Battery/Charging System

[yellocoyote]

It's been an interesting day...

Last night on my way home from class, the battery light came on on my dash. Drove all the way home without problem. Once home, I had Aaron check the volts with his scangauge. The gauge showed more volts without the engine running (12.1 volts) than with the engine running (11.4 volts), so we assumed the alternator was the culprit. I stayed home today, and we changed the alternator.

Battery light still came on.

I went to class tonight without a problem. However, on my way home the dash lit up like a christmas tree... all the 'idiot' lights were blinking, the radio shut itself down, headlights dimmed and eventually shut off, windsheld wipers stopped working. With it being dark and rainy, I pulled off and called Aaron for help. Once I shut the engine off, I was unable to get it to start again. Aaron brought the van, and hooked up the jumper cables to the kj's battery, and got it to start... but it wouldn't stay running unless I kept my foot on the accelerator a bit. At that point I decide to make a run for home (5 miles away). Only got a couple miles down the road when all systems in the kj died again.

We removed the battery that was in the kj, and went to have it tested. It tested bad, so we got a replacement for it. Installed the new battery.

Battery light still came on.

So, now I'm stuck. I'm thinking that it would be wise to check the battery cables... but what else should I look for? I've never experienced anything quite like this with prior vehicles before.

 

[kskj]

When I was in moab three of years ago I had to replaced my alternator and the battery at the same time. Both were bad.
Could that switch on the battery tray cause the light to come on ?

 

[yellocoyote]

I did that... all today. Battery light still comes on.

 

[LibertyTC]

After alt change did you have 14.7 volts going out while running? Is it running ok now, just a battery light now? Which alternator did u install?
When dealer replaced my battery they also replaced the battery pad. (I think that is the battery temp sensor pad) That would cause light to stay on if faulty. If you replaced the pad and...
If both the battery is holding a charge and alt is now puttin out... The next to look for is a bad ground or last resort of the charging / regulating circuity..module oh oh.

 

[ShafferNY]

I think my next step would be to test the battery temp sensor, since it controls the charge rate(according to the FSM).

This might explain the battery light illumination. If the sensor has failed, the PCM may not be getting the voltage it needs. It may be 'thinking' the battery temperature is higher than it actually is, thus providing low system voltage and not charging the battery.

 

[JeepJeepster]

No codes? I would think it would throw codes if that sensor was bad but I guess it may not.

Connections all good at the battery? If the alternator and battery are good and its still nto charging then it may be the PCM.. Thats wht regulates the charging of the battery.

 

[Billwill]

You must have codes; the sensor under the battery is a thermo resistor, take it out (with power off) and measure the resistance..should be about 12K Ohms at room temp if I remember correctly. Heat it up slightly (place on a light bulb)..resistance should drop steadily to about 2 K Ohms. Replace sensor. The sensor is there to tell the OBC the temp of the battery..OBC lowers or raises charge current to the alternator field accordingly. Codes are P0514 for out of range, P0512 and P0513 I think for too low/high I believe; this is valid for my 2002 2.5 CRD European spec, the code list in the Sticky is not complete. The Sticky that has the Service Manual for the 2002 Liberty has circuit diagrams for the CRD sensor to OBC, I do not know about your vehicle...I had this problem(battery light on) and could check the wiring from the sensor to the OBC, checks out OK...I need a tool to reset the codes or, I am told, 50 start up and goes will clear the codes...agents are useless. In my case I am driving with the Bat light on...voltmeter shows charging voltage of 13.4V, alternator checked by specialist as was battery.

 

[yellocoyote]

UPDATE:

The old battery that was replaced yesterday appeared to have a crack in it somewhere - evidence of that was seen on the battery itself. Upon further inspection this morning, one of the wires coming off of the fuse box in front of the battery had gotten in contact with the battery acid - it was well over half way 'eaten' by the acid.

There was no other evidence of anything else wrong...

No codes were set at all - only the battery light was illuminated.

The wire in question that had the acid on it was the issue - although I'm still not all that sure what all it controls. Got the wire soldered back together and put multiple layers of liquid tape to coat the bare wires. Everything is secure again, and most importantly... everything is WORKING again! (partysmile) 14.4 volts when running and 12.4 when not running.

 

[ridenby]

Good to hear.

 

[TigerClaws]

Too bad i didnt get your post earlier.. my pontiac grand am 99 did the same thing to me .... christmas early on and alt+batt change in row .... I could have told you that it was a wire that has grounded from acid battery rain lolll damn !! I hated that so much !! You should be fine, that is figuring you've double checked other wires around the battery compartment . Mine was the amplifier sucking all the power to ground it leaving nothing or mostly nothing to the car itself

 

[kb0nly]

So most likely just a battery and that wire would have fixed it.. Oh well you got a new alternator and don't have to worry about nothing now! LOL

 

[yellocoyote]

My thought's exactly! Got a better alternator with a higher capacity too... in anticipation for adding on roof lights next year.

 

[JeepJeepster]

My thought's exactly! Got a better alternator with a higher capacity too... in anticipation for adding on roof lights next year.

From what people say the PCM will not let a higher output alternator put out more than what the stock alternator put out. You would need to get a PCM that was paired with a 160 amp alternator(renny).

 

[yellocoyote]

I guess I'll find out when I do it. For now, I'm happy that everything else is running as it should. If I have issues adding lights, I'll definitely be here asking more questions.