masutin

Hey. I have a NA Miata with -94 engine and wiring harness and MS3 Basic ECU. My variable TPS has never worked well and I noticed that for some reason, previous owner had mixed 5V REF and NB MAIN pins in ECU. I swapped those to right positions and I wished that it would’ve fixed the issue but it didn’t. I’m using 1.8 vtps without idle switch wire and I tried to swap pins in the connector because I wasn’t 100% sure if they were in correct order. I think I might’ve cause a short circuit because ECU turned off and on (my bad, should’ve turn the ignition off before touching those wires) but nothing changed, it was still giving same values in every throttle position.

I checked the green/white wire (tps signal) and there’s no voltage. Is it possible that I blew up a fuse, zener diode or something else?

Also my temperature sensor have never worked with realistic calibrations. I hoped that fixing that ecu wiring would fix that too, but I haven’t tested that yet because I don’t have the head installed right now.

masutin

So apparently there’s no voltage on signal wire when the sensor is not installed (dumbass) but I was using multimeter and found out that there’s contact between 5v ref and ground and I have no sensors installed atm. When I unplug the ecu there’s no contact. Is there a short circuit in ecu or is this normal?

Servaas Schutte

You can test a TPS without it connected by measuring the resistance (ohms) between the 3 wires/pins. TPS is just a potentiometer so you should get a fixed resistance between ground and vref(input) this should not change as the sensor is moved. The other wire will be the signal output and it should change as you move the sensor when you check resistance to either ground or input wires.