ambient temp sensor
- Thread starter zrxkawboy
- Start date
The system is not operational...it always reads 69F regardless of outside temp (so a change in temp at the sensor does not affect the display). I'm just wanting to test the sensor to see if that is the problem. Do they work by a variable resistance, or...?
It's a Thermistor which means thermally sensitive resistor.....GM usually uses Low resistance = High Temp & High resistance = Low Temp.
well than, locating the plug-in at the harness, or pulling it's fuse. ?
Thanks...that confirms what I thought. The sensor seems to be working: it read ~6k at ambient, so I threw it in my garage fridge for a couple minutes, and it read ~15k. I turned the ignition switch on with the sensor unplugged, and the display read 50F. That didn't seems right. Now, even with the sensor plugged in, it reads 50 at all times.
The contacts in the plug look good, but I cleaned them anyway and tweaked them slightly just to insure good contact. Same result: reads 50 at all times. With the sensor unplugged, there is a constant 5V at the connector. Seems logical that this is correct, too.
Any suggestions appreciated on where to go from here.
50F is a default value, I use my Tech 2 to perform a "Instant OAT Update" procedure. Though there could be other ways to force it to update.....Like unhooking the negative battery cable or pulling the HVAC module fuse/s
The signal wire will have a 5vdc bias voltage, The other wire is a Low Reference & should be a good stable Ground.
The signal wire will have a 5vdc bias voltage, The other wire is a Low Reference & should be a good stable Ground.
I certainly agree with you: many times that will wipe the contacts and restore the connection. In this case, though, I had disconnected the sensor and cleaned the contacts, reconnected, then cycled the ignition a few times, and still read a constant 50. The next day, my daughter said it worked fine when she drove it. It seems as though the HVAC module somehow reset itself, as I didn’t disconnect power to it.
Late '00's and early '10's GM vehicles are notorious for fretting corrosion issues in harness connectors.
Clean with electronic contact cleaner and use dielectric grease and issues should be solved.
My old '09 Malibu had a recall for BCM connectors for the same fretting corrosion reasons, brake lights erratic or inoperative it it's case.
Clean with electronic contact cleaner and use dielectric grease and issues should be solved.
My old '09 Malibu had a recall for BCM connectors for the same fretting corrosion reasons, brake lights erratic or inoperative it it's case.
My Subaru Owner's Manual had a note about the OAT display that said it would just display the temp at shutdown until a specific set of criteria were met, IIRC a certain amount of time at a certain speed, to prevent a false reading due to heat-soak from a hot engine or hot pavement or something like that.
I wonder if you could be encountering this type of situation?
I wonder if you could be encountering this type of situation?
