Battery light.

[02BlueKJ]

Battery light keeps coming on. It has a newer red top battery. I check the alt output it was 13.5v. Battery went died this morning. Jumped it and drove home fine. Any tips Thanks.

 

[Porkchop]

1st Have you load tested the battery
I know you said it was new but it still could be bad.
Try starting there I would also meter to check for a dain on the battery when turned off
Whats the battery read when running and after you turn it off?

 

[tommudd]

Since its a "new" red top I would of started with the battery, I bet thats the problem since they are pretty much junk anymore. I had two new ones go bad and gave up on them

 

[LibertyTC]

I agree about dead new battery, have a load test for sure, and check for a drain down if it passes load test.
There also is a temperature sensor with pigtail in bottom of tray below the battery, that can cause light also to come on.
I know when dealer installed the battery (just before I got the KJ) on invoice it mentioned a sensor and cost was like $8. Who knows, maybe the wires not connected the best?
Anyways, I have heard from dealer that when you change the battery it is also a good idea to change the sensor.
Page 8F-24 in 04 FSM shows it.

 

[eyehatetofu]

Well here comes a Optima bashing thread. OP you may want to look for answers elsewhere.

Edit: Nevermind. LibertyTC is coming through with some good info.

 

[Billwill]

As stated above there is the battery temperature sensor under the battery that senses the battery temperature so the PCM can adjust the charge rate accordingly. If the sensor fails or is disconnected you will get the light coming on. You need to get the error codes out...this will point to "overtemp" or "undertemp" if the sensor is the issue....if not...the battery light comes on when there is an issue with the alternator not charging correctly...check the charging voltage over the battery and likewise any error codes could point you towards a charging issue.

 

[02BlueKJ]

Had the alternator tested today its ok. The battery temp sensor is 50 bucks at AutoZone and a junk yard has the ecm for 75 bucks. Might try them both i guess.

 

[LibertyTC]

What happened to do a load test first? Is the battery any good?
Only a load test will tell ya the battery story and if it is good or needs replacement.

 

[tjkj2002]

Had the alternator tested today its ok. The battery temp sensor is 50 bucks at AutoZone and a junk yard has the ecm for 75 bucks. Might try them both i guess.

How was the alternator tested?

If a DRBIII('02-'05) or the StarScan('06+) was not used then the alternator was not tested correctly since the voltage regulator is located in the PCM.

 

[02BlueKJ]

What happened to do a load test first? Is the battery any good?
Only a load test will tell ya the battery story and if it is good or needs replacement.

Charged battery and load tested Tested good.

 

[02BlueKJ]

How was the alternator tested?

If a DRBIII('02-'05) or the StarScan('06+) was not used then the alternator was not tested correctly since the voltage regulator is located in the PCM.

The alternator was bench tested at AutoZone. Took out the pcm and found the middle connector was filled with oil. Going to replace pcm.

 

[Billwill]

Had the alternator tested today its ok. The battery temp sensor is 50 bucks at AutoZone and a junk yard has the ecm for 75 bucks. Might try them both i guess.

You can measure the battery temp sensor with an Ohm meter.
Remove it and measure the resistance at room temperature...should be about 2,000 Ohms if I remember correctly. Place it on a light bulb to warm it up....resistance should steadily drop to about 100 Ohms I think.

A replacement ECM would have to be re-programmed at a dealer with various data that exist in your current ECM.
You first need to see if there are any OBDII codes logged to pursue your problem further.....I had a wiring problem regarding the connection of the battery sensor to the ECM.

 

[02BlueKJ]

I picked up a used ecm went to stealship and the tried to reprogram the ecm but it woundnt take the program so theres a 100 bucks down the drain. :flame: My friend think theres a way to rewire the system for a old style voltage regulator is this possible? Thanks

 

[Billwill]

I picked up a used ecm went to stealship and the tried to reprogram the ecm but it woundnt take the program so theres a 100 bucks down the drain. :flame: My friend think theres a way to rewire the system for a old style voltage regulator is this possible? Thanks

You are going about this the wrong way....if you modify the alternator you would have to modify the programming in the ECU to ignore the old system.

First thing to do is get error codes...either from a dealer or do the ignition ON/OFF stunt which works on Kjs up to 2004.
Turn the ignition key ON/OFF rapidly 4 times without starting the engine. After the 4th time leave the ignition ON and the codes should flash on the odometer..oldest codes first and newer codes last. You may need to repeat the procedure a few times to get it to work...sometimes it needs 5 times ON/OFF and it is fussy about the speed you work at.
The codes should point you in the right direction...battery temp. sensor problems are something like P0152/P0153 codes.

I had the battery light on full time on my 2002 CRD and ended up with a wiring problem from the sensor to the ECU.

I can attach the relevant circuit diagrams for the 2002 gasser...which is what I presume you have....and give you some pointers on what to look for in the circuitry but first you need to check your codes to see if it is a temp. sensor or alternator problem.

 

[02BlueKJ]

The ecm is fried it blow a capacitor. The dealer wants 600 bucks for a new ecm. I just dont have that much to fix it. :disgust: