Ok I know this topic has been covered a zillion times(yes I've searched) but I still need the forum's help. Car is a 1986 NA S4 and I need to know what is the ground wire for the tps. I am not getting a reading at all so I want to reground the sensor.

 

The ecu ground

 

Do you have proper reference voltage to sensor?

 

There are three wires running to the TPS. Green/Red should measure 1 volt w/key to on and engine fully warmed. BrownWhite wire (or just plain Brown) has 5 volts w/key to on. The Black or Black/Red wire is the ground and it comes from pin 2C of the ECU which also ties into pin 3A which ties into 2R and these latter two pins tie into the engine ground on top of the engine.

 

ok thank I just adjusted the tps and today is the first time the car has given me a reading in a year! I set it for 1k ohms when closed but WOT has no reading. Also when checking for volts does the tps have to be plugged in?

 

check the plug on the harness for voltage, the TPS by itself, ie not plugged in, does not generate voltage.

Also, are you using a digital or analog multimeter, the analog ones I prefer because you can see the "sweep" of the tps.

 

The plunger would be left alone to take the "idle" reading, but the car must be "fully warmed" as in idle was 750 rpm before turning the car off or the fast idle cam mechanism removed from the car. When the plunger fully extends the voltage should read about 4 volts or so.

 

Ok I used a DMM and got 1 volt at the harness green and red wire. I had to remove the throttle cable in order to get a reading. Car still has hesitations/detonations but will adjust once more tomorrow.

 

At what rpm's do the hesitations occur? And how does the voltage change as the plunger extends. If using an analog meter you would be able to see if the sweep is a slow and steady one as opposed to jumpy, which would not be good.

 

thanks guys got another tps ad everything was fixed.