hello im new here i have a 97 neon been running fine. now the battery lights going off n on and it seems to be chargeing right any ideas?

 

If the battery light is on, that means the battery temperature sensor (located on the car front side of the battery box) is either damaged, unplugged, extremely dirty at the connector wires and/or chaffed/broken/cracked wires going into the sensor.

Unless you have a bad regulator in your PCM (extremely unlikely), then your battery is not getting overcharged and therefore, overheated.

Now, you may have an actual problem if your battery is very old, in that it allows the PCM to overcharge and get the battery too hot. Or, you could live somewhere where it gets really really hot, and your battery just does not like that at all.

A new temp sensor (if you need one) is about $20. They are easily cracked, so be careful around them. They are simply a plastic housing for a thermistor held in place with a metal nut which if tightened too much will crack it too.

 

thanks, i checked all my wires and voltages at idle i have 13.5 volts. im guessing the battery temperature sensor is ge off tting hot then cools off letting it charge again. thanks for the help first of the month ill buy a new sensor and let you know if it fixes it.

 

Low charging voltage will also cause that light. 13.5 isnt the greatest. I would unhook the battery with it running and see if it brought the voltage up to 14+ at the terminals. Could be a bad belt, alternator, loose connection, dirty connection.

 

i know its drivein me nuts lol it stays off for a while then comes on if u are runnin down the road u can switch it off n back on real fast the light goes back out. its just weird cause it will come on n off on its own, ill check voltages again tomorrow n see what they are. tryed to check voltage with light on n the darn lite went out before i got outta the seat grrr lol. thanks for the ideas will post what i find later.

 

If the light is on (problem sensed) and you are showing 13.5v, then the PCM and its internal regulator is doing its job properly. When a problem is detected, the PCM reduces the output voltage to prevent the battery from being overcharged and possibly exploding. The car still needs a minimum voltage output provided to keep all electrical systems active while still providing a "trickle charge" to the battery. That's what this sensor is for. If the PCM regulator didn't provide this minimum voltage, then your car might die if you turn on too many systems at once (overload) and/or once the battery drains, your car would just die.

So, if/when your light goes out, and you still have a 13.5v output, then I agree with I_Ride and you need to begin checking your belts, alternator, etc.

Most likely the sensor was damaged and/or the wires/connector has some issues. Fix these, and the problem should disappear and your voltage output should be back into the 14v to 14.5v range.

 

Well im thinkin i found my problem pulled pos battery cable n car shut off. thanks for the help will post more when i can get new alt n install it. gives me time to find oil leak now,lol.

 

I hope the new alt fixes your problem, BUT the advice you got to yank a battery cable off a running vehicle is really wrong. On late model vehicles with computers, yanking a battery cable can send the alternator into a run-away voltage condition where it can put out up to 150 volts. Anything over 18 volts is enough to fry all your electronics; PCM, BCM, TIPM, etc. That "test" was valid 20 years ago. It's no longer an acceptable method. Just a warning to you guys to NEVER use this method unless you like the looks of charred circuit boards.

I see TSBs warning against this regularly.

 

This makes no sense Can you elaborate on how an alternator runs 150volts DC when your cable is off? I have heard of power surges when people drive around with no battery, but not at an idle. Does the voltage regulator turn off or something?

 

What I said makes plenty of sense. I could list 20 references, but how about the link below from AC Delco?

The second you disconnect the battery from the charging circuit, the voltage regulator goes to "FULL FIELD," forcing the alternator to put out max. With the battery in the circuit, Full Fielding an alternator usually only produces 15-16 volts. But with the battery out, alternators are capable of up to 150 volts (low amps but high volts). An 18 volt output is a piece of cake for an alternator in that state. That alone can fry electronics. In fact, car makers now warn that batteries should never be charged with older battery charges because they can put out 18 volts. 16 volts is now the official limit on battery charging.

Disconnecting the battery with the engine running can fry BCMs, PCMs, EBCMs, etc.

Note the multiple warnings on this AC Delco bulletin. Every manufacturer is now issuing this warning.

http://www.onlinetechhelp.com/suppor...AC_english.pdf