Ambient Temperature Sensor Replacement

Aug 7, 2016
My outside temperature reading in my '98 100 was high by 30-40 degrees on a constant basis. Given that the sensor is 18 years old and this truck lived most of its life in Houston ( I bought it this past summer), its probably not a shock that the sensor aged poorly from lots of significant temperature fluctuation. The sensor is tied into the heating and AC so its not just the dash display that's affected.

The replacement process is very simple. The only slow parts were fiddling out the old sensor from the wiring socket so as not to break the socket and removing the mounting piece that came with the new sensor.

Part # is 88790-22131. I got mine from Amazon. You can order one with the bracket for the LC but you are paying another $30-40 for a bracket you already have.

1) Disconnect sensor with 12mm socket - easier to reach from underneath truck.
2) Access sensor from top - lot more comfortable and the light is better. Press on tab on top of the wire connection end while pulling gently apart. The sensor and socket are held together by this one tab (no side grips).
3) Use a dremel to remove the connection the new sensor comes with (see photo). Someone might be more clever than I was and find a way to disengage the plastic.
4) On original sensor use a small flat screw driver to press upward on the tab connection that holds the metal bracket in. I sprayed with silicon to lubricate and used a bolt placed through the bracket hole to aid in pulling the old sensor off.
5) Sand down the bracket a bit for any loose rust (this just makes it easier to slide sensor back on as well as I don't like rust).
6) Insert bracket back into the new sensor( minding your orientation)
7) Attach sensor back into wiring connection on car
8) Attach bracket back onto frame.
9) Check temperature

The dash reads dead on now and the auto heat settings appear to respond properly.
Photo below of the resistor inside the plastic package - simple device.


Mar 23, 2012
Update: temp reads correctly now.

I don't know why but it does. Maybe I just needed to give the car a minute, instead of swapping it and immediately checking. Who knows....
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