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I came across this forum while searching for an answer to a problem I have been having. I have a silver 06 with the 4.7. My battery light came on the other day on the way to work. I drove it to work and then back and it died as I pulled in the driveway. I assumed it was the alternator as the plastic cover on the wire to the battery had melted off. I replaced it (with rebuilt from advances) and couldn't get the battery to hold a charge so took it in and had it tested. Was told it was bad, so I bought a battery. Put the battery in started it and my battery light came on. I took it back to advanced and they told me the alternator that I just bought was bad. I traded it in for another and put it in. Still not charging the battery. Had it tested and told it was bad. I took it back and had them order a new one. I put it in and still can't get it to charge the battery. I tested the battery and it's good. I have voltage (11 volts) across the two exciter wires in the plug in the back. What else could be wrong? I checked fuses and don't see anything.
 

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Three bad alternators from same store? Looks like it is time to find a new source and then have them test it BEFORE you leave the store. Also, a good charged battery should read more then 11 volts. Even if it reads 12 volts or more with a meter, that does not prove it is good under load. Store should be able to do a load test to verify it is a good battery.
 

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I came across this forum while searching for an answer to a problem I have been having. I have a silver 06 with the 4.7. My battery light came on the other day on the way to work. I drove it to work and then back and it died as I pulled in the driveway. I assumed it was the alternator as the plastic cover on the wire to the battery had melted off. I replaced it (with rebuilt from advances) and couldn't get the battery to hold a charge so took it in and had it tested. Was told it was bad, so I bought a battery. Put the battery in started it and my battery light came on. I took it back to advanced and they told me the alternator that I just bought was bad. I traded it in for another and put it in. Still not charging the battery. Had it tested and told it was bad. I took it back and had them order a new one. I put it in and still can't get it to charge the battery. I tested the battery and it's good. I have voltage (11 volts) across the two exciter wires in the plug in the back. What else could be wrong? I checked fuses and don't see anything.
06commander4.7;

Welcome to the forum;

Your battery should be reading 12 volts - not 11, especially if it's new.

Second; are you receiving any DTC's?
 

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Discussion Starter #4
Thank you guys for the response. Just to clarify the 11V was across the two exciter wires that plug into the back of the alternator. The first two alternators were rebuilt and bought from advanced. The third I actually had ordered new was from O'Rielly's. I am showing a code on the dash (P0622). I looked this up and it has a list of possibilities related to the charging system: Battery Charge, Faulty generator, generator harness open or short circuited, ECM controlled generator, and faulty ECM.

Would I have other symptoms with a faulty ECM? and is there a way to test the ECM
Would I still be getting a voltage across the exciter wires without a ground?

Have I hit my question limit yet?

In my limited experience it still just acts like a bad alternator. If I pull the hot side off the battery it immediately dies.

I appreciate your guys input.
 

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Don't ever disconnect the battery with the engine running!

That can kill a modern alternator.

Make sure that the wiring from the alternator to the battery is good. If it melted the insulating cover on the alternator end, it could have gotten hot enough to have other damage to the insulation on that wire. I would seriously consider replacing that charge wire if possible, but I haven't checked what the battery/charge cables look like on this vehicle and how much that involves.

Have the battery tested again, even if it's new. Have the new replacement alternator tested before leaving the store. If everything tests good, get it all installed and hooked up before starting the car, and don't ever disconnect the battery or the alternator charge wire when the engine is running.

I suspect your original alternator might have been fine initially, and you probably threw away a better alternator than you're going to buy at the stores you're going to.

A battery with a dead cell can overload the alternator and cause the charge wiring to overheat like that, but if the alternator is really strong, it doesn't always damage the alternator.
 

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Discussion Starter #8
Thanks for the responses. I took the alternator to an alternator shop. They tore it apart and found the screw that grounds it to the frame wasn't there. So I thought problem solved. Still not working. I am putting a new pigtail on that fits the plug in the in the back of the alternator as the replacement didn't exactly match factory and I had to break the plastic to get the pins on both male and female ends of the plug to get the pins to slide in. Still have no clue what could be causing the alternator not to charge. The alternator tested good when it left the shop. The battery tested good multiple times and is brand new too. I am getting 11V to the exciter wires in the back. wire from alternator to battery appears good. I'm pretty confused what else could be wrong. Unless the 11V isn't the right voltage. Could the computer be the problem?
 

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Hate to say it but if you have run out of options, might be time to take to dealer and let him hook it up to his machines and trouble shoot it. In the end, it may be something simple but hard to find. My sister cooked the wires on a new alternator because the connection was loose (mechanics fault) which created a hot spot at the loose connection. Shop replaced the alternator and wiring. Simple problem but hard to find until the wires got cooked.
 
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