MSefi.com read only forum (Jan.15,2018)

Posted some on this in another thread but thought I'd start a new one devoted to it specifically.

I've been working on getting my 455 up and running the MS unit and everything has been going okay except that my IAT sensor ready is way off.

Now about a month ago I had hooked my laptop up to the ECU while connected to the engine. I didn't start it at that time but was mostly just checking that the sensors were functioning properly. At that time the IAT was fine and reading the same as the coolant temp.

Now this past week I've got the engine to the point I could start it and have been trying to tune the warmup enrichments. But one of the first things I noticed is that the IAT sensor was reading really high. On a cold engine, when the CLT sensor was reading 62*F the IAT was reading 297*+. Now just Thursday I checked it again and it was reading -1376*F.

The things I have checked so far:

*Resistance at IAT sensor plug is around 3.9 or so. CLT checks out the exact same on an absolutely cold engine.
*Resistance at the end of the IAT wire run to my relay board is the same as above. Same for the CLT sensor.
*Checked the resistance between PINS 20 and PINS 7 on my relay board cable at the Megasquirt connection end. It came up as 0
*Checked my MS ECU with my stimulator and the IAT functions normally with it.
*Checked the values under the calibrate thermistor portion of Megatune and its values are the exact same as the CLT sensor. Both sensors (IAT and CLT) are GM closed element sensors. Bought from DIY Autotune.

So I'm at a bit of a loss as to where to look next. Should I get another sensor and try it?

Thanks for all of the help!

Well, I think I found the problem. That zero ohm reading is where the problem was at. I double and triple checked my IAT sensor and confirmed it was reading properly.

So, as a last resort I decided to pull the DB37 connector sheilds off both ends of wires. Turns out that one of the wires was pinched pretty badly and was grounding to the connector itself since they are metal.

When I removed the connector, I no longer had a zero ohm reading between PINS 20 and PIN 7. However, when I double checked my CLT sensor wire through this, I found that it had a .41 or so ohm reading between PIN 21 and PIN 19. I don't get any reading from the IAT PIN 20 and PIN 19 so my next test is to see if I even have continutity through the IAT wire itself. Looks like I'll probably have to cut, splice and solder a new wire in.

Thanks,