Pulldown resistors for TPS MAP

[goflo at pacbell.net]

This is the most likely, and will give 0 to nearly 5V adj

        5V   ______
                   |
                   /  5K pot, linear taper 
                   \
                   /<------ Variable voltage to ECU input
                   \
                   /
                   |                   |
                   |
                 Ground

                          /*  less likely  */

5V pull-down  _____
voltage from       |                   
ECU                |
                   /  5K linear taper pot
                   \
                   /<---------/\/\/\-------- Ground
                   \            1K 
                   /            
                   |
                   |
               No connection
                 
This will give approx 1V to 5V adj. If you need less than 1V
( say .9V ) use a smaller current limiting resistor, but at 
least 500 ohms or so. This resistor prevents shorting the 5V 
input to ground at the high end of the pots travel ... If the 
ECU uses this scheme the current is probably internally limited
but we dont need to find out the hard way that it is'nt. It is
Monday, after all.

If this doesnt make sense describe the connections as fully as 
possible and we'll beat on it some more.

Regards, Jack


Bruce Plecan wrote:
> The ecm supplies a 5v signal to the TPS, and MAP.  The MAP is
> a strain guage type device with a couple transistors.  What is inside
> a TPS, I don't know.  The TPS needs to return a signal from .5v to
> 4.9v (.5 being idle). to the ecm.  The map at engine off is like
> 4.9, idle 2.v ish..
> Appreciate a hand

> >What signals and signal range do these inputs require? I don't
> >know diddley about these ECUs but am interested. Probably can
> >tell you how to fake em once I know what's required... Promise
> >not to buff anything.