TPS problem

here is a total WAG...what happens if you manually move the tps like you say to see an output voltage but keep the tps as close to the installed position as possible? Is there any chance of some weird EMF thing going on like from the plug wires or interference like radio interference? That is really weird a tps is just a potentiometer and a very basic device. What about tps wires routed near sparkplug wires?

 

On the bright side at least we know what the problem with TPS load tuning was.

Do you have a scope or access to a scope? I would be wanting to look at the trace from the 5V and output line. I’m thinking you have a either a vibration problem or the mount is forcing the something apart probably the latter……does the signal go away with the TPS in place but not bolted? Does it work if it’s in place but the screws are loose? How about it you hold it tightly in place by hand? Does the TPS sit flat and nice on the mount? Does it slip on easily? This is where I would be looking.

 

If you changed the ecu and the TPS, then the issue must be in the wiring.


One thing to check, with the TPS connected, remove the connector from the ECU and using a ohm meter, check the 3 connections while someone is moving the thottle.

I just checked my wiring diagram for the TEC3 and I see I wrote in a change for the TPS connection. The Gray/Red Strip wire goes to C (+5 volts), the Dk. Blue to B (Thottle Signal) , and the Black/white strip to A (Sensor Gound) terminals. Obviously, something was wrong with the original wire diagram.

Good luck.

 

You probably forgot the cover sheet. Didn't you get the memo?

 

I could only guess that it might be a software problem. I say that assuming that TPS function can be disabled or enabled via a laptop at setup. I don't know if that's actually the case. If it is then I would think it's enabled with the key on and somehow disables for whatever reason when the engine running signal goes back to the ECU.

Is there some new version of the software that is on both of the ECU's?

I know this is far-fetched and then you would have to wonder why they're aren't numerous other complaints of this unless other people aren't noticing it (it goes into some default mode and the cars run okay using other inputs only).

 

Interesting. Maybe the fact that the TPS is providing no expected input (0 volts instead of 1) indicates to the ECU that the TPS is defective. Then the ECU ignores any signals from the TPS or otherwise defeats the TPS input/calculations.

In any event, certainly sounds like you're on the right track.

 

Giovanni,

Any resolution? FYI, I just checked my TPS settings - 0.37v fully closed and 4.94v WOT. Using an early style GM TPS.