ranger6

Does the speedometer have to operate in order for the transmission to shift in "Drive?" It shift manually from 1st to 2nd but no further. I drive it seems to be starting in a higher gear.

performabuilt2

yes it does some will and some wont but most of the time the computer will need a VSS signal to operrate correctly

FLT

iTrader: (1)

It sounds like your transmission is in a limp mode condition due to the speedometer not functioning properly. The reason that it seems to be starting in a higher gear in drive is because it is actually starting out in third gear. Get the speedometer problem fixed before you drive any further or do any damage. Vince

performabuilt2

since we are sounding technical here. some models and years can opereate without the VSS by using the MAP sensor which would function as a modulator with low vacumm you would have high TV therefore cuasing a downshift or to hold the gear longer before an upshift with high vacumm the pcm would know from the vacumm signal that it needs to upshift. however in your situation and your system you need the VSS to operate the transmission properly. Kinda thought I answered the question before

bad69bird

I've been lurking here for years. I like the technical discussions. Superficial answer do not help me get a better understanding of my car.

What vehicles use the MAP sensor to determine when it is time to upshift? I think that is cool. Can I put one one on my car?

FLT

iTrader: (1)

I pretty much answered his question and also explained with his vehicle what was going on. Not sure as to where you were going with MAF theory. Also I added as to why it felt like it was starting out in a higher gear when in the drive range. Nice attempt to bash me here. I think after reading your post maybe you should take a course in punctuation and spelling. Good night Robert

FLT

iTrader: (1)

I would have to say that almost every vehicle uses them these days along with other electronics's. However it is not the only sensor on the vehicle to help determine how the trans performs. Vince

performabuilt2

Hi G what I am saying is that the PCM on some vehicles can use the MAP as a backup to the VSS in case of the primary signal the VSS being lost as far as exact models not really sure but in my training I have learned about the strategy instead of going to a full limp mode it will still operate just not at optimal performance untill a repair could be made SES light would still come on and all that but you just wouldnt have one gear in case you were on a trip or in the middle of nowhere. i HOPE you learned something from this G

performabuilt2

good night vince sleep well.