SmartCraft Air Temp Reading "---"

[MichaelJ3]

Hi All, First time poster, but been following for a while. This is actually my 2nd post, as Savage requested I move this post from the 3.0L section.

I have a 2016 Ranger 1850 LS with 150 Four Stroke, S/N 2B181067, SC1000 System Tach and SC1000 Speedo running SmartCraft V7.0, as well as SC100 Oil Pressure and SC100 Water Temp gauges.

Pulled the boat out of storage this spring, all is awesome, except my Air Temperature reads "---".

• I have pulled the plug on the Air Temp Sensor where it plugs into the Speedo Harness, and replugged it, still reads "---"
• I have pulled the harness plug out of the back of the SC1000 Speedo and replugged it. Confirmed there are no bent pins, still reads "---"
• I entered the Calibration menu on the speedo, turned Off the Air Temp function, and the Air Temp then reads "OFF". Turning it back on results in the "---" reading again.
• I ordered a new Air Temp Sensor, P/N 56-820386A76 since it was only $14.95 to my door, plugged that in last night, Air Temp Still reads "---"
• Air temp was working at the end of last fall, no issues.
• Had the boat out on the water, all the other functions of the gauge package are working perfectly, which would imply that the Motor and Gauges are communicating properly on the CAN network

I have a couple questions:

1. I assume this temp sensor is just a normal thermocouple packaged in a water tight package, and the resistance is calibrated to an air temp. Does anyone know the proper range of resistance across the sensor terminals? I can test it. Could also stick a fixed resistor across the Speedo Side harness and just see if I can get it to read a temp.
2. The air temp sensor plugs into the speedo harness, does it go direct to the speedo, or does it go all the way back to the engine, and then is the air temp get "broadcast" digitally on the CAN network?
3. Does someone have the schematic of the SC1000 Speedo and the Speed Wiring Harness, maybe I can answer my own question.
4. Does anyone have any other suggestions as to what might be wrong? Only Other Thing I can think to do is replace the Speedo?

Boat is a 2016, put into service June 17, 2016, came pre-rigged from Ranger w/ the SC1000 Tach and Speedo, I added the SC100 oil pressure and Engine H2O temp last year -- plug and play.
I would expect that the rigging is still under the factory 3 year warranty for another year.
That said, I'd rather just fix myself if I can, as having the boat at the dealer for a week just to fix this eats into quality boating time, which is at a premium in MN this year.

[EuropeanAM]

Triple-Check under the SPEEDOMETER, Cal-2, External Sensors, and make sure AIR TEMP is set to "Yes" (then SAVE). Complete scrolling through remaining screens until you exit Cal-2 screens.

If this does not resolve the problem, it will be necessary to ohm out the harness and verify that the air temp circuit is intact from the SPEEDO to the Air Temp Sensor.

Hope this is of some help... if not, it would be wise to get it to an Authorized Dealer for inspection.

[MichaelJ3]

Thanks Don, yes, I have several times, turned on and off the Air Temp under external sensors. When it is disabled, the Air Temp displays "OFF" and when enabled, it displays "---"

I can ohm out the connections but need the pinout from the speedo connector to the air temp harness, so I know what I am checking continuity on.
Alternatively, I can just check one wire on the air temp sensor plug, and hit all the pins in the speedo harness, and assume when I find one around zero ohms, that it is connected. Then move to the other pin and check again...but would be better to know which two pins in the speedo harness go to the Air Temp plug.

[EuropeanAM]

Should be able to recognize the colors at the back of the 10-pin plug pretty readily... simply pull the convoluted tubing away from the plug, open the clamshell, and you should be able to see the wire colors readily.

Very similar to this (same basic plug):

How to Disassemble A Smartcraft Cable Connector

[MichaelJ3]

Great idea...I should have thought of that.

BTW, the photos in that post are not visible ... instead replaced w/ some sort of photobucket GIF.

Update: Installed the Chrome Extension mentioned on the Boards forum, solid and can see photos now.

[MichaelJ3]

Hey All, just an update. At Don's suggestion, I checked continuity of the Air Temp Harness. Determined the GND wire was broken in the harness, found the bad spot, cut it out, connected back w/ some watertight shrink tube butt connectors, and all is well again. Thanks for the help!

[EuropeanAM]

Love a simple fix. Good job!