Throttle Pot

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VW Drive By Wire Pedal

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2003 VW Polo Throttle Pedal
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VW Throttle Pedal socket detail, what kind of plug matches?
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Inside a different VW Throttle Pedal, photo by Peter Gabrielsson

I got a 2003 Polo pedal from http://www.vwspares.co.nz/ for $150+GST. This fits better than the Zilla Hall Effect Pedal because the pedal arm is biased is to the right of the mounting which suits my car. It's a purely resistive pedal which suits my Simovert.

Edward discovered the equivalent circuit:

vw-pedal-equivalent-circuit.gif

  • R0 = 885
  • Rvp = 430
  • Rp = 715
  • Rvn = 55

I need to find a matching plug for the socket.

Channel A
Pin Volts
0v 5v m* *up down Delta
3 2 4 0.75 4.61 3.86
2 3 4 4.29 0.42 -3.86
4 2 3 2.54 4.6 2.06
2 4 3 2.49 0.44 -2.06
3 4 2 0.73 2.56 1.83
4 3 2 4.33 2.5 -1.83
Channel B
5 1 6 0.37 2.3 1.93
1 5 6 4.66 2.74 -1.93
5 6 1 0.51 2.05 1.55
6 5 1 4.53 2.98 -1.55
6 1 5 2.1 2.76 0.66
1 6 5 2.94 2.26 -0.67

I connected pin 3 to throttle ground, pin 2 to throttle 5v and pin 4 to the throttle input. This has worked extremely well in practice.

Measuring resistance between pins will give you a headache:

Pedal Up
Pin 1 2 3 4 5 6
1 x nc nc nc 1k2 2k
2 nc x 924 1k6 nc nc
3 nc 924 x 941 nc nc
4 nc 1k6 940 x nc nc
5 1k2 nc nc nc x 938
6 2k nc nc nc 940 x
Pedal Down
Pin 1 2 3 4 5 6
1 x nc nc nc 1k2 1k6
2 nc x 924 918 nc nc
3 nc 924 x 1k6 nc nc
4 nc 918 1k6 x nc nc
5 1k2 nc nc nc x 1k4
6 1k6 nc nc nc 1k4 x

Metric Mind's Pot

Metric Mind supplied a throttle pot, it looks like it's designed to sit on the side of a throttle body, I'll have to build a box to allow pulling it with a cable attached to the stock pedal.

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Throttle Pot supplied by Metric Mind
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Throttle Pot supplied by Metric Mind
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Wiring diagram for throttle pot supplied by Metric Mind

Hall Effect Pedal

This is the pedal that is optionally used on the Zilla. It is similar to the CTS 703 series pedal. See the zilla instructions.

Hairball Cable Pin Function
HEPI 1 Red 1 Power 1: 5v
Signal GND Black 2 Ground 1
HEPI 3 Green 3 Output 1: 1.6-4.8v
HEPI 4 White 4 Power 2: 5v
Chassis GND Blue 5 Ground 2
Chassis GND Bare Shield Wire Shield
HEPI 6 Orange 6 Output 2: 0.78-4.3v

At first sight it looks like it will work with the Simovert but unfortunately it requires more current than the Simovert will provide. The Simovert's 5v throttle supply drops to 3.2v with the pedal connected, which isn't enough to make the pedal work. It does work if you provide extra current, but the quality of the output is dependent on the quality of the input. I'm trying to improve on an already very reliable solution and I don't think the pedal + power supply will do the job. I also saw oscillations in the throttle input reported by the Simovert when I connected my bench supply to provide the extra current.

Converting a Hall Effect Pedal to 0-5k pot

Ian Hooper presents a circuit for reading one channel of a hall effect pot and driving a 5k two wire input. I don't need to to do this, but a variation could be used to read both channels of my pedal.

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