giddyup21

Check Engine Light on. diagnostic check returned Pedal Position Sensor - TPS-P0122 - A Circuit Low Input. Getting terrible acceleration and poor response to gas pedal, also uneasy idle. Wondering what voltages i should be getting on wires connected to TPS. Guy at autozone said it was probably a lose or corroded wire?thanks

EE_Chris

Put the meter ground on some conventional ground spot.

Using the red lead, probe each of the 3 wires (with the TPS connected - it has to recieve a reference voltage).

One wire is going to read +5v, one wire should read 0v; The third wire, at idle, should read .45-.49v. When you find the 3rd wire, assuming it reads .45v, rotate the TPS to make sure it doesn't drop out in voltage - should be a nice linear movement up to around 4.5v or so.

Since you didn't specify which car/year, I gave generic directions instead of wire colors.

giddyup21

99 Civic EX.. completely forgot that. Am i measuring the wires on the top of the throttle body or on the back of the throttle body? thanks

EE_Chris

Since the TPS has to rotate as you press the gas pedal, it resides on the same shaft that the throttle cable is hooked to. So more than likely, the back.

The top mounted sensor is the MAP.

giddyup21

also should the car be running or just the key turned on?

giddyup21

car idles at .52v but went very smoothly straight up to 4.71 volts... is the slight difference between .45 and .52 enough to set off the check engine light?

glosssilver

the car dont need to run just key on.... check the continuity between the signal wire and the ecu .... if u have a lose pin at the ecu or damaqe wire can cause resistance .... hint-- cause low reading to the ecu.

hope that help