Coolant temp sensor

JohnBaldwin

the original temp sensor measured less than 100 ohms so I replaced it with a new one that measured 5.5kohms at 0 degrees, 1.8kohms at 27 degrees and 240ohms at 80degrees. I can't seem to get it to accept the calibrations, it is showing the temp at -20degrees. is this a problem with the new sensor?

JHM

Resistance looks correct.
Please follow this diagnostics routine:
https://invent-labs.com/jetronic/docs/en/setup/firststart.html#temperature-sensors

JohnBaldwin

Okay, changed the pull up resistance and now I'm getting it to show the correct temp at idle, however when I move the throttle position it shows a change in coolant temp, the more the throttle changes the lower the temp will indicate. I'm having a problem getting this throttle position sensor to calibrate, almost every time I restart it after a cold soak I will have to recalibrate it. Is it possible a bad throttle position sensor can throw off engine temp readings since they both share the same low reference from the MAP sensor?

JohnBaldwin

jetronic-v1-20260511-122510-v416.imf

10kB

JohnBaldwin

So it only does that while the engine is running and does it even with the tps disconnected. it's a little laggy, but runs okay.

JHM

It looks like a mistake in the sensor wiring.
Describe the changes you made in the wiring.

JohnBaldwin

wire-diagram.pdf

335kB

JohnBaldwin

well I think I found the problem, I was looking at the MAP sensor harness connector instead of the MAP sensor itself, looks like I connected the wires to the MAP and the IAT signals instead of the 5volt and low ref... (facepalm)