Hi,

Polo 1993 1.0l CAT

There is an unusual(?) Idle Control Valve.

It uses a DC motor (not a stepper motor) and a pair of contacts.

It seems two of the pins are attached directly to the DC motor and two pins for the contacts.

I'm guessing the contacts are used to put the controller in to the start position, any one know if this is true?

Any idea how to drive one of these without killing the DC motor by driving it against an end stop?

This part is being fitted to a DIY project and I'd like to be able to control the valve from a micro or directly from passives. It wont be connected to the Bosch controller.

Thanks in advance,

Keith

The switch contacts are just for the throttle closed info, it switches a ground from pin 4 to pin 3 when the throttle is closed.

Here's the info on the motor control pin 3 & 4

Hi Nige8021,

Thanks for the very fast response....

Sorry, I'm being a bit slow on the uptake here...

So pins 3 and 4 are open circuit unless the throttle is closed?

Does that mean pins 1 and 2 are connected to the dc motor? Perhaps pin 1 to 0v and pin 2 pulsed either +15v or -15v with the speed of movement controlled by the pulse width?

15v seems unlikley but it does say 5V for the scope setting - I'm taking this to be 5v per division?

Looks like expensive software you are using there, AutoData?

Thanks again.

Edited 8 October, 201411 yr by kbs

Pins 1 & 2 are connected to the motor from the ECU pins 34 & 16 it's a pulsed Battery voltage hence it looks like 15v from the scope display (14.4v alternator voltage) I don't have the details of how the voltage is switched but I would guess it was just a pulse of +supply voltage and just swop polarity for directions? and as you said the speed controlled by the pulse width

Pins 3 & 4 are closed circuit with the throttle closed

Yes it is from Autodata 2 CD

Thanks again Nige,

Sorry to bug and send me away as soon as you have had enough.....

So, the contacts indicate fully closed and are used to inform the ECU of position so that the ECU doesnt drive the DC motor beyond the fully closed position?

I assume the fully open position is protected as the mech can roll off the end of the helix gear but due to a spring, can always close when motor rotated other way?

Last question on the IAC, in the following image, is it;

Pin a A = is Pin1

Pin a B = is Pin2

Pin a C = is Pin3

Pin a D = is Pin4

No visible numbers on these pins, "A" is the highest pin (closest to bonnent) when fitted. I do have a stub of the loom for this so if the pin info isn't available, do you know the wire colour for pin 1?

Many thanks - I'll keep looking for an old 'autodata' CD set, looks very useful.

Keith

Edited 9 October, 201411 yr by kbs

Hi Nige,

Very last enquiry for the electronics in the current project....

The TPS on this vehicle - is it two pots wired in reverse or power in and a signal voltage out?

At least the pins are numbered on this one! (ignore red numbers)

Thanks again for all your help,

Keith

Edited 9 October, 201411 yr by kbs

Pin 1 White/Black

Pin 2 White

Pin 3 Green/Red

Pin 4 Brown/Black

I would assume the throttle closed switch has more to do with cutting the injector signal when the throttle is closed when above a certain RPM as part of the fuel economy?

Never dismantled one so I can't comment on the internal protection

Here are some diagrams that might help in the first B147 is the TPS and the second shows the pins on the IAC

Hi Nige,

Thanks for all the excellent help and diagrams.

Perhaps feed beck from the TPS is used when driving the IAC to ensure it is not driven past the end of its range?

Must be something to stop it being driven into the stops?

Thanks again, plenty to be going on with - I'll get it moving off the car this weekend. The final aim is to have manual control of the valve from a 'mometary action' double pole change over switch (with protection against driving it into the stops!).

Keith