TPS Signal
Thread Starter
Joined: Apr 2008
Posts: 2,023
Total Cats: 19
From: Outside Portland Maine
My TPS isn't reading in MS. It reads with the stim just fine.
I checked the pin on the harness and it reads varying resistance depending on where I go with the accelerator, and it reads from the same pin as the stim but I can't seem to make megasquirt show this.
The resistance from the stim is between 7 and 600 ohms. The resistance from the TPS in the car is between 480 and 1690ohms (that's foot off to foot on the floor)
It's just not making sense to me.
I checked the pin on the harness and it reads varying resistance depending on where I go with the accelerator, and it reads from the same pin as the stim but I can't seem to make megasquirt show this.
The resistance from the stim is between 7 and 600 ohms. The resistance from the TPS in the car is between 480 and 1690ohms (that's foot off to foot on the floor)
It's just not making sense to me.
Joined: Sep 2005
Posts: 34,402
Total Cats: 7,523
From: Chicago. (The less-murder part.)
First, the TPS is not read by the MS as a variable resistance, it's read as a variable voltage. You put +5 on one side, ground the other, and you now have a voltage divider. As the wiper moves across the TPS resistor, the voltage at the wiper varies from 0 to 5v.
You did hook up +5Vref to pin 2K (light green / white) and you grounded pin 2D (black / blue), yes? Measure with a voltmeter between 2M (red / blue) and GND with the MS powered up and you should see the voltage vary from .5 to 4.5 (or so) as you depress the pedal.
You did hook up +5Vref to pin 2K (light green / white) and you grounded pin 2D (black / blue), yes? Measure with a voltmeter between 2M (red / blue) and GND with the MS powered up and you should see the voltage vary from .5 to 4.5 (or so) as you depress the pedal.
Thread Starter
Joined: Apr 2008
Posts: 2,023
Total Cats: 19
From: Outside Portland Maine
Thanks! Now if I can only figure out this fan thing by myself, I will have accomplished something without running to the forum.
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Zaphod
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