Member Since: 02 Aug 2022
Location: Llanfairpwll
Posts: 15
Resistance of Throttle pedal.
My saga with the throttle pedal continues. The circuit diagram of the throttle shows that the pedal should be two potentiometers with all connections brought out separately. If I measure mine I don't find that. One potentiometer as expected, but the other is a variable resistance one way and fixed the other. The second-hand spare I bought to replace it measures exactly the same. It is possible that I have been sold a dud so I wonder if anyone is able to either confirm exactly what is really in the throttle pedal or has a good spare kicking around that they can measure?
All the best
David
27th Mar 2024 10:25 am
Pete K
Member Since: 15 Jan 2016
Location: GL
Posts: 10367
They won’t be identical pots for safety reasons. They will have different charastics.
27th Mar 2024 12:53 pm
dpround
Member Since: 02 Aug 2022
Location: Llanfairpwll
Posts: 15
Sorry, I should have been clearer. The pedal from the car and the replacement bought from ebay are showing the same symptoms. On both pedals one of the "potentiometers" is not working as I would expect. This may show that both are fine, or both are broken... I was asking if anyone has a good one to use as a third opinion.
27th Mar 2024 1:02 pm
Jamiehol
Member Since: 13 Nov 2015
Location: Ipswich
Posts: 347
The two pots in Drive by Wire pedal often read in inverted manners so one goes as you think from say high to low resistance to get 0 to 100 percent throttle and the other will go low to high.
I don’t know if the D3 ones are the same or not
27th Mar 2024 1:07 pm
PROFSR G
Member Since: 06 Mar 2017
Location: Lost
Posts: 4658
Re: Resistance of Throttle pedal.
dpround wrote:
My saga with the throttle pedal continues. The circuit diagram of the throttle shows that the pedal should be two potentiometers with all connections brought out separately. If I measure mine I don't find that. One potentiometer as expected, but the other is a variable resistance one way and fixed the other. The second-hand spare I bought to replace it measures exactly the same. It is possible that I have been sold a dud so I wonder if anyone is able to either confirm exactly what is really in the throttle pedal or has a good spare kicking around that they can measure?
All the best
David
Do you have access to a diagnostic tool? If you do you can watch the potentiometers behaviour in "live values" as you press the throttle pedal. (Ign on engine off)
What you want to see is a continuous steady increase in voltage from the closed position to fully open and back again to closed. The range for sensor(1) is 0.75v to 4.0v, and for sensor (2) 0.25v to 2.0v. Sensor(1) is the "lead" sensor, and should be tracked by sensor(2) with it's voltage closing in on the values for sensor(1) as the pedal reaches full depression. (2.0v sensor2) and (4.0v sensor1) respectively.
ie Sensor 2 will always be behind sensor 1 (for safety considerations) within it's own voltage range until full throttle is achieved. Forget about resistance as this can provide misleading or erroneous results. The other important factor here is the battery and alternator voltages are within acceptable operating ranges.
If the voltage curves for either potentiometers are distorted, out of range, or otherwise corrupted the pedal sensor/throttle actuator needs replacement.
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