Galant throttle position sensor

[AutoHelp]

I have a 1994 Mitsubishi Galant ES SOHC, which is having running difficulties under power (usually stalls). I suspect the throttle position sensor (TPS) may be at fault. I measured the resistances between the TPS connector pins with the following results. Note that I am using an analog ohmmeter, so my measurements are approximate (i.e. don't get too hung up on the absolute values of the measurements). The pins on the TPS are marked +, S, O, -. The number values shown below are with the throttle fully closed. The description line below each number value indicates how that resistance changes as the throttle position is changed from fully closed to fully open.

- + 4.8 Kohms
same value as move throttle from open to closed position
- S 46 ohms
jumps to open circuit shortly after throttle moves from closed
position
- O 540 ohms
increases smoothly to 4 Kohms as change throttle position from
closed to open position
S O 750 ohms
jumps to open circuit shortly after throttle moves from closed
position
S + 4.8 Kohms
jumps to open circuit shortly after throttle moves from closed
position
O + 4.3 Kohms
decreases smoothly to 0 as change throttle position from closed
to open position

Do these measurements indicate the TPS is good or bad? I did not expect a 4-pin device. I expected a three pin device with the center pin changing resistance smoothly from closed throttle to open throttle. What is the schematic of my TPS?

Thanks.

[gmech]

Originally Posted by AutoHelp

I have a 1994 Mitsubishi Galant ES SOHC, which is having running difficulties under power (usually stalls). I suspect the throttle position sensor (TPS) may be at fault. I measured the resistances between the TPS connector pins with the following results. Note that I am using an analog ohmmeter, so my measurements are approximate (i.e. don't get too hung up on the absolute values of the measurements). The pins on the TPS are marked +, S, O, -. The number values shown below are with the throttle fully closed. The description line below each number value indicates how that resistance changes as the throttle position is changed from fully closed to fully open.

- + 4.8 Kohms
same value as move throttle from open to closed position
- S 46 ohms
jumps to open circuit shortly after throttle moves from closed
position
- O 540 ohms
increases smoothly to 4 Kohms as change throttle position from
closed to open position
S O 750 ohms
jumps to open circuit shortly after throttle moves from closed
position
S + 4.8 Kohms
jumps to open circuit shortly after throttle moves from closed
position
O + 4.3 Kohms
decreases smoothly to 0 as change throttle position from closed
to open position

Do these measurements indicate the TPS is good or bad? I did not expect a 4-pin device. I expected a three pin device with the center pin changing resistance smoothly from closed throttle to open throttle. What is the schematic of my TPS?

Thanks.

AutoHelp, got this info straight from one of my repair manuals - hope it helps...

The Throttle Position (TP) sensor is a potentiometer that provides a signal to the PCM that is directly proportional to the throttle plate position. The TP sensor is mouinted on the side of the throttle body and is connected to the throttle plage shaft. The TP sensor monitors throttle plate movement and position and transmits an appropriate electrical signal to the PCM. These signals are used by the PCM to adjust the air/fuel mixture, spark timing and EGR operation according to engine load at idle, part throttle, or full throttle. The TP sensor is not adjustable.
The TP sensor receives a 5 volt reference signal a ground from the PCM. A return signal circuit is connected to a wiper that runs on a resistor internally on the sensor. The further the throttle is opened, the wiper moves along the resistor, at wide open throttle, the wiper essentially creates a loop between the reference signal and the signal return returning the full or nearly full 5 volt signal back to the PCM. At idle, the signal return should be approximately 0.9 volts.

TESTING
1. With the engine OFF and the ignition ON, check the voltage at the signal return circuit of the TP sensor by carefully backprobing the connector using a DVOM.
2. Voltage should be between 0.2 and 1.4 volts at idle.
3. Slowly move the throttle pulley to the Wide Open Throttle (WOT) position and watch the voltage on the DVOM. The voltage should slowly rise to slightly less than 4.8 volts at WOT.
4. If not voltage is present, check the wiring harness for supply voltage (5.0 volts) and ground (0.3 volts or less), by referring to your corresponding wiring guide. If supply voltage and ground are present, but no output voltage from TP, replace the TP sensor. If supply voltage and ground do not meet specifications, make necessary repairs to the wiring harness or PCM.

[bunalmis]

Where is the TP Sensor.

Are there any photo on the web?

[gmech]

Originally Posted by bunalmis

Where is the TP Sensor.

Are there any photo on the web?

check this out - http://files.automotiveforums.com/ga...php?photo=4254