QuestionQUESTION: I can not figure out why the battery light will not go off. When it first came on i had it tested and it showed the voltage regulator was bad in the pcm. bought one at a junk yard and had it reprogrammed to my car, charged and tested the battery and battery light was still on. Tested it again and voltage reg still failed. by this time it killed my battery again. now i bought a reman computer from carcomputerexchange.com and replaced my battery. battery light is still on. Had it tested again and the regulator is still failing. Car will still start and i have driven it a few miles over the last couple of days and so far battery hasnt drained but light is still on. Please help! This is the car that my wife and kids use on a daily basis.
ANSWER: Hi Kyle,
When you say you had it "tested and it showed the voltage regulator was bad in the pcm" do you happen to know what the specific fault code number was? If not, why not try a new reading of the problem by turning the ignition key: "on-off-on-off-on and leave on" doing that in 5 seconds or less elapsed time. Then watch the odometer window to notice the mileage reading to be replaced by a 4-digit number preceded by a P. Let me know the number and we'll go from there to resolve this. I have the manual for interpreting what are the possible causes of each such code number. It might be the wiring to the alternator or the alternator itself rather than the pcm "voltage regulator" function. None of the fault codes specifically identify that function as being the cause of a charging problem so you may have received incorrect advice
Please read the PS (below) and respond to it.
Thanks,
Roland
---------- FOLLOW-UP ----------
QUESTION: here are the codes P2503 and P0622
AnswerHi Kyle,
There are basically three possibilities, the alternator is bad, the wiring of its field control wires or its output wire is compromised, or the pcm is bad. Both codes list these possibilities in that same order which suggests to me that the pcm is not the cause unless the other two causes have been tested and eliminated.
Did the person who did the testing actually test the field control circuit's behavior at the plug where it attaches to the generator was or wasn't working? If it was working then the generator is bad. If it was not, then did he check the wiring of that field control circuit for a short or open condition? If the circuit wires were good, then and only then would you conclude it is the pcm itself.
Unfortunately, you need a diagnostic readout box to do the first test of the field control circuits behavior. But if you have an ohm meter or continuity tester you can check the field wires and as well the output wire that goes to the battery.
But based upon my experience I believe that you would do well, partcularly given that you have replaced the pcm, to check the 3 wires, and if those appear to show no damage and as well show continuity and no short circuits to ground, then I would replace the alternator with a rebuilt unit.
Basically the three wires are:
the black/tan wire on pin 1 of the field coil plug should be shown to be connected to ground.
the dark green wire on pin 2 should be connected to pin 19 of the number 2 plug (black exterior/orange interior) of the pcm.
and the fat red wire on the alternator should be shown to be connected to the battery.
If you don't have the ohm-meter, then I would just trace the wires as far as you can along the harness to look for signs of damage, and finding none I would believe that replacing the alternator would solve this problem.
There are several steps to that replacement which I can tell you about, so let me know.
Thank you for your rating and nomination of me. You may do both again if this has proven to be helpful to you.
Roland
