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Originally Posted by jdsalas
The manual I have (Chilton) doesn't contain information on how to test repair or replace. I appreciate any info on what to do with battery sensor voltage is to high. THX  |
The battery temp sensor allows the voltage regulator to increase the chargeing rate/voltage for lower temperatures and reduce them for high temps.
The battery temp sensor receives a 5 volt signal from the PCM and is grounded back at another common sensor ground terminal on the PCM so the battery won't and alternator won't have a direct effect on it's operation.
The only things that I know of that would make the voltage high is an open sensor, power side wire off or a disconnected ground wire somewhere near the sensor or high resistance anywhere in that run of the circuit.
I don't have the diagram for the cherokee but the grand cherk diagram shows a red/yel wire as being the power and a blk/blu wire being the ground side (maybe yours is the same?). If the battery temp sensor is the only problem showing up, that tells me that the problem is somewhere between the power terminal at the PCM and the first ground junction after the sensor.
Check the connectors at the sensor and at the PCM. Could have had acid from battery cause corosion on the sensor connector - or something like that.
The ground junction after the sensor should be close to the sensor. Just follow the wire into the harness.
If you check voltages, use a digital voltmeter with 10 megaohms impedence.
With the connector on the sensor, there should be 0 volts on the ground side. The voltage on the power side will vary with temperature but less than 5v.
If the connections are good, the power side at 5v or even slightly above and the ground voltage is 0v then the sensor has failed open and needs replacing, disconnect it and check it with an ohm meter. Infinity (1) on the meter means open - 0 means shorted.
hope this wasn't too involved for what you wanted.....
JD