Bosch eGas wiring...

[2226cc]

I am looking for the pin-out information for the Bosch eGas electronic throttle body fitted to the 993/996.

The part number on the unit is "996 605 115 01". Bosch part number is "0 280 750 008". The plug is a 6-pin item. Here is a picture:

Also, is this connector available? From experience, Audi insist on supplying the wiring loom, but with the part number in hand for some other connector I was able to show them up and have them order the connector I needed. Can anyone hand me the part number for the connector on the wiring loom for this part?

[Loren]

Pin 1 - minus (-) motor throttle valve

Pin 4 - plus (+) motor throttle valve

Pin 2 - throttle valve ground

Pin 5 - signal throttle valve

Pin 3 - plus (+) 5 volts

Pin 6 - signal throttle valve

[2226cc]

That was fast! Thanks. :)

Are #1 and #4 constant 12V driven (battery connection)? Or is it a range indicating throttle opening?

Do you by any chance know if #3 (+5V) is constant or is that the control signal?

Just trying to figure out from the diagram which pins need to be driven with which signals in order to control the valve opening.

Thanks for the quick respsonse. :)

[Loren]

1 and 4 are inputs for the power to the throttle control positioner motor. This is what opens/closes the throttle butterfly for idle, and normal acceleration.

3 looks like it is a constant 5 volts.

To me 5 and 6 seem to be the sensing position signals and then 1 and 5 again to position the throttle butterfly.

[2226cc]

I assume then the motor control is 12V considering the tension it has to overcome to move the butterfly valve.

Is 5 an input or output?

[Loren]

All these connections go to the DME (Bosch Motronic). Sorry, I do not have a 7.2 (egas) version OBD II manual so I can't tell you what is in the DME for sure.

[2226cc]

Not a problem. With the info you gave me I can try and have a chat to a local technician at Audi/VW/Bosch and see what they have on file. The late-spec VW/Audi cars use the same thing, I think, although be it in different dimensions.

[2226cc]

Some extra info, from MoTeC. I'll read up on their M800 and M880 to see what Aux1 and Aux2 are setup in terms of signals. Looks like 5 & 6 are outputs from the throttle body. Control must then be by 0-12V on pin 4, or a pulse-width signal.

http://www.motec.com.au/drawings/x28.pdf

[0586slb]

The e-gas throttle bodies are a servo controlled motor operating at a PWM controlled (5V or 12V - I can't remember) to drive the motor with dual opposing feedback potentiometers.

The ECU provides a Pulsed Width Modulated 5V signal to drive the throttle. So if the throttle needs to open quickly, the pulse mark-to-space ratio will be large and the butterfly will move quickly. If the increment is small, very small pulses will be provided to make precise movements. The pulses are a positive or negative voltage - depending on which way the throttle butterfly has to move.

The potentiometers feedback to the ECU the exact position of the butterfly, so the ECU knows how many more pulses it needs to deliver to get the butterfly to where it wants it to be. (This is the principle behind servo control, without going into horrendous hysteresis and overshoot/backlash considerations...)

The potentiometers are duelled, one increases its output and the other reduces and each value is fed into a separate microcontroller inside the ECU. Each microcontroller compares the results with its companion, and if there is a discrepancy, the throttle is shutdown into the 'limp' position and the lamp lights on the dash. (System redundancy)

The throttle pedal again has two potentiometers opposing, and acts in the same way.

Edited March 27, 2005 by 0586slb

[2226cc]

Thanks. :)

I opened it up and the potentiometers are fairly run-of-the-mill setup (carbon tracks?). I'll pull the motor as well, just held in by 2 screws anyway. Will see what the part numbers are on it and what kind it is exactly.

Is that PWM constant, or is it only applied when the throttle needs to move? I ask because the motor fights against a fairly tight spring, so I assume it will be fed a constant signal to maintain position.

It was indicated earlier that the input to the motor is 12V.

Not being too familiar with servo or stepper motor control, may I just ask if by servo you also mean stepper motor? I will look up information on controlling servo motors, etc., online.

This throttle body is quite a simple thing in construction. :) I expecting to see loads of funky stuff in there under the cover.

I'll get hold of a use VW/Audi unit and experiment with that. Don't want to destroy the motor in here.

Now does anyone have the wiring information for the electronic pedal? Bosch item, 6-pin as well.

[0586slb]

Thanks. :)

Is that PWM constant, or is it only applied when the throttle needs to move? I ask because the motor fights against a fairly tight spring, so I assume it will be fed a constant signal to maintain position.

Not being too familiar with servo or stepper motor control, may I just ask if by servo you also mean stepper motor? I will look up information on controlling servo motors, etc., online.

<{POST_SNAPBACK}>

Yes, PWM is constant, if you turn the ignition on but don't start, you can hear the throttle 'whine' and it will change tone with the position of the gas pedal. The spring controls the throttle to the closed position in the event of a malfunction or disconnection of the drive.

No, a stepper motor starts from a predetermined position, then a number of steps will move it to another known position, (if this is interrupted, it has to motor back to its start position to know how far to step again) whereas the position of a servo motor is allways known because of the position feedback potentiometers. The stepper motor has a complex field/armature arrangement, so one impulse moves it, say, 5 degrees.

[2226cc]

Ah, ok.

I'm looking up servo motor control information now. Wide range of methods, some indicating 50% duty cycle to maintain position, and so on. Less than that, closes, more than that opens it.

I guess now I need a similar motor to play with.

[2226cc]

Me again. Anyone have the part number for the 6-pin connector on the wiring loom that fits this throttle body connector? Or a Bosch number?

To make it easier for me I might just get a VW/Audi throttle body for messing around with the PWM/PWPS and then swap the covers around in order to use a VW/Audi plug.

Thanks. :)