nuts and turned it into a 4wd 4spd. I purchased a VSS from Howell because it was one that I could find that would provide the needed 2000 Pulse Per Mile.
The purple and yellow twisted pair wires that use a magneto pickup from the factory 2wd 700r4 are still there. Purple is high speed from what I can tell and yellow is low speed. These wires go directly to the cluster and supply signal/pickup from what I can tell and back feed to the ECM through a brown wire with red stripe on A10. The VSS switch I bought from Howell is the 2000 pulse per mile and their instructions state to put the red wire "from the VSS" mounted on the speedo gear in the transfer case directly to the ECM A10 location then the black wire directly to ground. I have tried literally everything I can think of and I can still not get my speedometer to operate. I have not tried twisting the yellow and purple wire together and running the wire to the ECM from the VSS.
The speedometer worked well before and tach read 2400 RPM at 65MPH in drive. With the new combination I will have 35 inch tires and tach should read 2500 RPM at 65 MPH so I do not think there will be an issue with the DRAC once I get it to work. If anyone has any input I could really use the help in getting the speedometer issue sorted. I used page 984 on the manuals offered here https://www.gmt400.com/threads/88-95-service-manuals.43575/
Here is my pile for reference https://www.gmt400.com/threads/pig-pens-89-gmc-2wd-sas-auto-to-sm465.52511/
thanks for any help on this issue.
Hay man" I've got a 93 4×4, I bought it it had a 6in suspension 3 inch body lift and 35 inch tires with 348 gear. It couldn't get put of it's own way, 2200 rpm at 70mph on hwy was good for gas mileage unless you hit an incline and you couldn't keep it up to speed, and it would overheat pulling an empty 6 by 10 trailer up the hills where I live, so I researched proper gear ratio for 35" tires, most everyone said 456. But one fellow said, 456 put you back at normal but the tires are heavier so you don't want normal + 488 is only 200 more RPM, now that I've done it I wish I would have went with the 456, because the 37 in Tires I'd planned on which would have been perfect for these 488's are way too extreme for Factory front differential, the plan now is to use the donor LS swap truck 3/4-ton front IFS, I don't really use the truck hard enough to justify a 2005 Ford SAS swap or 78 Ford Dana 60, but we'll see how it goes plans change, ANYWAY...when I swapped in the 488's it wouldn't shift right along with the speedometer being way off, I spent A LOT of time researching, what I came up with was having to order from overseas because there is no Radio Shack anymore these five polls dip switches that are soldered into the vss circuit board in the little White plastic box behind the glove box, you have to take your tire size gear ratio ect ect, and calculate it into a binary code, up down up down up up down, it was tough for my poor little old brain, I also bought a unit from f.a.s.t to fine tune it to be absolute exact. Just a few wires and you turn a little bitty screw while going down the road with your GPS. Probably got notes that I made somewhere? Anyway, I'm not using any of this anymore, I LS swapped. I sold off my original motor and transmission but I kept the vss board that I altered and the fast unit, it's set for 488's & 35" tires as stated, all you have to do is figure in your tire size gear ratio flip the ten little mini dip switches up and down for the code that it comes up with, dial in the f a s t to make it absolutely perfect. I would sell this outfit but I just ran across this post I don't know what I want for it, I would have to look up what I've got into it, not counting the month or so it took to figure it out and shipping of course, mostly just cost, but I really don't know how to go about shipping and receiving payment.
 

Hamps

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I appreciate the offer. The factor is that I can’t get the proper pulse signal to the gauge cluster. The factory magneto utilizes a field to supply a high/low speed then to cluster then to ecm per the wiring diagram. 2000 pulse per mile style.
2wd 1:1 drive on the 700r4 28” tires at 65mph churned out 2500rpm.
The sm465 in 4th 1:1 35’s with 4.10s is right at 2550-2600rpm. DRAC isn’t the issue gears are pretty close. I’m not getting any input with design and Dakota I will be able to direct feed the pulse signal to it. Easy button would to be run the np241 driver drop out of a 92 I have with VSS but hell I couldn’t find a ford HP axle. I don’t need a 60 because I’m not running over 35 inch tires. I still want to use my garage.
 
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