On Board Thermometer

How does the on board thermometer work, be mostly accurate and where is the sensor located? Just curious.


My Toyota on-board thermometer is very accurate; I ususally check it against the large wall thermometer at the sports park. The senser is somewhere up front, away from the radiator.

On some cars they are located behind the bumper. That’s why it reads high when you get in it if you park where the sun shines on it (and the parking lot).

Behind the bumper is close enougn,the vehicle(s) I dealt most with about this sensor (S Blazer and full size pickups ,Suburban, tahoe) had them merely clipped to the center support of the core support.

There is some drive time logic progranmed in to deal with heat soak.

Thanks Guys! I’ve been racking (not too hard) my brain trying to figure out where a manufacture would put such a sensor. Having grown up in Arizona, where it can get pretty dang hot in the sun during the summer months, the biggest question was heat soak from sitting in the sun. Curtis

I had one of these on your 87 Dodge Caravan. When new that van had a weak air conditioning. The dealer kept telling me it was fine and the thermometer I was using to measure the temp of the airduct must have been in accurate.

So I added an extension wire to the on-board thermometer (located in front of the radiator) and held that in front of the a/c dashboard airduct. When I showed that temperature reading to the dealer, they accepted it and decided they needed to fix the a/c.

It could be argued the extra length of wire I added to the sensor could have changed the sensor’s resistance. Since the dealer never questioned that, I didn’t bring it up.