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VSS analog to PWM

DannyboyDS

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Ok so im converting to manual in my VS, I have a remapped ECU, but of course as eveeryone knows I miss out on the Vehicle Speed Sender, as the standard VS auto ECU uses Pulse Width Modulation (PWM) and the T5 I am using uses an oldschool analog signal, like high or low voltage.

So after considering all of the possibilities, such as.

1. Locate and use the correct ECU (To expensive and ahrd to track down)
2. An off the shelf converter (Could only find them in 8 pulse, I need a 40 pulse)
3. go without (Is problematic
4. changing over to a completly different ECU (Can be expensive and allot of mucking around that can result in everything not working)

So in the end ive decided on this as my project.

The picture below is a little rough and ready but hey, I did my best.



Basically the shaft of the old VSS goes through a bearing (for support) and into a plastic hobby box (Trying to reduce the amount of magnetic metal as not to affect the PWM generator.

the PWM generator has to be placed correclt alignment and distance from the reluctor ring are crucial, I have the figures somewhere, otherwise, back to google I will go :p

finally it also comes down to the gearing, need to get 40 pulses per driveshaft revelution for it to work straight off, otherwise a speedo corrector kit will be needed.

Anyone got any thoughts? any info? anyone allready done it? or is anyone good enough with circuits to make a PWM generator that increases pulses dependant on input voltage?

Better yet anyone seen a 40 pulse PWM generator on the net for sale, they basically replace the old VSS, plug right in, as the cogs turn it creates a PWM signal.
 

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DannyboyDS

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I think I found an off the shelf item that does this. With the amount of people doing manual conversions and using the auto ECU, I thought there would have been more interest.
 

delcowizzid

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i think the jaycar speedo corrector may be able to do it or there is another unit that can do it just noone has tested them and proved it works yet :D i can get a link for the one to turn sine wave in to square wave out or vice versa if you need it
 

DannyboyDS

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That would be great thanks Delco, I have scoured the net and have found what I hope is an off the shelf VSS, that will go directly into a T5 without any modifications, and emit a pulse wave for the AUTO ECU, so I might be in luck anyway.

I just don't know why it isn't talked about more, I mean arn't allot of people having conversion issues, or are they just lucky enough to have an ECU that suits?
 

Chirpstr

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I thought the auto VS ecu has the manual speed sensor reading in it already? Only the VS ecu though.
 

delcowizzid

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only certian VS auto ecu's have the nessacary internal componants
 

DannyboyDS

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well i've allready bought a VSS, hmm maybe i'll buy both :p
 

delcowizzid

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just be aware this all could be a waste of money if the ecu is seeing auto speed pulses cause its programmed with specific gear ratios in the tune and it may pack a mental at you due to the manual having different gear ratios
 

ejukated

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just be aware this all could be a waste of money if the ecu is seeing auto speed pulses cause its programmed with specific gear ratios in the tune and it may pack a mental at you due to the manual having different gear ratios

it will be fine, if the pulse is actually suitable to be read through the auto vss pin. Thats just the same config as a getrag gearbox
 
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