How does the glow plug module know what the rpms are for injector start valve?

[R.E.wing_fc3s]

this post got moved to the general section where it says to NOT post technical questions so im reposting it here

 Im transplanting an aaz(not sure which code) into a vanagon. It had a poorly installed aaz without the lda pump which the owner failed to check the oil often enough resulting in engine failure. We sourced a most most likely canadian aaz. Im trying to understand how the glow plug control module knows what the rpms are to then control the injection start positioner valve. It seems most engines and pumps that have this valve also have a couple sensors that this pump does not have. This pump only had the egr switch(deleted)  the fuel shutoff switch and the injection start positioner.

The harness from the pump to the main round connector is unchanged. on the chassis side it is cut.

ive read that voltage to this valve is cut above 2800rpm.

ive also read the full throttle basically cancels the effect of the valve.

ive read that the valve serves to retard timing. doesn't this counteract the manual cold start cable?

the reason i want the valve to work is because energized it makes the car run smoother at cold idle and seems to help the engine run smoother when cold. 

i dont have the glow plug control module yet to control the injector start positioner valve because i want to understand how the module knows when to switch the valve when theres no apparent rpm signal to the module with this pump.

or i could wire the valve to be energized all the time like it mentions in the "how to" for more power. but i really want to know 

[vanbcguy]

A picture of your pump would help. Some have a solenoid which keeps equal pressure on both sides of the timing piston when NOT powered. The cold start handle still can physically move the piston but there's no dynamic advance.

Most folks hook it up so it has 12V at all times. This causes the pump to function normally.

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