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Discussion Starter #1
how does the pcm knows it what gear you are,
exemple first low or no presure on S0
on S2 pressure is diferente depending on gear

do we have some switch in the tranny ???
or the pcm is brite enougn to know it what gear we are in looking in rpm versus speed ?
 

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That's a hella good question. Think I'll scour the FSM's for a bit.
 

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Vehicle speed is directly related to RPM. Vehicle speed = gearing X rpm

If you are going 20 mph at 6,000 RPM (fake numbers) it can be deduced you are in first gear

If you are going 20mph at 4,000 RPM (fake numbers again) it can be deduced you are in 2nd gear.

For each gear your mph will always be X at Y RPM.

This may or may not be how the PCM decides, but its more probably then having a 'current gear' signal going ot the PCM.
 

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That is exactly how it knows which gear you are in. Its kind of like the auto trannys for chrysler which has 2 speed sensors, an input and an output. The tcm on auto tranny's see's the difference in speeds between the two sensors to know which gear its in so it knows when to shift. On our manuals. It uses the engine rpm (since there is practically no slip on the clutch) as an input speed and there is an output speed sensor on the trans. Thats how it determines each gear.
 
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