Anyone else have an adjustable battery temp sensor? (tongue in cheek)

:jester:

I didn't realize my '96 even came with a battery temp sensor. I became aware the feature exists when I got my tray from Dirtbound, but since I didn't find a sensor when I changed out the tray I just assumed my Jeep never had one.

Well, while trying to fish some new wiring along the passenger side fender I noticed some wires going into the fender cavity. They seemed to be only loosely there, so I pulled them out, and look at what I found:



Being curious, I gave the rheostat a turn, and it turns nicely. I hope I returned it to something close to its proper position.

Now I'm not quite sure what to do with the situation.

From what I have read the charging system actually does use information from this sensor. Of course mine isn't getting any useful feedback whatsoever with this arrangement. I am thinking I should get a new battery temp sensor and plug it in. If I suddenly have a trouble code I should be able to go back to this bit of creative engineering.

OTOH, having switched to an Optima is there any point at all to trying to use the factory assumptions regarding charging and temperature? Should I just leave this in the fender cavity and forget all about it?

I see the connectors will plug together. Just remove the 'stat and lug the 2 connectors together.

-Ron

Yes I could change the arrangement and delete the rheostat, but I think that would have a very predictable result. I can't imagine someone went to the effort to modify this sensor because everything was working just fine, especially not on this particular vehicle. It seems everything the POs did was the most expedient means of dealing with whatever problem was at hand. I doubt this is any exception.

Anak said:

:jester:


From what I have read the charging system actually does use information from this sensor.

Click to expand...

Quite right that. As the Battery Temperature goes up, the charger rate goes down so as to not cook the battery...

This is what the FSM has to say about the nominal resistance value for the Sensor:

(4) At room temperature, of 25(C) degrees (75(F) to 80(F) degrees), an ohmmeter reading of 9,000 (9K) to 11,000 (11K) ohms should be observed.
(5) If the reading is above or below the specification, replace the sensor.

IMO, the Optima requires greater control and has been designed with OEM charging systems in mind. For what it is worth, I would remove the pot after making sure the Sensor is good. I would most definitely replace it if it were to be proved faulty.

What the PCM does is to reduce the charge voltage from the nice 14.2VDc we see in the snow down to as low as 13VDc in the summer heat. Depending on just how extreme both seasons turn out to be.