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Battery box sensor?????

L

Loyd

NAXJA Forum User
Location
L.A.(lower arkansas)
Hey everybody! Who can tell me what the little two wire sensor under my battery, built into the battery box, is for? I would guess that its some kind of battery temp sensor, but we all know what guessing gets ya!! Tried searchin' for it but didnt know what to call it so i didnt come up with much.

BTW, 98 4dr sport 4.0
 
winterbeater said:
It's job is to slow down the rate of charge when the battery gets too warm.
Click to expand...

So, a faulty one of those fancy new-fangled sensors could cause the PCM to not signal the alternator to charge?
 
Reading FSM, 5V feeds into the sensor. Resistance decreases as temperature increases. Disconnecting it SHOULD cause infinite resistance and resume normal charging ignoring temperature. Probably triggers a CEL code.
 
Loyd said:
Thanks for the info!! Can it be deleted without causing problems?
Click to expand...

I disconected the one on my XJ which caused a CEL and eventually shut down the engine after 2+ hours on the highway. I was trying influence the rate of charge of the battery in the hot Southern Summer. On a hot summer afternoon the volt meter could remain as low as 13.2 volts while up North in the winter 14.4 volts is not uncommon.
 
From my 98 FSM.

BATTERY TEMPERATURE SENSOR
To perform a complete test of this sensor and its circuitry, refer to the appropriate Powertrain Diagnostic Procedures manual. To test the sensor only, refer to the following:

(1) The sensor is located under the battery and is attached to the battery tray (Fig. 2). A two-wire pigtail harness is attached directly to the sensor. The opposite end of this harness connects the sensor to the engine wiring harness.

(2) Disconnect the two-wire pigtail harness from the engine harness.

(3) Attach ohmmeter leads to the wire terminals of the pigtail harness.

(4) At room temperature of 25° C (75–80° F), an ohmmeter reading of 9,000 (9K) to 11,000 (11K) ohms should be observed.

(5) If reading is above or below the specification, replace the sensor.
 
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