TPS not working

[maidenfan]

G'day, I have a MS1 v3.0 029y4a firmware. Everything works except for the TPS. Tried to calibrate it in tunerstudio, but shows 0 for open & 0 for closed. It used to work before, I had it setup to run 6 cyl in wasted spark with 3 coil drivers mounted to the case, it was all working fine. Car sat for about 5 years, now I converted it to single coil running from Q16, added PWM idle control transistor to case, put everything back together & now tps is not working. I've tried another tps, I'm getting 5V at the grey wire & earth is good, grounded with CLT & IAT sensors at pin 19, did a continuance test form tps signal wire to the DB37 connector at the MS1, all was good. Also re downloading the firmware didn't help. Any ideas?

[DaveEFI]

Obvious next step would be to test with a Stim. If the TPS works on that, it must be a fault with your TPS or wiring. But I assume you don't have one?
Can you get at your MS easily on the car? If so, remove the cover and probe between R9 and ground with your DVM set to volts. With the MS powered up, you should see the voltage change when the throttle is opened.

[maidenfan]

Unfortunately I don't have a stim. Will carry out the test on R9 tomorrow. I did back probe the tps plug between ground & signal wire, had 0V from open to closed throttle, but if I remove the signal wire from the plug & only have the 5v & ground wires connected to the tps I get about 0 to 4.5v from closed to open throttle between ground & signal pin. I will double check that.

[maidenfan]

So does the blue signal wire in the MS loom connect to R9?

[maidenfan]

OK, just tested the voltage on R9. Got 750mV @ closed throttle & 4.29V @ WOT. That indicates wiring ok to the MS right? So what could be up?

[DaveEFI]

OK, just tested the voltage on R9. Got 750mV @ closed throttle & 4.29V @ WOT. That indicates wiring ok to the MS right? So what could be up?

Looks like you have a fault within MS. Does R9 measure at approx 1000 ohms? Is there continuity between it and Pin26 of the processor? And check C9 isn't short circuit.

If all OK, and assuming your firmware is good, it looks like a processor fault.

[maidenfan]

Started tunerstudio with the ms opened up & the tps started working. With the db37 connector plugged straight into the ms with out the end panel & little shield on, the tps works, but if the end panel is on & bolted it stops working, so narrowed it down to the db connector. Solder joint look ok on the connector, can't see anything that stands out.

[maidenfan]

Checked out the db connector on the megasquirt board, all tested out ok. Had the metal hood off the harness a couple of weeks ago, I think when I screwd it back together I may have pinched the tps signal wire between the two halves & now it earths out the wire when I plug it into the megasquirt. Will check it tomorrow.

[maidenfan]

Yep, pinched tps signal wire, all fixed. Thanks Dave.