3fe vss (1 Viewer)

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I recently installed a Dakota Digital cluster in my 73 with the add on GPS module. A couple years ago I converted my rig to 3FE and with that conversion I deleted the VSS function. I am happy to see the Dakota Digital module has vss to ecm output and I really would like to connect it to my ecm but am not sure what output of the three the gps offers is the right one for my ecm. Anyone done this?
 

tornadoalleycruiser

Erik TLCA #5303
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Watching, the gps module instructions are not exactly self explanatory
 

Engineer8000

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I read the brochure on the GPS unit. It outputs a sine wave or square wave Pulses Per Mile (PPM) signal. The 3fe ECM is looking for a reed switch opening and closing in proportion to vehicle speed so it can make it's own pulses. I am not sure any of the outputs from the DD GPS unit will work with the 3fe ECM.

The speedo I have here in the shop says 60 mph = 1025 rpm, so doing the math I get 6150 pulses per mile, with a six pulse/rev VSS. It's a 40 speedo btw.
 
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I thought it would be cool if it did use the DD GPS output. I don't know how much of a gain in performance if any at all, if it does read it.
 

Engineer8000

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Based on the info in the manual, the VSS must be used during warm up for something. Why would a cold engine running between 2000 and 5000 rpm need to know the truck speed, except when racing the engine? Maybe some sort of deceleration control for emissions like the old throttle positioner?


1655599573868.png


BTW, the pulses per mile above is based on the fj40 6 pulse VSS, the FJ62 has a 4 pulse VSS.

I have the disassembled code from the 3fe ecu, I should look at what the VSS is used for.
 
Joined
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I recently installed a Dakota Digital cluster in my 73 with the add on GPS module. A couple years ago I converted my rig to 3FE and with that conversion I deleted the VSS function. I am happy to see the Dakota Digital module has vss to ecm output and I really would like to connect it to my ecm but am not sure what output of the three the gps offers is the right one for my ecm. Anyone done this?
I installed the vss from the gps to the ecu the way the tech guys at DD suggested and it works well. I am still not convinced the vss is needed but the more data the ecu has the better.
 

tornadoalleycruiser

Erik TLCA #5303
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So u used an out on the gps module to vss ecu wire. I need to move mine from the main dakota unit to the gps unit and see if that helps. I sometimes get a situation where it dies when I come to a stop. Could also be tps setting. Thank you.
 
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So u used an out on the gps module to vss ecu wire. I need to move mine from the main dakota unit to the gps unit and see if that helps. I sometimes get a situation where it dies when I come to a stop. Could also be tps setting. Thank you.
Connect the vss(spd) ecu wire to the speed 1 position on the gps. Then set unit to 4 in the pulse set up in the speed settings and thats it. Extremely accurate speed and I really just like having the outside air temp and compass heading on the speedometer.
 

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